# OWB not transfering heat into oil burner



## Mahoney86 (Nov 26, 2018)

I have a newly acquired Central Boiler 1450 outdoor wood boiler. 75' run of 1" thermos pex placed 2 feet underground and then down into my basement Crown oil furnace. My 1800 sq ft home is all on 1 zone baseboard heat (basement is not heated)

I do not have a wood boiler dealer near me so I have been speaking with dealer out of state where I have purchased some products from. I also looked at the install of the dealers furnace and mimicked the same install.

My OWB supply is piped into the oil boiler supply inlet (after the pressure tank and circulator pump). The system returns through a T installed before the oil burner pressure relief valve and back to the wood boiler. The intent here was to keep the oil burner constantly not.

My wood boiler is set at a max temp of 195 with a differential of 10 degrees. I can get to 195 relatively quickly at the wood boiler and I will then open up my valves inside the house for the wood boiler water to circulate into the oil burner.  Oil burner temps are set to 160 high and 140 low. 

I filled the OWB through from the oil burner domestic water side as well as checked all purge valves on the wood boiler side for air. I also ran my baseboards up to pressure and opened up the air bleeder valves one by one to ensure no air in my system. 

My supply from the OWB is hot but I can keep my hands on the pipe for 5 seconds, with a cheap infrared temp meets the pipes are no hotter than 160 even when the OWB is at hi temp mode (200 degrees). The temp gauge on my oil burner reads no higher than 160 as well and the oil burner will still run to maintain that. I’ve even tried turning the oil burner to 140 and the temperature will continue to drop. 

My water condition has a pink dye in it which I can see if I purge any of the drains at my oil burner. Though when I purged my baseboards I only saw clear water. 

Lastly my OWB continues to smolder and then eventually throw a fire out cold because the system is not getting cooled water requiring the OWB to fire. The only way I’ve been keeping a fire for a day is by lowering the fan pulse mode to every 20 minutes for 60 seconds. Then in which the boiler will go into hi temp mode

I have cranked the heat to 70 ( we normally keep the house at 59 during the day and 64 at night due to the oil bills. Have taken long hot showers only to loose hot water ( my oil boiler heats my domestic hot as well.

My dealer suggested maybe since it was a used unit to change the circulator pump. I did that and still cannot seem to get things circulating in my base boards. If I open the purge valve on my OWB supply ( right at the entry into my oil burner ) I get very good water flow and after a few seconds the water starts to steam and I can feel the pex lines really begin to heat up on the supply. My pressure gauge on my oil burner reads 7psi and I have no circulator issues if when I’m hearing with just the oil burner. 

Im really lost at this point. Any thing I should be looking for next?


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## Sodbuster (Nov 26, 2018)

Bump


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## E Yoder (Nov 27, 2018)

Some pictures would help. How does the oil boiler read 7 psi plumbed directly into an open vented outdoor furnace? Something's weird. I would normally separate the pressurized oil boiler from the open outdoor system with a flat plate. But... It should still work, just be harder to get air out, possibly. 
Are the lines coming in from the OWB completely purged of air? If the OWB is lower than the house opening a purge valve/ air bleeder could suck air in.


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## Mahoney86 (Nov 27, 2018)

Here a few quick images. In the last photo I T’ed the OWB lines into a loop bypassing the oil burner so I can keep the circulator running if I am out of town for the weekend etc...

I was also a bit confused how I had 7psi in my oil burner with an open pressure system tied in, I was assuming it was head pressure from my OWB being at ground level and my oil burner being approximately 6-7’ lower than the OWB.

I’m not opposed to a flat plate as I originally had planned on ordering one. Though after speaking with the dealer that we would only be in this home for another 2 or so years ( planning on moving and upgrading house size) it would likely be an unneeded expense at the moment and I would be fine plumbing directly into the oil burner


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## maple1 (Nov 27, 2018)

Tieing an OWB directly to an indoor system like that is something I would most definitely avoid.

Indoor systems are usually designed to operate with a certain system pressure. Take that pressure away and you can get circulators cavitating and air locking and water not getting as high as it needs to. Plus you've introduced a whole pile of fresh oxygen to the whole indoor system which brings corrosion potential with it.

This is almost certainly a trapped air problem. One which would be hard to chase from here, without being there in person.

Just on the 3 pics - are there bleed points in the highest points of those blue & red pipes in the second pic?

Sometimes air can be forced out of piping by hooking up a hose to a low spot in that piping, with DHW pressure on it, and forcing it through & out a high spot.

There could also be a problem with the basic layout of the whole thing. Like, elevation differences all around that would make flowing the water in an open system very hard to do. We don't know much about the whole basic layout. Also hard to get a head around your entire plumbing layout - complete pics and/or a drawing might help. But likely won't substitute for being there.


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## stee6043 (Nov 27, 2018)

Is your outdoor boiler physically higher than all of your basboard units?


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## Mahoney86 (Nov 27, 2018)

The wood boiler is not higher than the baseboard units


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## maple1 (Nov 27, 2018)

I can't see this setup working well at all without a heat exchanger between systems. Even a closed pressurized system can have difficulty if you don't keep enough pressure in it.


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## stee6043 (Nov 27, 2018)

Mahoney86 said:


> The wood boiler is not higher than the baseboard units



I think you're going to have some substantial problems with this setup.  Anytime your circ pump is not running your baseboards will drain if the boiler is below the baseboards.  When the circ pump turns back on you'll get massive air lock.  

I think you're in a no-win situation right now.  Get the flat plate ASAP.


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## TCaldwell (Nov 27, 2018)

This system should work, based on the principle of putting a finger over a straw to hold water as you pull it out of the container, if there are no air leaks, ie can vents higher than the water level in the outdoor boiler, and you have removed the extrol expansion tank for the oil boiler. 
 I do agree the system is probably airbound as purging is more difficult in a unpressurized system, and water quality issues need to be monitored frequently to avoid physical damage to components. 
 The benefits are 1 less circ and no temp loss through a hx.


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## Mahoney86 (Nov 27, 2018)

If I go with a flat plate, what size is recommended? I see a bunch I can get on Amazon Prime.

Also I would like to do as little modification to my current piping, any recommendations on the install layout of the flat plate? Can I plumb the oil burner side to the flat plate exactly as I have it now and then just plumb the OWB supply and return to the flat plate. Would I need any additional pumps?

With the flat plate how do I heat my internal domestic hot water? I thought this was the whole reason of having the OWB flow through the oil burner


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## warno (Nov 27, 2018)

To run a FPHX you would simply tie your oil boiler into one side of it and the wood boiler into the other. Make sure you have an opposing flow between the 2 sides. You could very easily install one based on your pictures. You could then pressurize the oil boiler side and leave the wood boiler side as an open system and I think you'll be pretty happy.


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## E Yoder (Nov 28, 2018)

A couple additional thoughts-

Hot from the OWB should be entering at the relief valve tee to send the hottest water out to the baseboards. Blue should be to the lower tee on the return. Right now water temps are mixing in the boiler. 
As was mentioned the baseboards will not drain provided no air vents are open, they just run in a slight vacuum. 
In the pics the ball valves are all closed, I'm assuming the two at the boiler tees would normally be open, the crossover stays closed? Sounds obvious, but I've seen about everything. 
The same tees could be used with a flat plate, but you should pump out of the drain, returning hot into the top. Counterflowing through the flat plate.


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## maple1 (Nov 28, 2018)

Don't think those high spots in the red & blue, between the basement wall & the oil boiler, were addressed.

If you really want to make this work at all no matter what route you take, you really need a spot in those two high spots to get the air to bleed out of. So I would start there. Cut in bleed valves. That might be all it would take to get the existing setup to get some heat going. The setup still might be problematic, but the cost of doing that little bit will be cheap & easy & will be needed regardless.


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## Mahoney86 (Nov 28, 2018)

Will I still be heating my domestic water when I have the plate exchanger on?

In regards to the high point on the pex lines, figured that may be part of the issue. If I’m going to cut the lines to add another T and a drain valve, I could really just do some slight rerouting and keep the lines down low by running them horizontally . I only ran them up hi to have a little cleaner look in the boiler room


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## E Yoder (Nov 29, 2018)

You said the oil boiler heats your domestic water, correct? Then if you heat the oil boiler it should heat the domestic water. 
The high points may be air locked as was mentioned. Teeing in domestic water pressure with a ball valve would allow you to purge supply and return in seconds. Then the high point should be fine.


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## Mahoney86 (Nov 29, 2018)

E Yoder said:


> You said the oil boiler heats your domestic water, correct? Then if you heat the oil boiler it should heat the domestic water.
> The high points may be air locked as was mentioned. Teeing in domestic water pressure with a ball valve would allow you to purge supply and return in seconds. Then the high point should be fine.



Yes oil burner heats my domestic water.

See i have purged the supply and return lines of the OWB with domestic water a few times now so I would be amazed if I have any air locks at those high points ( I guess anything is possible though)


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## Mahoney86 (Dec 1, 2018)

Ok, I ordered a flat plate heat exchanger last night and it will be here today (good ole Amazon Prime!) Last night I got into the crawl space and removed that High spot on the supply and return to the wood boiler now I have a straight horizontal run and then down into my oil burner.

I fired up the wood boiler just to see if it would circulate water. In bypass mode I read 163 on both the supply and the return while in bypass. I turned down the high and lows on the oil burner and opened up the valves from the OWB. Eventually the OWB went into hi temp mode, the oil burner never went above 160 despite the temperature of the OWB lines being in the the mid 180s per my cheap infrared thermometer. All of the cast iron pipe into the boiler was 185-190. The OWB return line was at 130* and all of my baseboard pipes would not read anything more than 80* with just the OWB. I was hopefull it would maybe settle in as the temp gauge on the oil burner eventually got to about 170 after  a few hours of the OWB going. I woke up at 530am this morning to the oil burner running (hi and low temps were set to 140) and a Fire Out code on my OWB.

So needless to say removing the high points and rebleeding my lines didn't help. Its definitely not worth the headache trying to make this work so I am happy I have the flat plate HX coming today.

Can someone guide me on how to install the HX? I know once side gets the wood boiler return and the wood boiler supply, though how do I plumb the oil burner side? Am I just taking the blue return pex line coming out the back of my oil burner into one side and then the red supply at the bottom of the oil burner into the opposite side of the plate exchanger? Looking at some videos online it looks like many people are just putting the plate exchanger inline of the oil/propone boiler supply and not even touching the return.


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## warno (Dec 1, 2018)

To plumb in your flat plate HX it requires counter flow internally.  So just think about it as both your "cold" lines go on one side and both your "hot" lines go on the other. 

"Cold" lines being your OWB return and oil boiler supply to HX. 

"Hot" lines being your OWB supply and your return to oil boiler. 






You will need a circ on both sides to push water through both sides. And try your best to keep the HX as vertical as possible. 

To the others replying here please correct me if any of this is wrong.


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## Mahoney86 (Dec 1, 2018)

I would like to leave as much as my plumbing in place as it is, unless of course I need to modify it.

But will a setup as shown in the attached mark up work? Sorry it is a crude sketch


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## maple1 (Dec 1, 2018)

So it sounds like OWB flow isn't making a loop into the house & back again - at all? Or am I misunderstanding something? Did you follow the heat from the OWB & see where it goes?

Just from that, it sounds like there are other issues of some kind going on that should be sorted before you try adding a HX. If the OWB water isn't at least making a loop into the house & back again, that's 3 strikes all at once.


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## Mahoney86 (Dec 1, 2018)

The heated from the OWB will make a loop when I have that bypass valve open and no water going to the oil burner.

It does not appear to be making a loop when I send water through the oil burner


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## maple1 (Dec 1, 2018)

Was the oil boiler circ running when you tried that? Did you try it with it both off & on?

A couple better pics might help. Still not sure how things are flowing here.

Which way does that oil circ flow when it is running? Down or up?


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## Mahoney86 (Dec 1, 2018)

Yes circ was both running and not running. Cranked the heat up to 68.

I will get some pictures tonight. The oil circus flows down to where my pex tie in is and then elbows back into the boiler. 

If i open any of my purge valves water definitely flows out well.


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## maple1 (Dec 1, 2018)

If you get a free flow into the house and back again thru that short line that bypasses the oil boiler, then close that ball valve and open the other two, I am failing to see why it wouldn't work it's way through the oil side. With all that's posted.


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## maple1 (Dec 1, 2018)

Is the oil side working right on it's own? Heating the house ok?


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## Mahoney86 (Dec 1, 2018)

As am I. My water conditioner has a purple dye to it. If I open the OWB purge, I get a steady stream of purple. If I open the OWB supply I get purple. If I open the pressure relief valve on the backside of the boiler where my OWB return is, I get purple water.

I just think for some reason or some how I am not getting that water to push into my base boards. I can only think it is a pressure or air issue.


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## maple1 (Dec 1, 2018)

So it is going thru the boiler then?


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## Mahoney86 (Dec 1, 2018)

maple1 said:


> So it is going thru the boiler then?


Oil side works perfectly on its own.

It would appear it’s going through the boiler but it doesn’t make its way up into the baseboards and get circulated


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## maple1 (Dec 1, 2018)

Are you sure those are 1" lines? Could be the pics but they look smaller.


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## Mahoney86 (Dec 1, 2018)

1” lines from boiler all the way to house. I downsized to 3/4” lines in the house transitioning to the 3/4”’lines on the boiler.  I could not find 1” lines locally


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## maple1 (Dec 1, 2018)

What do you have for a circ on the wood boiler?


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## Mahoney86 (Dec 1, 2018)

A new taco 007-F5


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## maple1 (Dec 1, 2018)

That's not a very high head circ. Could be the most of the problem. Just not moving very much water.


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## Mahoney86 (Dec 1, 2018)

Possibly, shame I literally just bought it because I thought maybe the old one was bad.

Any thoughts on the connections to the Flat plate? I’ll try that tomorrow and if still nothing I’ll upgrade to a different circ pump


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## maple1 (Dec 1, 2018)

I would get a bigger circ in place before I swapped the HX in. If you aren't moving enough wood water now, the HX won't improve things. It will actually add head. If you get a proper sized circ, it might do OK without the HX. Since you said the oil side seems to be working fine.


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## Mahoney86 (Dec 1, 2018)

I’m no expert but I would be really surprised if I’m not moving enough water, I guess anything is possible. 

When I open the valves the water comes out with some good force.

The heat exchanger was delivered this afternoon so i think I’m definitely going to use it regardless


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## maple1 (Dec 1, 2018)

I'm away from my computer so can't get everything in front of me at once. But - you have 75', one way, of 1 inch pex. Correct? And how much 3/4"?


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## Mahoney86 (Dec 1, 2018)

75’ of 1”’and 14 feet or so 3/4”


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## warno (Dec 1, 2018)

I have to agree on the circ sizing. I got to thinking the same thing about all the components you were saying you had on the loop. Like maple said if you can't move the water you'll have problems.

@Mahoney86 I don't think your drawing on the HX plumbing was right. You need to make sure the hot side from OWB boiler and the hot side to oil boiler are on the same end. You want an opposing flow through the HX.


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## maple1 (Dec 1, 2018)

One way? I did some quick looking and from what I saw the absolute most you'd flow is maybe 5gpm. That is not taking into account whatever fittings you also are going thru or whatever else might be adding head, just assuming straight pex. One elbow adds about 10' of pipe length. That's a killer on the 3/4.


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## Mahoney86 (Dec 1, 2018)

maple1 said:


> One way? I did some quick looking and from what I saw the absolute most you'd flow is maybe 5gpm. That is not taking into account whatever fittings you also are going thru or whatever else might be adding head, just assuming straight pex. One elbow adds about 10' of pipe length. That's a killer on the 3/4.


Yup, one way. Each line has 4 elbows as well so eeek. My local hardware store has 1” pex in White but only 5’ sections. I guess i could tear all this stuff out and stick with 1” to the heat exchanger


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## maple1 (Dec 1, 2018)

You could use 1" copper too, right over to where the 1" pex comes thru the wall. A bit spendy but...

Also, not sure, but internal flow thru the inside boiler could have a short circuit between the bottom fitting and the relief tapping. Just a guess. Could be the shortest path so minimal chance for mixing. I would definitely first work on getting my wood boiler loop flow where it should be though.


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## Mahoney86 (Dec 2, 2018)

I don’t know if this helps anything but I just did some temperature readings with my cheapo infrared thermometer. My OWB has not ran in over 36 hours and it’s 60 degrees today so no boilers are running. 

Bottom pipe on oil burner is 147.2
OWB supply pipe at oil burner is 140.5
Return line pex back to OWB is 139
Analog Temp gauge on oil burner says 140

The temperature on the wood boiler controller reads 148
The supply pex at OWB is 139.8
The return pex at OWB is 137

With the elevation difference of where my OWB sits compared to the basement location of my oil burner I am getting a psi reading of 5psi on my oil burner


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## stee6043 (Dec 3, 2018)

Silly question - when you're trying to run the OWB without the boil boiler does the return piping on the oil boiler get warm at all?  Have you tried running the oil boiler circ at the same time you're running the OWB?  Is it possible you've got a check valve at the oil boiler messing with your flow?


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## Mahoney86 (Dec 3, 2018)

stee6043 said:


> Silly question - when you're trying to run the OWB without the boil boiler does the return piping on the oil boiler get warm at all?  Have you tried running the oil boiler circ at the same time you're running the OWB?  Is it possible you've got a check valve at the oil boiler messing with your flow?



The return piping to the OWB does get warm but the return piping on the oil burner does not. I make sure the oil burner circulator is running when the OWB is circulating as well.

Anything at this point could be possible but I do not see a check valve anywhere.


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## stee6043 (Dec 3, 2018)

Mahoney86 said:


> The return piping to the OWB does get warm but the return piping on the oil burner does not. I make sure the oil burner circulator is running when the OWB is circulating as well.
> 
> Anything at this point could be possible but I do not see a check valve anywhere.



A question about your piping - you tied your return (blue) into what appears to be your pressure relief plumbing on the oil boiler.  Is there a connection coming from the house return that isn't shown on that same pipe?  I assume there is but it's not pictured.  Also - is that a bypass of some sort coming off the supply side of the oil boiler?  This is the smaller diameter copper not far from your OWB additions.  Does that line have a shutoff?

Assuming your return is pulling from a house return line is there something in your plumbing that prevents the OWB circ from sending supply straight through the oil boiler, straight to the blue return line without going through the house?


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## Mahoney86 (Dec 3, 2018)

You're correct the OWB return piping is plumbed into the oil boilers pressure relief. I wasn't very sure about this connection but 1 installer and 1 dealer said this would work. There is no other piping coming in or out of that relief valve except the OWB piping.

That smaller diameter copper pipe at the bottom of the oil burner is actually the domestic water feed line to fill/pressurize the system. This is how I back flowed domestic water to my OWB to fill it. This does have a shut off and is currently off.

I don't see anything preventing the OWB from going directing into the oil burner like it is. The only thing I can think of is that the oil burner pressure relief valve is maybe not connected to the oil burner supply/return somehow. I do get hot OWB water from that relief valve if it is opened so Im at a loss.


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## stee6043 (Dec 3, 2018)

Mahoney86 said:


> You're correct the OWB return piping is plumbed into the oil boilers pressure relief. I wasn't very sure about this connection but 1 installer and 1 dealer said this would work. There is no other piping coming in or out of that relief valve except the OWB piping.
> 
> That smaller diameter copper pipe at the bottom of the oil burner is actually the domestic water feed line to fill/pressurize the system. This is how I back flowed domestic water to my OWB to fill it. This does have a shut off and is currently off.
> 
> I don't see anything preventing the OWB from going directing into the oil burner like it is. The only thing I can think of is that the oil burner pressure relief valve is maybe not connected to the oil burner supply/return somehow. I do get hot OWB water from that relief valve if it is opened so Im at a loss.



My two cents - you're narrowing in on root cause here.  I still think you should use the flat plate HX, for the record, but I'd bet right now that you've also got a plumbing issue.  Is there any reason you can't tie directly into the system return vs using that pressure relief circuit?  Depending on the internal plumbing of your oil boiler that pressure circuit could be absolutely worthless.  It may well be preventing any flow from your house.  It's also not likely sized correctly (internally) to support the flow rates you need.

Don't buy a new pump.  Relocate that return line.  And install the HX for long term reliability.


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## stee6043 (Dec 3, 2018)

stee6043 said:


> My two cents - you're narrowing in on root cause here.  I still think you should use the flat plate HX, for the record, but I'd bet right now that you've also got a plumbing issue.  Is there any reason you can't tie directly into the system return vs using that pressure relief circuit?  Depending on the internal plumbing of your oil boiler that pressure circuit could be absolutely worthless.  It may well be preventing any flow from your house.  It's also not likely sized correctly (internally) to support the flow rates you need.
> 
> Don't buy a new pump.  Relocate that return line.  And install the HX for long term reliability.



Worth clarifying - once you install the flat plate HX you'll use the pump from the OWB to constantly circulate through the HX and back to your OWB.  The oil boiler circulator will move the water through the house.  By installing the flat plate HX you would essentially eliminate the need to relocate that return line.  You'll relocate it to the flat plate HX, along with the supply, and all the other plumbing modifications you made become obsolete (for the better).


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## Mahoney86 (Dec 3, 2018)

Here is a little more overall picture of the front of my oil boiler 

So i think I’m going to scrap all of the 3/4” pipe. I’ll be out of town this weekend at my hunting cabin where I know I can get longer lengths of 1” pex. So I’ll change that piping from the OWB and plug 1” into the HX.

As far as the oil boiler side of the HX goes it sounds like I can get rid of the blue return line off the back of the oil boiler. Would I just be adding another T at the base of my boiler where I have the red supply pex? And just create a loop into the HX and back into a newly added T? 

One of the biggest things I need to be able to do is very easily shut off the supply to the HX on the oil boiler side as I travel a lot for work and am in the mountains many weekends through winter. I want to be able to put the OWB in a by pass recirc mode easily and keep the oil boiler separate as to not waste oil heating the OWB while I’m not here


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## Mahoney86 (Dec 4, 2018)

Would something like this work? After I drew the sketch and looked at it more I am thinking it would not work because I am adding a line to the HX before the recirculating pump and likely will cause cavitation issues? Can I make all my connections to the HX at the bottom Tee of the Oil Boiler?


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## stee6043 (Dec 4, 2018)

Mahoney86 said:


> Would something like this work? After I drew the sketch and looked at it more I am thinking it would not work because I am adding a line to the HX before the recirculating pump and likely will cause cavitation issues? Can I make all my connections to the HX at the bottom Tee of the Oil Boiler?



That won't work.  You can tee into the return line where you have it marked but you need to come back into that line (from the HX) upstream of the existing circ pump.  The way you have it drawn now is eliminating the pump from the circuit which will not work.  You want your existing oil boiler circ pump to pull supply from the house, send it through the HX, and then send it back through the oil boiler the way it currently does it.  This way your oil boiler can effectively work as a backup. And your plumbing is sure to work.

The bypass you have drawn will work if you need to run the OWB pump while away for work.  Make sure you're using full port ball valves for those shutoffs.


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## stee6043 (Dec 4, 2018)

The problem you're struggling with is that you will need to cut some pipe.  Not ideal for the average DIYer (at least not me).   You can get black pipe cut and threaded and Home Depot and Lowes.  Probably Menards too.  I'd recommend you modify that piece of pipe between the ball valve and your existing pump.  Add two tee's with another ball valve between them and you're set.

Your existing ball valves are perfectly placed to enable this work.  You can make this modification without draining the whole system.  You will, however, end up with air in there after you're done.


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## Mahoney86 (Dec 4, 2018)

I actually do not think that will be terrible to do. I have ample amount of copper above that valve and circ pump. I cannot braze for the life of me, but I can install sharkbite fittings and install copper pipe with (2) Ts on it before that circ pump. I don't think I would modify the pipe after the valve as its 1 1/4" black iron, the copper above would be fairly easy to do.


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## stee6043 (Dec 5, 2018)

Mahoney86 said:


> I actually do not think that will be terrible to do. I have ample amount of copper above that valve and circ pump. I cannot braze for the life of me, but I can install sharkbite fittings and install copper pipe with (2) Ts on it before that circ pump. I don't think I would modify the pipe after the valve as its 1 1/4" black iron, the copper above would be fairly easy to do.



Let us know how it goes!    Make sure you put a shutoff between those two tee's.  You'll need to have a way to force the flow into the HX once installed.

And if you do end up needing to do some work on the black pipe it's really not that bad.  But you'll need two pipe wrenches and some pipe dope.  Lowes/HD can cut and thread to size.  But yeah....shark bites are slick, though not cheap.


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## Mahoney86 (Dec 20, 2018)

Finally getting around to putting the HX on and before I go cutting up copper, I have a thought that I’m not sure this is all going to work as planned.

In my original posts I mentioned the oil burner also heats my DHW. If I plumb the HX into my return side of my oil burner ( before the circulating pump) won’t my oil burner get cold and ultimately loose hot water temp enough that my oil burner will fire? This creates another problem for me as I will have my hi/lo on the oil burner set low so I don’t see myself having any nice long hot showers. 

Please tell me I’m wrong or if I should rethink my plumbing connections prior to hooking the HX up


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## stee6043 (Dec 20, 2018)

Mahoney86 said:


> Finally getting around to putting the HX on and before I go cutting up copper, I have a thought that I’m not sure this is all going to work as planned.
> 
> In my original posts I mentioned the oil burner also heats my DHW. If I plumb the HX into my return side of my oil burner ( before the circulating pump) won’t my oil burner get cold and ultimately loose hot water temp enough that my oil burner will fire? This creates another problem for me as I will have my hi/lo on the oil burner set low so I don’t see myself having any nice long hot showers.
> 
> Please tell me I’m wrong or if I should rethink my plumbing connections prior to hooking the HX up



You're wrong .

The circ pump on your boiler is pulling return water from your home and pushing it back into the boiler, correct?  It should be.  If it's plumbed correctly once you add the HX to the return side your circ is going to pull return water from your home, send it through the new HX (which will heat the water above the set point for the boiler) and then send it thru the oil boiler and back to the rest of the house.  The flat plate will heat the water, the oil boiler will not need to fire unless your wood burner burns out.


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## Mahoney86 (Dec 20, 2018)

Correct the circulating pump is pulling return water from my baseboard system. One my house thermostat calls for heat the circulating pump kicks on.

However my DHW supply is all seperate connections and is fed from my well pump. 

I guess I am struggling to understand how the oil boiler will stay hot unless I am actively circulating how water from my OWB through the oil burner and into my base board system


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## maple1 (Dec 20, 2018)

Mahoney86 said:


> Correct the circulating pump is pulling return water from my baseboard system. One my house thermostat calls for heat the circulating pump kicks on.
> 
> However my DHW supply is all seperate connections and is fed from my well pump.
> 
> I guess I am struggling to understand how the oil boiler will stay hot unless I am actively circulating how water from my OWB through the oil burner and into my base board system



Well, the assumption is that your house will be needing heat quite often. During which times the HX should heat your oil boiler well above the oil burner setpoint.

If everything sits there for long periods not doing anything to heat the house, then yes your oil boiler would cool off and cut in. The same way it would right now before you make any changes.


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## mustash29 (Dec 21, 2018)

You will need to plumb it as follows.

Loop 1 - Wood boiler to HX.
Loop 2 - Other side of HX to oil boiler jacket.  Both of these pumps need to run 24/7.
Loop 3 - Normal oil boiler, air separator, expansion tank, zone valves, pump, house heating loads, etc.

With this setup you run the wood pump when you have a wood fire.  Heat is transferred through the HX and the 2nd loop keeps the oil boiler jacket (and your internal DHW coil) in hot standby.  When a zone calls for heat the oil boiler distributes it like normal.  If anything goes wrong (no wood fire, pump 1 or 2 fails, etc.) then the oil kicks on in backup.


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## Roundgunner (Dec 21, 2018)

I have a double set up (2 houses and now an apartment) just like Mustash 29 describes above in service for 5 years now. I also use the return water from the big house to heat the new 1200 SF apartment above the garage. It is a complicated diagram but it may help.


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## Roundgunner (Dec 21, 2018)

I do have a lot of flow, lots of pumps.


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## Roundgunner (Dec 21, 2018)

The manafolds. It is a big house and it gets plenty cold here.


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## Mahoney86 (Dec 24, 2018)

I am going to have to figure out the additional pump to keep the oil boiler water jacket warm as the oil boiler definitely kicks on whenever the demand for hot DW is needed.

Before I do that I still need to figure out much more on the wood boiler side. 

1) very hard to keep adequate coal bed as I can get the water temp up to 195 in under an hour. This in turn leads to the fire going out each night for the last 3 nights, but wake up to a full load of wood in the boiler. I’m splitting my normal size wood even smaller to try and get it to burn down to coals quick. I’m burninb locust right now that’s 18% moisture after a fresh split. 

2) wood boiler keeps going into Hi Temp mode (200+ degrees) which is one of the major reasons I also can’t develop a coal bed. The wood boiler stops all functions until the temperature drops. 

3) despite the hi temp going off, my cheapo laser thermometer only reads 178 degree on the OWB supply line pex right at the heat exchanger. Return line temp reads 176.

Right now my OWB is set for a high temp of 195 and low of 185 with a differential of 10. I also have it set for every 20 minutes to give a 60 second pulse of air which likely doesn’t happen since I’m in and out of hi temp mode. 

I figured yesterday would be a struggle as the temperature outside was up in the mid 40s but was very surprised to wake up this morning to fire being out, the wood I put in last night barely chared and the fire being completely out. Sounds like the oil burner likely ran all night. It was down in the low 30s last night


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## maple1 (Dec 24, 2018)

If you aren't moving the heatout of it, that will all happen.

So sounds like you should get that part figured out, and the wood boiler is doing ok. Or ok enough to demand the moving heat out issue is current issue 1.


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## Mahoney86 (Dec 24, 2018)

Any ideas as to why the heat isn’t moving out? I’ve pushed domestic water via a garden house through the OWB lines from the heat exchanger out. 

My house is getting heated as the oil boiler didn’t run at all during the day yesterday and I brought the house up to 70. All the lines are now 1” pex.


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## stee6043 (Dec 24, 2018)

Did you install the flat plate yet?  Your plumbing (using the overpressure for return) is the reason you're not moving heat.  I thought that part of the mystery was solved


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## maple1 (Dec 24, 2018)

You should update as to what changes have been made since the first posts and pics.


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## maple1 (Dec 24, 2018)

Mahoney86 said:


> Any ideas as to why the heat isn’t moving out? I’ve pushed domestic water via a garden house through the OWB lines from the heat exchanger out.
> 
> My house is getting heated as the oil boiler didn’t run at all during the day yesterday and I brought the house up to 70. All the lines are now 1” pex.



Some conflicting info posted. Here saying oil not cutting in at all during day, prior post saying definitely cuts in for DHW.


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## Mahoney86 (Dec 24, 2018)

To clarify I did not hear the oil boiler run at all yesterday until my wife took a shower and there was a demand for domestic hot water. Other then that I did not hear the oil boiler run until I woke up this morning to the OWB fire out.

Attached is my latest changes to the system. I installed (2) Tees and a ball valve on my base board/oil boiler return line. Right now the Ball valve is closed forcing water to go directly into the bottom of the heat exchanger. It then comes out the top of the heat exchanger and goes right into the oil boiler circulator pump. 

The OWB boiler lines have all been upgraded to 1” pex going directly into the heat exchanger. The OWB supply goes into the top and the return into the bottom. I installed purge valves on each line and also also Teed the 2 lines together with a ball valve to bypass the heat exchanger if needed. Disregard the old 3/4” pex as I haven’t tore it all down yet


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## warno (Dec 24, 2018)

What are the dimensions of your plate heat exchanger? Plate count and HxWxL measurements? 

Do you know how many GPM your OWB side is running? And how many GPM your oil boiler is running? 

If you are only getting a delta T of 2° through your FPHX you definitely have a flow issue. Even though your HX looks small you should see more than 2°.


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## Mahoney86 (Dec 24, 2018)

Heat exchanger is 5x12 and 20 plates with 1 1/4” fittings. It’s supposed to be rated for 330,000BTU

Not sure about the flow on either but I do know I have a much larger pump on my oil burner


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## warno (Dec 24, 2018)

Is there anyway you can check the flow on OWB side? Possibly unhooking the return line and running into a bucket while timing it.  

Pump size dimensionally doesn't mean a whole lot.  I'm wondering if you possibly have an air lock somewhere on the OWB side. Mine just had that problem the other day. I had really low delta Ts and the pump was making alot of noise because it was stuck in an air bubble. If you have an air pocket somewhere that holds up flow you will have this problem.

How did you go about purging the wood boiler side?  Also I can't remember for sure the rules about the FPHX but I thought they were supposed to stand up if at all possible.


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## Mahoney86 (Dec 26, 2018)

Little day after Christmas update. So Christmas Eve I turned my oil burner hi down to 145 and low of 140, I figured let me turn this thing down as low as it can go. I also turned my OWB to a hi temp of 190 with a 10 degree differential. It is also supply a 60 second puff of air every 10 minutes to keep the coals going. 

So I woke up Christmas morning to a warm house (68*) and to my amazement when I looked outside heat was coming from the OWB chimney. I went outside to check and a beautiful bed of glowing coals and all the wood had burned down. So far this has been the case each morning where today I almost lost the coal bed with how well it burned down!

There are still a few issues I can’t seem to figure out. With lowering the OWB hi temp, I have solved the issues of the OWB going into Hi Temp mode, but the water coming into my heat exchanger is now even colder (168-172 degrees as compared to 178-180 when I had the OWB set to 195 degrees). I still find it hard to believe with thermopex buried 2’ underground that I’m loosing 20+ degrees temp on only a 75’ run when outside air temps are in the low 40s. 

This brings to my next issue that the 168-172 OWB supply lines are only keeping my oil burner lines around 150-156 degrees, hence the reason why I now have my oil burner set points so low. Otherwise the oil burner drops below the 145 set point. I do have 10’ of OWB supply and return lines ( in my badement) that are not insulted which could certainly be part of the problem but would I really lose 20* or temp?


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## maple1 (Dec 26, 2018)

That's not an overly big hx, a bigger one would help.

Can you post temp readings (accurate ones) at all the ins and outs of the HX. Both with and without the oil side flowing. Still sounds like you are not flowing enough through the wood loop.


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## warno (Dec 26, 2018)

I could not agree more with what maple1 is saying. It still seems you aren't flowing enough gpm on the wood side. 

The exposed lines can't hardly be the issue my entire garage loop is not insulated and it goes through 2 small WAHXs and over 40 feet of 1" pex and I'm barely getting a delta of 20 through that loop. 

Also are you sure you have opposing flow through the FPHX? Hot wood boiler supply entering the same side as return to oil boiler. 

When I ditched my 20 plate HX and went with a 90 plate to charge my storage everything changed for the better. I also redid my plumbing to reduce head loss but the bigger HX was a huge improvement. Like I said though even with your 20 plate you should be seeing better results.


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## Mahoney86 (Dec 26, 2018)

Here are the most recent numbers

System Off:
OWB Supply :173
OWB Return : 173

Oil Boiler in to HX : 142
Oil Boiler out of HX : 150

System On

OWB Supply : 174
OWB Return : 125

Oil Boiler in to HX : 147
Oil Boiler out of HX : 161

As far as the plumbing to the HX goes the cold water return from my baseboards goes in the bottom of the HX. The Return to my OWB goes into the bottom as well. OWB Supply goes into the top of the HX and the water sent back into the Oil boiler goes out the top


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## maple1 (Dec 26, 2018)

Looks like a flow imbalance there. Too slow on wood side. Either some air remaining, or circ too small. Suspect circ undersized. I would also likely use a much bigger HX.


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## warno (Dec 26, 2018)

Definitely a lack of flow on the wood side. What circ are you running on the wood side?


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## maple1 (Dec 26, 2018)

Post 33 said Taco 007F5. Not sure if that has been changed. Getting rid of the small pipe would have reduced head but adding the FPHX would have added.


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## maple1 (Dec 26, 2018)

Also, I dont think that HX mounting position is recommended, as also mentioned, but not sure how it would affect things.


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## warno (Dec 26, 2018)

maple1 said:


> Also, I dont think that HX mounting position is recommended, as also mentioned, but not sure how it would affect things.



Everything I've read you want your plates as vertical as possible if at all possible. With supply and returns top and bottom. I'm wondering if there's possibly air trapped in the plates on the boiler side and it's losing efficiency. I know the spaces between ther plates isn't much but it doesn't take much air to screw with things.


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## warno (Dec 26, 2018)

I'm going to say you need to start questioning your circ on the boiler side. In your posting you said there's 75 feet of 1" pex. In my quick reread I think it said one way. So that's 150 feet of 1" pex total plus whatever you have inside the basement plus all your fittings. And pex elbows kill flow pretty good. But if @maple1 is right with your pump being a Taco 007 I don't think you have enough pump. The max head loss on that pump is only 10 ft of head. And I feel like there's more than that on your OWB side.











If you could take the time and write down a list of every fitting and foot of pipe on your OWB side we're might be able to help you figure out the head loss and see if it's over what your pump can handle.




Here's my example of a list of fittings. This is of my system. BV = ball valve, 90° is an elbow (ect.) If you write down a 90° pex elbow make a note of that because like I said they add alot to it.


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## Roundgunner (Dec 26, 2018)

I keep my boiler on till 180 then only let it drop 5 to 175 before coming back on. I also have a lot of fire brick. The 5' differential  might use more wood but my fire never goes out. 

I wonder,  if you are losing that much heat in the pipe maybe buy new well insulated ones run them on the surface and cover them with heybales until spring thaw.


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## maple1 (Dec 26, 2018)

He said he has Thermopex. Cant get much better. Of course, with low flow, some temp will be lost in the uninsulated sections.


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## Mahoney86 (Dec 27, 2018)

I would have to agree with everyone, I definitely believe it is a circulator issue at a minimum. Being that I just bought a new 007F5 pump and I still have the original 007F5 pump, would it be possible to maybe put the spare pump on the OWB return line? Just hate to spend another $250 on this darn thing when I have a brand new pump already


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## maple1 (Dec 27, 2018)

I would try that if I already had the circs.


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## warno (Dec 27, 2018)

Definitely couldn't hurt if you have the hardware already.


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## Mahoney86 (Jan 16, 2019)

Took entirely too long but I finally decided last week, no sense in rigging up 2 pumps and fiddling around with everything so I placed an order for a new circ pump. I was recommended a Taco 009-F5. I can definitely tell this pump can handle more head and push more water then the little 007 pump.

I did fire everything up right after hooking the pump up this week after work on Monday. Fire got lit, it was 25* out so it took a maybe 1.5hrs to get the 43* water up to 150* before I opened up the valves to the HX inside. I still could not get a temp reading from my laser thermos hotter than 150* inside which is worse than then the 170 I was getting before. I am hoping this time around I simply just have air in the system from installing the new pump. I only bled the lines buy flowing water through my indoor purge valves a few times and it all seemed fine. I went to bed that night hearing my oil boiler running most of the night, though I was surprised to wake up to have the fire still going in the wood boiler, however the coal bed was basically nonexisting. I raked things up, loaded her up for the day and went to work. As I suspected, I got home from work 14 hours later and the fire completely went out and the firebox was still completely loaded with wood.

Tonight I will hook up the garden hose and try and push water through the lines from the house into the wood boiler.


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## maple1 (Jan 16, 2019)

Mahoney86 said:


> Took entirely too long but I finally decided last week, no sense in rigging up 2 pumps and fiddling around with everything so I placed an order for a new circ pump. I was recommended a Taco 009-F5. I can definitely tell this pump can handle more head and push more water then the little 007 pump.
> 
> I did fire everything up right after hooking the pump up this week after work on Monday. Fire got lit, it was 25* out so it took a maybe 1.5hrs to get the 43* water up to 150* before I opened up the valves to the HX inside. I still could not get a temp reading from my laser thermos hotter than 150* inside which is worse than then the 170 I was getting before. I am hoping this time around I simply just have air in the system from installing the new pump. I only bled the lines buy flowing water through my indoor purge valves a few times and it all seemed fine. I went to bed that night hearing my oil boiler running most of the night, though I was surprised to wake up to have the fire still going in the wood boiler, however the coal bed was basically nonexisting. I raked things up, loaded her up for the day and went to work. As I suspected, I got home from work 14 hours later and the fire completely went out and the firebox was still completely loaded with wood.
> 
> Tonight I will hook up the garden hose and try and push water through the lines from the house into the wood boiler.



Well, you won't get hotter water in the house than what is in the wood boiler - which was 150? Unless you meant different than what you typed. 

It would make things easier for getting air out, if you simply had a bleed spot to let some out (a ball valve T'd in?), at the high points in your piping & system. If the fire went out with a load of wood inside, that does sound like the heat wasn't going anywhere and it shut itself up. Which does sound like trapped air. As long as the pump was indeed running. And as long as the fire did get itself going to start with.


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## stee6043 (Jan 16, 2019)

Bugger.  I'm still looking forward to you posting that you're running like a champ.

Fortunately, the coldest part of winter is still a few weeks away


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## Mahoney86 (Jan 16, 2019)

Sorry I should have clarified, when I took the 150* temp inside on the pex, the OWB was well over 190* at that point.

I believe the true "high point" of the system would be the wood boiler itself. I do have boiler drain valves added right before the supply and return at the HX. This is normally the spot where I try and bleed air as this is the highest point within the house.

The fire was definitely going, when I went outside at 430am before work I burned everything down from the night before and loaded her up about 3/4 full. At 830am when my wife left for work, she sent me a photo of the condensation coming out of the OWB chimney so the fire at least burned or smoldered until 830am when she left. So somewhere during the day the fire went out.

Im also thinking maybe my wood splits are too large, not allowing for the wood to burn down to form a nice coal bed. When I see pictures and videos of other OWB at reload, the coal beds are huge! One thing I notice is that it is usually difficult to keep a super hot temperature in my reaction chamber. I have heard the e-classics should be running well over 1000* in the reaction chamber, I recent haven't seen a temp in the reaction chamber over 8-900* and normally it hovers in the 650-800 range during heating. Then during normal operation I will see the reaction chamber go down into the 200* range and only up to 400 or so during the idle "purge" every 20 minutes


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## maple1 (Jan 16, 2019)

Mahoney86 said:


> Sorry I should have clarified, when I took the 150* temp inside on the pex, the OWB was well over 190* at that point.
> 
> I believe the true "high point" of the system would be the wood boiler itself. I do have boiler drain valves added right before the supply and return at the HX. This is normally the spot where I try and bleed air as this is the highest point within the house.
> 
> ...



Your last mentions of reaction chamber temps suggests wood that isn't dried enough.

But if the OWB is maintaining 190, that is beside the point for now - that point being, getting that heat, into the house system. So better to focus on one thing at a time here to not cloud issues too much.

A system & piping layout can have more than one high point. Each one should have a way to get air out easy. Because they can all accumulate air into air locking pockets.


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## maple1 (Jan 16, 2019)

A reposting of new numbers similar to post 78 might help.

I also still think the 20 plate HX mentioned earlier would likely be too small to transfer much heat when it comes to heating a house. But without numbers....


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## Mahoney86 (Jan 16, 2019)

I will try giving the lines a solid purge tonight and will post temperature readings as I have done early to see how we are making out.


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## TCaldwell (Jan 16, 2019)

Has the plate hx ever been cleaned?


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## maple1 (Jan 16, 2019)

TCaldwell said:


> Has the plate hx ever been cleaned?



I think its new? Came in somewhere in the middle of the thread? But it's not very big.


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## Mahoney86 (Jan 16, 2019)

Yes the flat plate is new

So got home from work and fired up the wood boiler and turned the heat up in the house

At 7:35pm here are the readings 

OWB display - 183

OWB supply -171
OWB return -156

Oil in - 148
Oil out - 164

Temp gauge on oil boiler 160


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## maple1 (Jan 16, 2019)

Mahoney86 said:


> Yes the flat plate is new
> 
> So got home from work and fired up the wood boiler and turned the heat up in the house
> 
> ...



That is an improvement.

I'd be most concerned about the 12 drop between OWB and OWB supply though? Are you sure the water leaving the OWB is 183 or close to it?


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## Mahoney86 (Jan 16, 2019)

Now here is where the frustration sets in each time.

I pushed water from house to OWB. I opened the purge valves inside and drained 10’gallons of water to see if any other air could be trapped.

It’s now 8:03

OWB reached its high point of 192 and is now idle.
Temp reading at the supply line into HX is now down to 170. So my OWB temp has increased 9 degrees but my temp inside went down! 

My thermostat inside is still calling for heat and everything is circulating


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## Mahoney86 (Jan 16, 2019)

maple1 said:


> That is an improvement.
> 
> I'd be most concerned about the 12 drop between OWB and OWB supply though? Are you sure the water leaving the OWB is 183 or close to it?



Yes that is extremely concerning to me. Went I take a temp reading at the pump casing it is 180 degrees. When I remove the pipe insulation and shoot a temp reading on the pex it is low 170s

My outside temp right now is only 39 degrees.


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## Mahoney86 (Jan 16, 2019)

1 hr later update 

830pm


OWB temp at display -180


OWB supply - 163
OWB return - 152

Oil in - 143
Oil out - 156


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## Mahoney86 (Jan 16, 2019)

Did another quick check and display on OWB is reading 185 and OWB supply is at 168 climbing and my house system is still circulating so I feel like if any air was present it should likely be gone now.

Now it seems the next item of concern is the massive temp loss from the OWB to the house. There is a 7-8” run on the supply side that is not insulated in my basement, other than pipe insulation I have not insulated anything else on the OWB itself.


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## maple1 (Jan 16, 2019)

Simple question. 

What is the temp of water right where it enters the pipe leaving the OWB, vs what the OWB display says, vs what is entering the HX from the OWB, at any one time? I couldn't discern that from your posts.


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## Mahoney86 (Jan 16, 2019)

Heat loss continues to grow if I raise the hi point as well. I raised to 195 and the OWB immediately went to 202 degrees. Inside supply at HX is 184 now

I guess the bright side of it all is I now know why my oil burner runs all night when set to a high of 170. Clearly the OWB heat loss is making it unattainable for my oil boiler water lines to get even close to 160 never mind 170.

That also explains why the OWB fire continually goes out because there is no need for it to heat water as the oil boiler is running consistently to keep up with the heat demand. I can lower my oil boiler hi point to 150 but then cold showers will be instore


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## Mahoney86 (Jan 16, 2019)

maple1 said:


> Simple question.
> 
> What is the temp of water right where it enters the pipe leaving the OWB, vs what the OWB display says, vs what is entering the HX from the OWB, at any one time? I couldn't discern that from your posts.


Display right now reads 202*

The metal elbow directly outside the boiler reads 197*

The area where the water pushes the circ pump reads 200*

The pex piping below reads 190*


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## maple1 (Jan 16, 2019)

Mahoney86 said:


> Heat loss continues to grow if I raise the hi point as well. I raised to 195 and the OWB immediately went to 202 degrees. Inside supply at HX is 184 now
> 
> I guess the bright side of it all is I now know why my oil burner runs all night when set to a high of 170. Clearly the OWB heat loss is making it unattainable for my oil boiler water lines to get even close to 160 never mind 170.
> 
> That also explains why the OWB fire continually goes out because there is no need for it to heat water as the oil boiler is running consistently to keep up with the heat demand. I can lower my oil boiler hi point to 150 but then cold showers will be instore



I would lower that 170 to at least 160 when running the OWB. Mine would make enough DHW down to 140 or less. Do you have a tankless coil or an indirect?

I'm at a loss on the temp drop to the HX. If water wasn't flowing you'd see a big temp drop thru that side of the HX.


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## maple1 (Jan 16, 2019)

You said above you purged 10 gallons. Not sure your setup for doing that or how you're doing it - but is there a way you can run the OWB circ with the return running into a bucket so you can measure the gpm it is pumping? Not sure if even possible. 

Or maybe before that, measure temp of OWB water as it exits the HX, vs its temp right before it enters back into the OWB.


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## warno (Jan 16, 2019)

I just quickly went back through the pages on this thread. Could we get a picture of the back of the OWB? I'm curious if you are pulling OWB supply from the top or bottom of the water jacket.


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## Mahoney86 (Jan 16, 2019)

warno said:


> I just quickly went back through the pages on this thread. Could we get a picture of the back of the OWB? I'm curious if you are pulling OWB supply from the top or bottom of the water jacket.


Water is being pulled from the top where central boiler indicates hot water supply. Return from HX is at the bottom


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## warno (Jan 16, 2019)

I guess the temp probe must be higher than the supply port then. But that's irrelevant now if you're pulling from the top port.


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## warno (Jan 16, 2019)

@Mahoney86 I'm alittle worried you might still have a lack of flow to your FPHX. I looked up the pump curve and it's definitely a high head circ but at best you're going to get 10 gpm.










Did we ever get a good estimate head loss on your OWB side of your system?


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## maple1 (Jan 17, 2019)

warno said:


> @Mahoney86 I'm alittle worried you might still have a lack of flow to your FPHX. I looked up the pump curve and it's definitely a high head circ but at best you're going to get 10 gpm.
> 
> View attachment 238457
> 
> ...



I woke up this morning thinking about this thread (arrrghh) - and I think you could be right. If the lines are all well insulated, and temp readings are accurate, that is the only reason I can think of for the apparent loss between the OWB & the HX. And now after seeing it, that isn't an overly impressive pump curve for decent flow.

We also haven't seen many if any pics of the whole OWB loop - particularly of the boiler/circulator area & plumbing of it. If the circ is close to the top of the OWB, there might also be some cavitation potential.

I think it is also hard to fully get a read on things, from the HX temps, because the HX is also likely quite undersized (20 plate?). So what looks from the temps like decent flow, might actually not be because the HX isn't big enough to transfer out a lot of heat.

And we also don't know how well the indoor side of the HX is doing. Or circulating. I think I remember one pic showing the HX on its back - not sure how much that impacts, but pretty sure mounting in that position isn't recommended. Might be for scaling reasons. But if that side isn't flowing a lot, that could also make for misleading temp readings.


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## stee6043 (Jan 17, 2019)

It's a shame we don't all live in NY/NJ.  I'd love to see this thing running in person.

You guys might be right on this pump thing but I've been struggling with the idea of "not enough flow" since the beginning of this thread.  Mahoney isn't pumping this water particularly far...and only through a single HX.  I feel like there is something plumbing related still going on here.

Mahoney, if you were to let the oil boiler run and isolate the OWB what would your supply and return temps be at the OWB?  With no heat load you should be able to send water to your house and back and only lose a few degrees.  Did you potentially install a bypass that would enable you to do this kind of recirc into the house and directly back into the OWB?  Any chance your thermopex is waterlogged or crushed/restricted?  Just for kicks have you opened up a spigot on your OWB loop inside the house to confirm you're getting "very good flow" from that thermopex?


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## warno (Jan 17, 2019)

@stee6043 if I remember correctly the underground run was 75 feet I believe one way. So that's 150 feet of 1" pex.  plus i remember seeing alot of pex 90s in the other pictures on the OWB side. 75 feet isn't far but, correct me if I'm wrong, my findings say that's alittle over 12 feet of head in the underground alone.


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## Eureka (Jan 17, 2019)

I just read through all of this, but was the circulator loop added from the plate exchanger to the oil boiler to keep the temperature up?  Without doing that I simply don't see how this will ever work without your oil boiler constantly firing to maintain it's temp.  The oil boiler might not ever get up to temp just by circulating through the plate exchanger when there is a thermostat call for heat, especially given the fact that the load will always be sucking up all the heat.

You keep losing fires in your OWB because there is hardly ever any load on it because the oil boiler is heating your house most of the time. Without a circulator always pushing water through the plate exchanger you're really only heating up the first couple feet of the oil boiler copper piping right next to it.  You want to be pushing water in and out of your oil boiler water jacket to keep it heated and up and ready for a call for heat.  The constantly running circulator will then heat the jacket right back up to near OWB temp as soon as the heat call is satisfied and the existing oil boiler circulator shuts off.  This would mean always having DHW water ready too.

My take at least.  Seems like it should work just fine after that.


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## Eureka (Jan 17, 2019)

I forgot but also wanted to add that I REALLY wouldn't count on an IR thermometer to get accurate readings of water temps.  You really need to have a temperature gauge placed in a tee so it's seeing actual flow.  I have learned this first hand.  Sharkbite makes a handy temperature gauge that's easy to slip in but very $. I just used cheap Watts gauges in black/brass pipe tees so the thermowell is right in the middle of the flow.  Works perfectly.

I have just learned that an IR gun reads all over the place especially on different surfaces, black paint/tape or not, of different materials that transfer heat differently.  They're really only good if you have a known actual baseline temperature to set a differential from.


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## maple1 (Jan 17, 2019)

Eureka said:


> I just read through all of this, but was the circulator loop added from the plate exchanger to the oil boiler to keep the temperature up?  Without doing that I simply don't see how this will ever work without your oil boiler constantly firing to maintain it's temp.  The oil boiler might not ever get up to temp just by circulating through the plate exchanger when there is a thermostat call for heat, especially given the fact that the load will always be sucking up all the heat.
> 
> You keep losing fires in your OWB because there is hardly ever any load on it because the oil boiler is heating your house most of the time. Without a circulator always pushing water through the plate exchanger you're really only heating up the first couple feet of the oil boiler copper piping right next to it.  You want to be pushing water in and out of your oil boiler water jacket to keep it heated and up and ready for a call for heat.  The constantly running circulator will then heat the jacket right back up to near OWB temp as soon as the heat call is satisfied and the existing oil boiler circulator shuts off.  This would mean always having DHW water ready too.
> 
> My take at least.  Seems like it should work just fine after that.



Yes, that may be at play too. But seems from the postings that the heat isn't making it from the OWB to the HX the way it should be. Which should be the first thing to get sorted & working right.


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## Eureka (Jan 17, 2019)

I guess I just think the temperature readings might not be close to actual and maybe are mistakenly being focused on.  It seems like the OWB side is pretty straightforward as long as the supply/return are correct.  I'm using a similar OWB circulator going through two plate exchangers, a Caleffi thermostatic valve, and another 40 feet of underground, and even if I put it on low speed, it still transfers plenty of heat (albeit with a huge delta T). 
I could see a different circulator making it run more ideally but it should still function at some level which it doesn't seem to be doing now.


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## maple1 (Jan 17, 2019)

Eureka said:


> I guess I just think the temperature readings might not be close to actual and maybe are mistakenly being focused on.  It seems like the OWB side is pretty straightforward as long as the supply/return are correct.  I'm using a similar OWB circulator going through two plate exchangers, a Caleffi thermostatic valve, and another 40 feet of underground, and even if I put it on low speed, it still transfers plenty of heat (albeit with a huge delta T).
> I could see a different circulator making it run more ideally but it should still function at some level which it doesn't seem to be doing now.



Without being there we are all doing a bit of guess work, and relying on the OP for info to try to help. Temp readings are about all we have, and should be good info if accurate. Pictures sometimes help too but we don't have many of those.

How big is your underground? What do you have exactly for a circ? Even if the same, there could be other varying factors at play here that might show in a picture. Layouts can differ quite a bit & influence if something gets overlooked or not done right. 

A good dual probe BBQ thermometer can also be really good for this work. Tie each probe onto a pipe entering & leaving something, under some pipe insulation, and you get a pretty accurate read of temps. I have a Maverick on my tanks, it is very accurate. One thing I don't think that has been done here yet, is measure the temps of water leaving the OWB, and coming back to it - both with the oil side not circulating, then with it circulating. With the oil side not circulating, there should not be a big difference around the whole loop, with good OWB flow and well insulated piping. That would be my step 1 - then work towards the indoor stuff.


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## warno (Jan 17, 2019)

Eureka said:


> I guess I just think the temperature readings might not be close to actual and maybe are mistakenly being focused on.  It seems like the OWB side is pretty straightforward as long as the supply/return are correct.  I'm using a similar OWB circulator going through two plate exchangers, a Caleffi thermostatic valve, and another 40 feet of underground, and even if I put it on low speed, it still transfers plenty of heat (albeit with a huge delta T).
> I could see a different circulator making it run more ideally but it should still function at some level which it doesn't seem to be doing now.



A similar setup in plumbing with a different circulator makes all the difference in the world. I don't believe the Taco 009 that the OP said they just installed is a multi speed pump. When I looked up the manual to get the curve it only showed one speed and a flow of 10 gpm max. Which isn't a whole lot when trying to heat a house, essentially, through a 20 plate HX.

And @maple1 made a good point earlier that the OWB circ may be cavitating. Any cavitation will create lack of flow also.


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## Eureka (Jan 17, 2019)

I'm late to the party and just trying to be a fresh set of eyes to help this guy stay warm and enjoy his investment of money and I'm sure lots of time as well.  I like to make sure the basics are covered first and that recirculating loop through the oil boiler seems like a basic component of his system.

I still agree with what everyone else is saying and much of what I have learned in the last couple years has been from some of the fine minds in this thread.  My trial and error building two systems has taught me even more.  I've also learned that it's easy to focus on the wrong things when they're the only things available to look at.

I use Steibel Eltron circulators that are basically a Grundfos 15-58 3 speed.   1-1/4" underground lines but it all transitions to 1" inside my buildings.  The one to my house I run on high to keep around 20-30 delta T and one to the shop is on medium.  I have very few elbows and fittings and come into and out of my plate exchangers straight rather than directly into elbows, thanks to my research here. 

So yes my situation is different, but I still think something very basic is missing in this system because it doesn't work at all.  We can only help the OP as much as they are willing to help themselves by providing lots of info and pictures.


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## warno (Jan 17, 2019)

@Eureka nothing wrong with another set of eyes. I'm basing all my experience of my system in the past 4 years and alot of reading here. I know that when I redid my plumbing and went to a much larger HX everything fell into place. When I dropped more than half the head losses and the addiction of a bigger 90 plate, vs. My 20 plate I had, I arguably dropped all my problems.


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## Mahoney86 (Jan 17, 2019)

Thank you for all the help in this everyone I’m truly blessed to have all of this input.

As suspected came home from work today to the fire completely out and wood barely even charred.

My indoor boiler is set to 150 and my OWN temp display is showing 148 right now.

I took some photos of the indoor setup. Disregard the small 3/4” pex lines. Not really sure what anyone wants to see so just let me know and I will take pictures.

I have no installed any circulator from the HX to my domestic water loop or anything like that. Before I even go down that road i need to solve other issues. Regardless I am likely going to disconnect my DHW from the oil boiler and install a natural gas tank heater as we just got natural gas installed at our house for free as an incentive from the gas company as they recently ran lines in the street. We can talk about hooking that heater in at another time.

All the pex is 1”. I have (2) 90* elbows on each owb line for a total of 4 elbows. The inlets on the HX are 1 1/4” and the HX is rates to 280,000 btu according to the spec sheet. Amazon will let me return the 009 series pump so if I need to upgrade to an 011 then it is what it is at this point. 

I will be out of town this weekend at my camp and there is a central boiler dealer local. If I need to grab any supplies I can easily do so


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## maple1 (Jan 17, 2019)

Pics of the OWB setup?

Can you describe your OWB line purging method, exactly? Those 90s above the HX are prime air trapping spots.


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## warno (Jan 17, 2019)

@Mahoney86 could I see a picture of your OWB plumbing at the boiler itself? 

Also how long exactly is your underground run, 1 way, to the home and how many feet of pex are in the home before the FPHX?

I think the 0011 circ would be better but there might still be a better option. Are you dead set on buying a Taco circ?


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## Mahoney86 (Jan 17, 2019)

Back of OWB photo

I have 75’ of 1” thermopex prior to going through my foundation wall. Then I have another 8’ of 1” pex line before the HX. Same amount on the return line. 

Circulator brand doesn’t matter to me, just stayed with taco as it’s the most commonly found and fastest delivery


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## warno (Jan 17, 2019)

I went with 200 total feet of 1" pex to cover underground, in home, in boiler cabinet, and elbows. I found that elbows add about 10 feet each of head loss. So I just rounded back to 200 feet total. I went with 8 gpm for the math. Here's the site I used to get it.

200 feet at 8 gpm
3.68(per 100ft 1" pex)  x 2 = 7.36 psi loss
7.36 x 2.3 = 16.92 head loss

1 psi = 2.3 ft of head

With more flow your head loss goes up. so be sure to size a circ that work for your desired gpm. If you go with that 0011, it can run about 16 gpm at 17 ft of head. But remember your head goes up with flow and I did that math based on 8 gpm.

Anybody want to double check my math. I don't want to steer anyone wrong.


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## maple1 (Jan 18, 2019)

There would also be pressure drop from the HX. Not sure how much that would amount to. I think I'm now thinking that the 009 should be doing better than it seems to be.

It might work better if it was mounted lower - there isn't much water above it to give it good inlet pressure. Does it make any noise when it is running?

I am still suspicious about some air in the lines. Maybe even in the HX itself. The way that HX is oriented & plumbed, and the location of all the valves there, is making for real good air trap potential.


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## TCaldwell (Jan 18, 2019)

I agree with maple on the air, how much trouble would it be to disconnect the return at the owb , energize the circ and fill a 5 gal bucket till it runs air free? That could also help determine flow rate. If the air is back at the hx, it could take 5 gal before you’d see/hear it come out. If that is successful then put your efforts to the pressurized side


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## Woodman1 (Jan 18, 2019)

Your math looks ok but 8 gpm would be the upper limit for 1" pex. Anything beyond that would push head loss and water velocity to the point of causing other issues


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## Mahoney86 (Jan 18, 2019)

Just unhooked my return side and ran a
Little over 5 gallons out. Didn’t see anything crazy indicating air but maybe it did the trick


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## Eureka (Jan 18, 2019)

It’s a pain in the butt, but if you could do that again and time exactly how long it takes to fill 5 gals, it’ll help your diagnosis greatly.  If you have water treatment in the OWB just use a nice clean bucket and dump it back in.


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## stee6043 (Jan 18, 2019)

Mahoney86 said:


> Just unhooked my return side and ran a
> Little over 5 gallons out. Didn’t see anything crazy indicating air but maybe it did the trick



Was the water hot (within a few degrees of supply)?


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## maple1 (Jan 18, 2019)

Mahoney86 said:


> Just unhooked my return side and ran a
> Little over 5 gallons out. Didn’t see anything crazy indicating air but maybe it did the trick



Little details can get lost in internet talks.

Where did you unhook it exactly? Boiler circ was running when you did it? No other sources of water or water flow at play when you did that? Should top the OWB up with water before you do it so it won't get too low while doing it.

And as suggested above - when you do that, time the flow or bucket filling to get a GPM idea. And watch & report on temps - the water coming into the bucket should be almost as hot as the water leaving the boiler. After you get a couple gallons through. Well, no, that's not quite right. If starting when there has been no flow for a while, it will likely take a couple buckets running through it before all the water in the pipe gets purged and things get close to heat soaked.


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## TCaldwell (Jan 19, 2019)

Anything figured out yet?


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## maple1 (Jan 19, 2019)

TCaldwell said:


> Anything figured out yet?



I think he was going away for the weekend.


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## Mahoney86 (Jan 22, 2019)

maple1 said:


> I think he was going away for the weekend.



Correct I was away for the weekend and of course it was the coldest days of the year! I hoped to get the boiler going last evening but I lots and lots of vacation traffic made my ride home much longer than anticipated. Hoping I can fire it up tonight after work, but its not looking so good.

Good news is I am working from home on Thursday so that will give me some time to really keep an eye on the boiler. Unfortunately I am expecting temperatures over 50* for Thursday.


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## TCaldwell (Jan 22, 2019)

My bad,


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## maple1 (Jan 22, 2019)

TCaldwell said:


> My bad,



Pfft, that wasn't bad...


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## Mahoney86 (Jan 24, 2019)

Waiting for the down pouring rain to stop before I disconnect my return line to see how long it takes to fill 5 gallons. In the meantime I took a sample of water out of the drain valve on my supply line right before the heat exchanger and the water temp is 174* where the OWB display is showing 203*


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## TCaldwell (Jan 24, 2019)

Just to complicate things a little more, if there hasn’t been flow through the owb lines for awhile, they get cold and takes more time than you’d think to get them warmed up to get the actual water temp


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## Mahoney86 (Jan 24, 2019)

TCaldwell said:


> Just to complicate things a little more, if there hasn’t been flow through the owb lines for awhile, they get cold and takes more time than you’d think to get them warmed up to get the actual water temp



Agreed. I actually didn’t close any of the bypass valves while I was gone for the weekend so the water in the OWB and the lines remained at 140-150


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## Mahoney86 (Jan 24, 2019)

Ok the monsoon rains have stopped so I went out and disconnected the supply line at the wood boiler. Its amazing how much water gets pushed out just due to head pressure from the OWB being above the basement level.

Anyways with the pump plugged in I was able to fill a 5 gallon bucket in 33 seconds. So with my math that is 6.6gpm I am pushing through my HX.


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## maple1 (Jan 24, 2019)

The supply line? Or the return line?


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## Mahoney86 (Jan 24, 2019)

The water was taken from the return line right where it would connect to the OWB


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## TCaldwell (Jan 25, 2019)

Have you bypassed or removed the expansion tank?


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## maple1 (Jan 25, 2019)

Mahoney86 said:


> Ok the monsoon rains have stopped so I went out and disconnected the supply line at the wood boiler. Its amazing how much water gets pushed out just due to head pressure from the OWB being above the basement level.
> 
> Anyways with the pump plugged in I was able to fill a 5 gallon bucket in 33 seconds. So with my math that is 6.6gpm I am pushing through my HX.



The only head pressure would be from the height of the OWB water above the fitting you unhooked. If that is 3', it would only be 1.2 psi. An isolation valve at the OWB outlet would make it less messy.

And actually I think that is 9gpm by the math.

There is something strange going on here that I don't think we can help sort out any more, without actually being there. 9gpm should be moving all kinds of heat to the HX. Something is not jiving, in the info or how things are being done.

Why do you have that bypass leg in front of the HX? Are you sure nothing is going through that? It was closed when you did the bucket thing?

EDIT: There could be inaccuracies in the temp measuring too depending on how its being done. I see shiny fittings & surfaces & no flat black spray paint.


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## Dutchie84 (Jan 25, 2019)

Mahoney86 said:


> Ok the monsoon rains have stopped so I went out and disconnected the supply line at the wood boiler. Its amazing how much water gets pushed out just due to head pressure from the OWB being above the basement level.
> 
> Anyways with the pump plugged in I was able to fill a 5 gallon bucket in 33 seconds. So with my math that is 6.6gpm I am pushing through my HX.



I would check you math again. It more like 9 gpm. 


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## Dutchie84 (Jan 25, 2019)

Maple beat me too it


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## TCaldwell (Jan 25, 2019)

The reason I ask about the isolating the expansion tank is that it was recommended to me, as I’m non pressurized as well.


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## maple1 (Jan 25, 2019)

TCaldwell said:


> The reason I ask about the isolating the expansion tank is that it was recommended to me, as I’m non pressurized as well.



Is your whole system non-pressurized? 

This one has an HX in place now. I think. So expansion tank should still be at play, on the oil/pressurized side.


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## Mahoney86 (Jan 25, 2019)

The expansion tank is still in place as the indoor system is still pressurized. My OWB is a complete separate open system due to the addition of the HX.

Maple, the little blue bypass leg is there so that when the OWB is not in use (away for a long weekend) I can close off the flow going through the HX so that I am not wasting oil heat maintaining the boiler temperature.


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## TCaldwell (Jan 25, 2019)

Maybe I’m missing something, but looking back at the pictures I don’t see a circ moving the heat out of the flat plate to the set of closely spaced t’s and back to the flat-plate?


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## Eureka (Jan 25, 2019)

It’s relying on the oil boiler circulator to push the return water through the plate exchanger on a thermostat call for heat.  Kind of why I don’t see this working well to preheat the oil boiler because there’s nothing keeping heat transfer going when the thermostat is satisfied.


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## TCaldwell (Jan 25, 2019)

I believe that’s the problem, the closely spaced t’s I believe should be on the return to the oil boiler with a circ between the flat plate and closely spaced t’s that is powered the same as the unpressurized owb circ?


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## maple1 (Jan 25, 2019)

But the primary problem right now - I think (this thread has gone in a few circles) - is that the heat isn't getting from the OWB to the flat plate to start with.

As far as we know.

That should not be a problem if that loop is flowing at 9gpm.

Yes, I think the oil side of the HX could be done better. But getting past that first issue has been hard to do. For some reason.

IMO either the GPM measuring exercise, or the temp measuring exercise, isn't accurate. Or there is some other problem in the one simple loop that hasn't been made apparent yet.


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## Dutchie84 (Jan 25, 2019)

Like Maple said, was the bypass open when you did your flow test?


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## Eureka (Jan 25, 2019)

I agree @maple1 
From the info we have, it appears OP is losing around 29 degrees to the ground, at 9 GPM.  I stand by my suspicion of inaccurate temp readings being a contributing factor here.  If it is indeed Thermopex, that’s impossible unless the installation was seriously compromised and the outer casing and foam are missing in a large area.


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## TCaldwell (Jan 25, 2019)

I thought with posts 149/150 flow estimated to be 9gpm, even at 6.6 a low calculation round trip from the owb through the flat plate and back to the return port of the owb, wouldn’t explain his problem. But what would explain is if there was poor flowthrough the pressurized side of the flat plate, relying on zone flow circs to make that happen.


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## Mahoney86 (Jan 25, 2019)

The Bypass was not open during the flow test. Everything was kept normal to allow for full flow through the HX.

Can someone steer me in the right direction of what I should be doing plumbing wise on my oil boiler return? It was my understanding on this thread that I should have done exactly what I did but Teeing off the HWBB return and T back into the return on my Oil Boiler.

I would agree with the statements that my Oil Boiler is not staying hot and it turns on all of the time. I would agree this thread is going in many many directions, but I have tried my best to take peoples advice here and install as told. If I installed something incorrectly let me know I will make modifications.

 I stopped using the infrared gun to take heat readings. I am now using my BBQ Thermopen and measuring the actual water temperature


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## maple1 (Jan 25, 2019)

TCaldwell said:


> I thought with posts 149/150 flow estimated to be 9gpm, even at 6.6 a low calculation round trip from the owb through the flat plate and back to the return port of the owb, wouldn’t explain his problem. But what would explain is if there was poor flowthrough the pressurized side of the flat plate, relying on zone flow circs to make that happen.



That wouldn't explain the big temp drop though from the OWB to the HX? It should only be a couple or very few degrees - he's got 20.


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## maple1 (Jan 25, 2019)

*I am now using my BBQ Thermopen and measuring the actual water temperature*


How are you able to get that into the water?


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## maple1 (Jan 25, 2019)

Mahoney86 said:


> Can someone steer me in the right direction of what I should be doing plumbing wise on my oil boiler return? It was my understanding on this thread that I should have done exactly what I did but Teeing off the HWBB return and T back into the return on my Oil Boiler.



I think that was suggested as the easiest way. And it should work. But it would depend on how steady your oil boiler & heating zones circulate. Since the HX won't transfer anything when the oil side isn't circulating.

And it would also depend on the ability of your HX. Which IMO is undersized (I would use one 4x the size). And it is also not oriented properly.


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## TCaldwell (Jan 25, 2019)

I understand your frustration and appreciate your patience, can we all agree on a flow rate of 6.6 to 9 gpm round trip on the owb side? Maples concern of a 20 degree drop round trip with no load should be the next to beat  to death. 
 Can you shut off all loads and isolate the owb loop and let run for 20 minutes or so and measure temps at outlet from owb and return at owb. That should give a good sense of temp change on that loop, if good we can move on if not it’s probably a hx issue. 
 I agree with maple the hx orientation isn’t right


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## warno (Jan 25, 2019)

If you are flowing 9 gpm, 5 gallon bucket - 30ish seconds, there shouldn't be this big of problem to get heat from the OWB to the oil boiler through the FPHX. other than the HX itself is limiting it a 20 plate is honestly small for what you are doing. But the large delta T on the OWB side is telling me there isn't quite that much flow. 

When you did the bucket test did you have the circ running with the return line on the outside of the bucket then move it into the bucket right when m toy started the timer? Because I believe you mentioned the amount of water pushing out of the line was alot. I'm wondering if you maybe started filling off of the gravity in the water jacket before starting the circ. 

Another thing I'm wondering,  and maybe someone smarter than me can say yes or no, if you open the return line on an open system it's going to start "draining" the boiler. Could it be possible the water level would push past the circ and give a higher flow rate than what is happening while the circ is running?


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## Mahoney86 (Jan 25, 2019)

When I did the flow test I plugged the pump in without a bucket underneath and then as it was flowing moved the bucket into the flow path of the OWB return water.

When I get home this evening, I will fire up the boiler again ( we all know that it is out again since this thing is getting no load) and bring up to temp. I will then be sure my oil boiler is off and I will open the purge valves at the HX and take temp readings of the actual water with the thermo pen.


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## Mahoney86 (Jan 25, 2019)

OWB is up to temp and currently at 200* on display

Inside temp of the actual water ( coming out of the purge valve on both. The supply and the return are both measuring 187* with no load on the indoor system at this time.


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## TCaldwell (Jan 25, 2019)

How long did it take to get to 187, if you let it run longer does the temp rise at all? The fact that both are the same temp is a good sign. Could it be possible the sensor for the boiler display is located higher than where you are taking the purge valve temp?


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## maple1 (Jan 25, 2019)

Mahoney86 said:


> OWB is up to temp and currently at 200* on display
> 
> Inside temp of the actual water ( coming out of the purge valve on both. The supply and the return are both measuring 187* with no load on the indoor system at this time.



That is a different outcome than we previously saw. Time to move focus to the other side of the HX,  I think. Get it opened up and running and measure temps again.


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## warno (Jan 25, 2019)

I agree with @TCaldwell. The temp probe on the OWB is probably in the water jacket higher than the supply port. It doesn't take much to height to make a difference. I would say you need to try circulating the oil boiler water through the FPHX continuously as long as the OWB is running. Maybe it's just not putting the heat into the boiler often enough because it's only circulating with thermostat call.


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## maple1 (Jan 25, 2019)

warno said:


> I agree with @TCaldwell. The temp probe on the OWB is probably in the water jacket higher than the supply port. It doesn't take much to height to make a difference. I would say you need to try circulating the oil boiler water through the FPHX continuously as long as the OWB is running. Maybe it's just not putting the heat into the boiler often enough because it's only circulating with thermostat call.



I think the main issue, if we do indeed have OWB water running well thru the HX, is the HX is too small.


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## TCaldwell (Jan 25, 2019)




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## TCaldwell (Jan 25, 2019)

Sorry the above pic is not very clear, but I believe this concept would work


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## TCaldwell (Jan 25, 2019)

Tap on the pic, much clearer and expand


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## maple1 (Jan 25, 2019)

Won't that only work when the zones are flowing? Same as cuŕrent setup? I might be missing something.


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## TCaldwell (Jan 25, 2019)

Possibly a small bypass circuit between the top of the boiler and zone returns with a circ and ball valve, just to keep supply water flowing through boiler


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## TCaldwell (Jan 25, 2019)

How about this, bypass just past Antron air purge to zone return, probably 1/2 inch with a low flow circ and ball valve?


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## warno (Jan 25, 2019)

@TCaldwell doesn't the OP need to circulate the oil boiler loop through the FPHX to maintain a higher temp in the oil boiler to keep it from firing? Or am I missing something?


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## TCaldwell (Jan 25, 2019)

Yes, with the owb circ, he needs another circ on the pressureized side of the hx and also a small Oiler bypass loop that all run as long as the owb has the temp
 Those 3 wood circs run 24/7 to keep the Oiler hot, when the Oiler can’t make temp, the oil boiler will kick on.
Open for ideas?


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## warno (Jan 25, 2019)

Yes. That's what I'm assuming needs to happen also.

A circ on the OWB that runs to and from the FPHX. That runs 24/7. Or if batch burning, shuts off with end of cycle.

A circ on the oil boiler that runs to and from the FPHX. That runs Same as the OWB side.

Then a circ to feed the zones.

@Mahoney86 I understand the frustration you're going through. It's  difficult on both ends trying to diagnose problems over the internet. I went through this all last season with my system. I know it seems like alot of running back and forth checking the same things over and over but like I said it's difficult with not being able to see it first hand.


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## maple1 (Jan 25, 2019)

HX is not big enough.


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## TCaldwell (Jan 25, 2019)

That’s possible but we don’t know what his loads are either, aside from this do you have a opinion on the piping?


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## maple1 (Jan 26, 2019)

I don't think enough is known about the existing system to come up with a good suggestion. The above is a quick off the cuff thought. The oil side HX loop circ (0010?) would run whenever the wood side one does. When it is doing that, the heat would either go right to loads if a heat demand, or thru the oil boiler (backwards) to keep that hot. Or maybe split some depending how much the loads need. But not sure if it would keep the oil hot enough to stop from it cutting in, if the loads were drawing all the time. So that oil side hot out of the HX could maybe be plugged right into the side of the boiler instead of the supply piping - don't know what it has for available tappings.

(Also I think the drawing has some inaccuracies - it is zoned by circs whereas the system in question I think has one load circ [which I attempted to scribble in] & zone valves?)

But - I think the current setup, with the HX in the return line, could work simply by putting a (much) bigger HX in (and fixing its orientation while at it). That does depend though on heat load & how much time the zones spend in a heat call. IMO a 20 plate is way insufficient for anything other than a lighter DHW heating load.

(Just ask Warno  )

There are no doubts lots of ways this can be done. That's why I was trying to think one step at a time through this. We seemed to have gotten way bogged down in the first simple loop/step - maybe just from temp inaccuracies.


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