Fustrated with OWB

[92rslt1]

Here are some pressure drop numbers from Viega, I imagine other brands would be similar.

I agree that 7.5 GPM is right at 4 feet per second velocity. Exceeding that and you start to get velocity noise and excessive wear in the fittings, especially those close turn ells.

At a 20° ∆T you could expect about 75,000 BTU delivered. If the building heats fine with the 130,000 gas boiler, call it 105,000 at 80% efficiency, you are not going to be able to move that much energy from the OWF. You may sneak up on it a bit by upsizing the pump, but will will have excessive velocity.

By far the most common error we see on this site is undersizing the pex from OWF to the loads. You are covering a portion of the load, on mild days you may be fine, so the rest of the wood is heating the great outdoors from where it came

Thats really strange that CB recommends and installs most of their boilers with 1 inch, but your correct, I was looking at generic flow data and it was saying you get about 10,000 btu per 1gpm. I honestly think if I could get 75k btu it would work OK if the temp was high enough in the baseboards. I would be happy at 75k delivered. I bet now its probably closer to 40k or less.

You have a circulator not a pump.

You have too much operating water pressure in the boiler.

Your circulators need to be pulling water off the top of the boiler not pushing it into the sump of the boiler.


The point of no pressure change is where your bladder tank is located in your system.

Where is your air scoop?????


Ideally you want to pipe the boilers in series then to the heating load then from the return header back to the boiler or boilers
Can you install a domestic hot water coil in the fossil fuel boiler??

Are you able to bypass the wood boiler when the heating season ends??

You have to much plumbing and that is making a mess of things

A simple one pass circular domestic hot water coil would solve most of your issues.

By the looks of your system replacing it with a storage tank would solve all most all your heating issues and eliminate the HX mess completely

The air scoop is there, its just been mounted incorrectly- vertically so it isn't doing anything. I didn't set up up that way, but am going to change when I re-plumb the house boiler or upgrade it. I haven't yet because Im kicking around the idea of a 95% wall mount model and having it installed. Theres an auto bleeder on the outbound manifold.

What do you mean by series? I don't want the water from outside mixing with water inside the gas boiler.
They(CB) run them from water heater to boiler exchanger, back to wood boiler.
.
I added the ten plate because the water heater is only 40 gallon and with 4 showers and laundry every day the 40 gallons goes quick. The 10 plate preheats it so its endless hot water, whereas the side arm keeps it hot once its in the tank, so the water heater never kicks on when its idle. That 10 plate is surprisingly powerful. With a flow rate of 6GPM, I am going to remove it though.

The large exchanger is 60gpm, so I see no restriction there.

So, the gas boiler thats here now has a long story behind it. The way it is installed is not by desire.
The short story is this.
I bought the house foreclosed as a new build that after ten years was never finished, the guy went bankrupt, it sat 7 years empty. All the Baseboard lines were frozen and broke in the basement. The guy had an identical laars teldyne mini furnace, same size and model except it was a thermal draft furnace. You would fall out of your chairs if you saw how it was installed and operating. It was horizontally vented with dryer vent... He also had a 95% efficient 90k btu lp forced air in the office attic, and another 90k lp forced air in the attic of the upstairs with an ac unit attached and a coal stove in the basement. He took the forced air/ac and coal stove when he left. It was pretty obvious he never got the radiant heat working right.

I saw the death trap draft furnace and I had only 3 days to get the house heated for appraisal. I had 3 estimates and then I had them replace it with an exact model, except it was induced draft. The contractors all agreed it would heat the house without any trouble and it does. It was obvious the old boiler plumbing was not correct at the boiler, but I didn't have time to rip it out and start over, the new mini was slid in, converted to lp,inspected for gas leaks, filled and fired the night before appraisal. Its always worked really well despite the wonky pump flow.

I really appreciate all of this help. It seems I most certainly came to the correct place. I have identified several problems and appreciate all the feedback.

According to the Taco manual, this puts me in the 0011 pump selection category.

 

[leon]

Thats really strange that CB recommends and installs most of their boilers with 1 inch, but your correct, I was looking at generic flow data and it was saying you get about 10,000 btu per 1gpm. I honestly think if I could get 75k btu it would work OK if the temp was high enough in the baseboards. I would be happy at 75k delivered. I bet now its probably closer to 40k or less.


The air scoop is there, its just been mounted incorrectly- vertically so it isn't doing anything. I didn't set up up that way, but am going to change when I re-plumb the house boiler or upgrade it. I haven't yet because Im kicking around the idea of a 95% wall mount model and having it installed. Theres an auto bleeder on the outbound manifold.

What do you mean by series? I don't want the water from outside mixing with water inside the gas boiler.
They(CB) run them from water heater to boiler exchanger, back to wood boiler.
.
I added the ten plate because the water heater is only 40 gallon and with 4 showers and laundry every day the 40 gallons goes quick. The 10 plate preheats it so its endless hot water, whereas the side arm keeps it hot once its in the tank, so the water heater never kicks on when its idle. That 10 plate is surprisingly powerful. With a flow rate of 6GPM, I am going to remove it though.

The large exchanger is 60gpm, so I see no restriction there.

So, the gas boiler thats here now has a long story behind it. The way it is installed is not by desire.
The short story is this.
I bought the house foreclosed as a new build that after ten years was never finished, the guy went bankrupt, it sat 7 years empty. All the Baseboard lines were frozen and broke in the basement. The guy had an identical laars teldyne mini furnace, same size and model except it was a thermal draft furnace. You would fall out of your chairs if you saw how it was installed and operating. It was horizontally vented with dryer vent... He also had a 95% efficient 90k btu lp forced air in the office attic, and another 90k lp forced air in the attic of the upstairs with an ac unit attached and a coal stove in the basement. He took the forced air/ac and coal stove when he left. It was pretty obvious he never got the radiant heat working right.

I saw the death trap draft furnace and I had only 3 days to get the house heated for appraisal. I had 3 estimates and then I had them replace it with an exact model, except it was induced draft. The contractors all agreed it would heat the house without any trouble and it does. It was obvious the old boiler plumbing was not correct at the boiler, but I didn't have time to rip it out and start over, the new mini was slid in, converted to lp,inspected for gas leaks, filled and fired the night before appraisal. Its always worked really well despite the wonky pump flow.

I really appreciate all of this help. It seems I most certainly came to the correct place. I have identified several problems and appreciate all the feedback.

According to the Taco manual, this puts me in the 0011 pump selection category.

=======================================================================================================


Please understand that by plumbing the boilers in series it will not hurt
anything or reduce the amount of hot water available to you for showers or heating.

Lots of wood and coal and fossil fuel boilers are piped in series and there is nothing
wrong with that in any way so do not assume anything is wrong or bad about having
boilers plumbed in series.

The plumbing of boilers in series is the easiest, fastest and simplest way to install a heating system as you can install two sets of valves and controls to allow you to have one set of controls for both boilers allowing you to have the natural gas boiler for an automatic back up boiler only and still be able to use itshot water to heat the hot water for an internal domestic hot water coil in the the gas burner or by installing an external domestic hot water coil eliminating the rats nest of plumbing you have now.

The use of a steel expansion tank and airtrol valve eliminates the huge piping needed for
an air scoop as well and you never have to worry about having a bladder expansion tank
to deal with or having the bladder fail and become waterloggged.


Even the smallest natural gas boiler with an internal domestic coil will give you endless
hot water my friend I have 5 GPM coil in mine and I do not run out of hot water and the old coil in the old boilersupplied 5 GPM for 33 years before I had the old boilers changed out due to thier age.

 

[92rslt1]

=======================================================================================================


Please understand that by plumbing the boilers in series will not hurt
anything or reduce the amount of hot water available to you for showers or heating.

Lots of wood and coal and fossil fuel boilers are piped in series and there is nothing
wrong with that in any way so do not assume anything is wrong or bad about having
boilers plumbed in series.

The plumbing of boilers in series is the easiest, fastest and simplest way to install a heating system..
as you can install two sets of valves and controls to allow you to have one set of controls for both boilers
allowing you to have the natural gas boiler for an autromatic back up boiler only and still be able to use its
hot water to heat the hot water for an internal domestic hot water coil in the the gas burner or by installing an external domestic
hot water coil eliminating the rats nest of plumbing you have now.

The use of a steel expansion tank and airtrol valve eliminates the huge piping needed for
an air scoop as well and you never have to worry about having a bladder expansion tank
to deal with or having the bladder fail and waterlog.


Even the smallest natural gas boiler with an internal domestic coil will give you endless
hot water my friend I have 5 GPM coil in mine and I do not run out of hot water and the old coil in the old boiler
supplied 5 GPM for 33 years before I had the old boilers changed out due to thier age.

So your saying run the hot water in series with the indoor boiler and use a single exchanger to heat the indoor boiler?
Or you mean direct connect with the OWB and depressurization of the indoor boiler?
I can't direct connect because all the water from my second story would run out the top of my outdoor boiler.

 

[maple1]

=======================================================================================================


Please understand that by plumbing the boilers in series will not hurt
anything or reduce the amount of hot water available to you for showers or heating.

Lots of wood and coal and fossil fuel boilers are piped in series and there is nothing
wrong with that in any way so do not assume anything is wrong or bad about having
boilers plumbed in series.

The plumbing of boilers in series is the easiest, fastest and simplest way to install a heating system..
as you can install two sets of valves and controls to allow you to have one set of controls for both boilers
allowing you to have the natural gas boiler for an autromatic back up boiler only and still be able to use its
hot water to heat the hot water for an internal domestic hot water coil in the the gas burner or by installing an external domestic
hot water coil eliminating the rats nest of plumbing you have now.

The use of a steel expansion tank and airtrol valve eliminates the huge piping needed for
an air scoop as well and you never have to worry about having a bladder expansion tank
to deal with or having the bladder fail and waterlog.


Even the smallest natural gas boiler with an internal domestic coil will give you endless
hot water my friend I have 5 GPM coil in mine and I do not run out of hot water and the old coil in the old boiler
supplied 5 GPM for 33 years before I had the old boilers changed out due to thier age.

Was your old boiler an open unpressurized boiler?

 

[leon]

So your saying run the hot water in series with the indoor boiler and use a single exchanger to heat the indoor boiler?
Or you mean direct connect with the OWB and depressurization of the indoor boiler?
I can't direct connect because all the water from my second story would run out the top of my outdoor boiler.

========================================================================================================

With your plumbing I see no other option than an insulated storage tank or tanks on a separate loop to the OWB
in the basement.

Then having a second circulator to move the water from the tank or tanks to the sump of the NG boiler and back to the storage tank from a
common tapping not interfering with the second circulator that is pumping away to the heating load.

If you have a large enough header pipe off the top tapping of the new natural gas boiler you can run two circulators.
This is what I did for years having one circulator to balance the temperatures between the two boilers and the
second circulator for the single heating loop in the home.

You can heat all your domestic hot water with an internal Domestic Hot Water Coil in a gas boiler as standard equipment.

 

[hondaracer2oo4]

I don't think he was suggesting unpressurizing the system. CB tells you to just plumb them in series because it's EASY. But that doesn't mean it's the best way to do things. As far as cb not telling you that 1 inch pex only carries 75k efficiently, well it's easy to just sell you one product and tell you it's fine, which covers 90 percent of installs. Rehau and upnor sell 1 1/4 insulated pex and there 1 inch is close to 1 inch id instead of thermopex which is around .8 id. Get a Nrf 36 or 26-99 pump and you will be good.

 

[hondaracer2oo4]

As Leon suggested that is a good option for you but it requires a bunch more expense and time. I think you are going to solve your issue with the correctly sized pump.

 

[maple1]

As Leon suggested that is a good option for you but it requires a bunch more expense and time. I think you are going to solve your issue with the correctly sized pump.

This. And maybe (likely) also pulling out that first 10 plate HX. Storage will usually help any situation, but it's hardly a 'no other option' thing here.

Seems most OWB sellers think it's not a big deal to put in an oversized pump to compensate for undersized piping, if you have to. They don't seem to take into account the flow velocities that can create - or the extra electricity it will consume. And bigger cost of a bigger pump. The 00r is pretty small to start with.

On the DHW heating - not sure it's an option right now, but maybe something to think about going ahead. If you had a bigger DHW tank, you should be able to make all the hot water you can use with a sidearm HX as long as it's getting hot boiler water. It won't make it as fast as you can use it at times, but having a reserve is key with them, and they can charge up a tank fully while you're sleeping. I have an 80 gallon, never an issue having enough hot water even if the boiler goes cold for a day or two. Also, proper orientation of the sidearm with respect to tank ins & outs is key to how good they work.

 

[92rslt1]

I don't think he was suggesting unpressurizing the system. CB tells you to just plumb them in series because it's EASY. But that doesn't mean it's the best way to do things. As far as cb not telling you that 1 inch pex only carries 75k efficiently, well it's easy to just sell you one product and tell you it's fine, which covers 90 percent of installs. Rehau and upnor sell 1 1/4 insulated pex and there 1 inch is close to 1 inch id instead of thermopex which is around .8 id. Get a Nrf 36 or 26-99 pump and you will be good.

I just ordered a NRF 36

I calculated the total electrical increase to be about 15$ a month.
When it comes in I will report back and let everyone know how it works.

 

[hondaracer2oo4]

I ran a NRF 36 for 4 years, never had an issue with it. The pump is BIG, it will still fit in the 00R opening though. The nice thing about the 3 speed is that you can knock it down to a lower speed(less energy consumed) if you don't need to run it full speed. I wouldn't change anything about your system until you get the pump on and find out what you are getting for temp drops across the HXs again when all the pumps are running. Did you remeasure your MC yet in your firewood?

 

[Gene C]

Just an observation, but it appears from your photos that the sidearm is piped wrong. I think the "hot" water coming from the OWB is supposed to go into the top fittings and out the bottom. Just opposite what you have. When working properly the sidearm will bring the DHW tank up to a temp of 180 degrees and will actually require you to install a blending valve to reduce the tank's output temp to 130 degrees so that no one gets burnt. You should be able to remove the small heat exchanger entirely. You may want to consider changing your piping so that the sidearm is actually after the large heat exchanger and only receiving water at 150 degrees and you could eliminate having to install a blending valve. (Still extremely hot but manageable)

 

[hondaracer2oo4]

Great catch, I missed that on the sidearm. Needs the hot water to come in through the top and exit out through the bottom. You want counter flow just like on your flat plate hx.

 

[92rslt1]

CB recommends the hotter water entering the bottom of the side arm exchanger to first heat the colder water and cause it to rise creating the thermo syphon.

There's a mixing valve on the water heater and it does reach about 180.
Without the ten plate though my freezing cold well water and long showers my kids take will quickly use up the hot water. If the pump works ok I will probably leave the ten plate, if I still am not getting good flow I will remove it and go from there.

I have a 30 plate sitting here not being used, it's kinda over kill but it flows over 40gpm and could replace the ten plate if needed.

 

[hondaracer2oo4]

I don't know why CB has decided to suggest this for the installation of a sidearm but the overwhelming opinion about sidearms is that you want the hot water from the owb to enter the top of the sidearm and flow out of the bottom of the sidearm. The way that CB shows it would mean that the colder water is at the top of the sidearm when it exits reducing the amount of thermosiphon pulling action. If the water heater water is increasing in temp as it rises through the sidearm then it will have the strongest pull. Have you re checked your MC in your firewood yet?

 

[92rslt1]

Hoping to check the mc a little later today. I will let ya know what I find.

 

[92rslt1]

Hoping to check the mc a little later today. I will let ya know what I find.

Ok, so no MC test, I accidentally left the meter in the back door of the wood boiler where I leave the cleaning tools and other related items and it got ruined. While I was at it I opened it to clean the solenoids and discovered the primary air flow solenoid was stuck open. Who knows for how long. I usually clean them and lubricate them every few weeks. Doesn't look dirty, I lubed it up and its still not closing after it opens, so I ordered a new one of those as well and a new WC meter. Going into next year I'm getting spare everything. My automatic boiler lights shorted out too and no longer work so I'm doing pretty good lately.

 

[92rslt1]

Ok, Well pump is installed as of tonight. Now to wait a bit and check the results. I set it to level 2.

Also, replaced the bad solenoid and tested some of the wood.
My oak is averaging 20-25. The ash I just pulled out yesterday is at 22 after just cutting it. I'm going to test more tomorrow. The oak was the greener of what I had. I pulled 2 cords of ash just Sunday and I cant wait to let it season a year and test it. Amazing how fast it dries. I'm going to get another 12 cords or so this summer.

 

[maple1]

You're re-splitting the wood & testing on the fresh split face?

 

[92rslt1]

You're re-splitting the wood & testing on the fresh split face?

yea, thats why I was really surprised to see the ash was 22 after I split it. Its been down in the woods for a while, was told 3 years, but doubt it, it looked fresher than 3 years but who knows, doesn't age much until split. Im going to test more tomorrow and see what the average is. I ran out of day light to get into it really deep.

 

[bpirger]

nothing worse than reading an entire thread, having the bigger pump installed, but no followup? how is it working/was it working when cold out?

 

[92rslt1]

nothing worse than reading an entire thread, having the bigger pump installed, but no followup? how is it working/was it working when cold out?

Sorry about that.

I haven't gotten any extreme prolonged cold snaps.

I can say, the pump made a huge difference. I haven't had a day since I installed it that my house was cold, it's been much warner compared to before.

The baseboards actually "tic" from the increase in temp exchange and the pump on the indoor boiler no longer runs non stop.

Unfortunately I won't know if it handles the extremes until next season, but I have every reason to believe that it will be ok now.

 

[bpirger]

Thanks! You have to get the heat to the right place....sounds like you will be in much better shape. Now just get all the wood in. If you don't have next winters in already, try and get lots of ash split and stacked first....it does dry pretty quick. Good luck!

 

[92rslt1]

Thanks! You have to get the heat to the right place....sounds like you will be in much better shape. Now just get all the wood in. If you don't have next winters in already, try and get lots of ash split and stacked first....it does dry pretty quick. Good luck!

Thanks for the insight. That's exactly my plan. The emerald ash borer destroyed a massive local plot of land that I have access too. I want to get at least 10 cord of ash split for this fall and ten cord of oak for next. So far I have 3 cord of 4 year down oak. I'm ready to start splitting and drying for 2017, I am pulling about a cord a weekend.

I know popular doesn't burn well, but I have found it dries fast and on nice 50* days it works great for spring burns and I have about 8 acres of that to thin out too. I hate wasting wood, so even if it's smaller, I am stacking it to dry.

When this boiler has dry wood it's amazing how good it works.