# Aquastat?



## Moose (Jan 6, 2008)

I'm installing a wood/coal boiler/radiant heater picture of firebox attached.  Now my plan is to use the oil boiler only as a distribution vessel and turn the burner off entirley.  I plan to do this by taking the cold water return off the oil boiler and attaching it to the cold water return on the wood boiler.  Then taking the hot water output from the wood boiler and attaching it to the cold water return on the oil boiler.  Then pretty much leaving the rest of the system alone.  The rest of system consists of a DHW heater 2 infloor radiant heat zones and a forced air system with a radiator type heat exchanger.  I intend to totally enclose the boiler in it own insulated room and run the cold air return from the forced air system to blow cold air onto the heater and then run the hot air into the forced air system.

So thats the general plan, but I'm not real familiar with aquastats.  As I understand they turn the pump on at a set temp and turn the pump off at a set temp.  Easy enough.

1.  Can an aquastat control more than one pump at the same time.  like all four zones as I described above?

2.  Can you have an aquastan an a thermostat on the same pump?

3.  Is there anything special I need to do to install an aquastat, if I buy an aquastat will it come with everything that I need to install it?

Think that enough for starter, but I have many more question to follow about actual setup and design.


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## Eric Johnson (Jan 6, 2008)

I'm not clear on what you mean by disconnecting the piping on the oil boiler. What I would do is tee into each line and then circulate hot water from the top of the wood boiler into the top of the oil boiler vessel. You can do that with a Taco 007 or some other small circulator.

An aquastat is just a switch, so you wire it up like one. To answer your questions specifically:

1.) One aquastat will control anything that is on that circuit, including more than one pump, zone valves, blowers, etc.
2.) I'm pretty sure you can control a pump with both an aquastat and a thermostat, though if the thermostat is 24 volts, which most are, you might have to work around that.
3.) Most aquastats have probes that go into a brass well that screws into 1/2- or 3/4-inch tapping on the boiler. So you need a compatible well. You can also get surface-mount aquastats that strap onto a pipe, but they need flow to work.

A few more considerations:

Aquastats come in three basic flavors. You've got aquastats that make the connection on temp rise ("make on rise" or "close on rise") and aquastats that break the connection on temp rise ("break on rise" or "open on rise") depending on what you're trying to do. Those are both called SPST switched aquastats. They also make aquastats with "SPDT" switching, which will go either way. Those are the ones I like, because they can be used in either application, and can even be used to do two different things at once, depending on how you wire them up.

Aquastats allow you to set the differential, i.e., the amount that the temp is allowed to rise or fall from the setpoint before doing their thing again. For example, if you have a pump set up to turn on at 140 degrees, you can set the differential to allow the temp to get down to 120 before it kicks off. Or 130. On a Honeywell, it's a little white dial with black numbers on it underneath the terminals. 

If you know what you are looking for, you can buy new aquastats on Ebay for a lot less than you will pay retail. Like $20 vs. $70. But make sure you know exactly what you're bidding on, because there are a lot of different kinds of stats, and you could easily wind up with one that doesn't fit your needs. Your best bet is to go to the Honeywell website and look up the part number and read the specs. And you have to watch the auctions, because they come and go.


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## Moose (Jan 6, 2008)

I see what your saying with the tee's on both ends this way I can circulat between just the two boilers.  

1.  Do you think that I should just leave the pump on at all times or put it on a stat to turn on only when the temp rises to say 100 or so?  

2.  Why would I want the hot water going into the top of the oil boiler and not the bottom where the colder water would reside?

3.  At what temp would you recommend I set the stat to to turn on all the pumps for the 4 zone to keep the system from over heating. I think the oil burner is set for about 175 right now should I try to keep it in that general temp zone,  and at what point would the temp be in a dangerous level?

sorry if some of my questions seem elementry, but this is truly uncharted territory for me.


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## wdc1160 (Jan 6, 2008)

> I plan to do this by taking the cold water return off the oil boiler and attaching it to the cold water return on the wood boiler.  Then taking the hot water output from the wood boiler and attaching it to the cold water return on the oil boiler.  Then pretty much leaving the rest of the system alone.


I think this is all standard stuff.  Almost everyone here probably has a similar setup.
As far as this forced air business you have some explaining to do.  Also, I was going to try and answer questions about the stats, but 
maybe you should explain more??

Like why aren 't you going to use a hot water to air HX.

Why do you need all these aquastats


One key that Eric points out is 


> Aquastats come in three basic flavors. You’ve got aquastats that make the connection on temp rise ("make on rise” or “close on rise") and aquastats that break the connection on temp rise ("break on rise” or “open on rise") depending on what you’re trying to do.



All of this has to do with differences in water temp.  I don't know why you would work these into individual zones or to control the the circs or pumps.


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## Eric Johnson (Jan 6, 2008)

Those are perfectly good questions, Moose. All of us have wondered about them at one time or another.

You want to maintain a certain temp range in your wood boiler for better efficiency, since a cooler boiler doesn't burn the fuel as well. Therefore, you'd want an aquastat to shut the circulator off below a certain temp, say 150 or 160. On startup it will cycle on and off until the boiler gets up to temp, and then run continuously through the end of the burn cycle. You'd mount that stat on a well in the boiler, if possible, for the most accurate readings. You could wire the circulator to run all the time, but you'll have a more responsive system if you control it.

If you pipe the hot water from the wood boiler into the top of the oil boiler vessel, then the hottest water is immediately available to the zones. When you're trying to heat your house, you really don't care what the temp at the bottom of the boiler is, since you draw your water from the top. Makes sense when you think about it but most people, including me, tend to automatically assume that you should pump the hottest water into the return, in order to heat the whole boiler up evenly. But as I said, why?

A typical overheat trigger temp would be 200 degrees. You'll probably have the best results from your system if the boiler water temps are in the 180-190 degree range. But with an aquastat, you can play around with it and see what works best.


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## Moose (Jan 6, 2008)

Ok lets start with the pumps and stats.  I want to use one circ pump to feed the oil boiler to ensure thet the oil boiler temp is kept up to temp.  As of now all of the zones currently draw off of the oil boiler and I don't see any reason to change this at this point.  So rather than just keep the circ pump between the two running all of the time I thought I could control it with a stat to turn it on only when it needed to run.  As far as the other stat I was thinking I could hook it up to the other heating zones to turn the pumps on when system started to over heat to keep it from doing so this way even if the zones wern't going to call for more heat I would force the heat there just to dump it in the event of an overheating situation.  

The forced air side of the system has a radiator that is attached to the boiler and a large fan forces air across the radiator to transfer heat from the water to the air.  its pretty straigt forward I'm just going to reroute the cold air return to run across the fire box to utilize the radiant heat from the wood boiler to move the hot air upstairs.  Hope I'm explaining this alright  please ask for more specifics if I'm not explaining my self clearly.


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## wdc1160 (Jan 6, 2008)

Eric,  if it were one stat he was asking about I could see it. 
 but it seems were dealing with the zones as well?


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## Eric Johnson (Jan 6, 2008)

I understand what he's saying. He needs an aquastat to run the circulator to get heat into the oil boiler pressure vessel, and he wants another one to turn on his zone pumps in case the boiler starts to overheat. They would both be "make on rise" versions, just set to different set points, i.e., 160 and 200, or something close to that.

The boiler shouldn't overheat, BTW, if it's working properly. Most wood boilers just shut off the air supply when they hit the setpoint (say, 190) and that pretty much stops the heat from climbing. You get into overheating problems when a pump fails, for example, and the boiler can't dissipate any heat. So it's a good idea to do what you are suggesting, but it's not going to help you in a power outage. It's a good idea to have a gravity heat dump for those occasions.


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## Moose (Jan 6, 2008)

ABGWD4U said:
			
		

> Eric,  if it were one stat he was asking about I could see it.
> but it seems were dealing with the zones as well?



Lets break it down into two sides on side it going to be the circulation bewteen the two boilers with a stat to controll it.  I want to use a pump rather than gravity.  I want to put a stat on this side to keep the pump from running continuously.

The other side has four pumps for four different zones 

zone 1:  radiant floor heat 1st floor
zone 2: radiant floor heat 2nd floor
zone 3: DHW
zone 4: radiator for for forced air system.

I want to put the stat in for this side to use all four zones as a dump zone to keep from overheating.  May not use the DHW as a dump zone.  I don't want to controll the water with the fire and danpering the fire.  I would rather try to find a what kind of fire I need to substain the system with out danmpering and use the dump zones as a safty if I over fire.  I maybe way off base but like I said before this Is all new to me.  I've always had your standard wood stoves.


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## Moose (Jan 6, 2008)

I'm looking into power outage options  and I plan to have the boiler danmper down if the pumps fail to do their job,  but I would much rather have a slightly warmer house than have a smoldering fire if at all possible.


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## Moose (Jan 6, 2008)

Pic is upside down hovent gotten arround to fixing it yet.....


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## Eric Johnson (Jan 6, 2008)

You would need two make-on-rise aquastats, two wells and the usual wiring gear to set it up like that. Presumably the four zone pumps are on the same circuit. I'm not much of an electrician, but I would wire a hot lead through the aquastat and then run wires off the other terminal to each of the pumps. Set the aquastat to 200 and when it hits that temp, the juice will flow to the pumps. The other one also goes into the top of the boiler and the circulating pump is wired through it. I'd set it at 160 with a 20-degree differential and see how it works.

I don't understand your strategy for controlling the fire at all. Does your boiler have a draft induction blower or is it a flapper that opens and closes as the boiler heats up and cools? Or something else? You can exert some control over the fire with a standard stovepipe damper, which I would recommend installing in any event. But there needs to be some automatic way to control the combustion air. Letting it overheat and then trying to dump the excess heat is a very bad idea. If you can't automatically control the boiler, then don't try to operate it.

Why don't you post a pic of the whole thing, instead of just the firebox? I'd like to see what we're talking about, here. As I recall, it's more of a hybrid than a conventional wood-fired boiler. It may require a different piping and operating strategy than what we've been talking about.


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## Moose (Jan 6, 2008)

front with automatic danmpner and side pic


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## Moose (Jan 6, 2008)

back with plumbing


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## Moose (Jan 6, 2008)

Letting it overheat and then trying to dump the excess heat is a very bad idea. If you can't automatically control the boiler, then don't try to operate it.

I guess I'm not intentially trying to overheat it.  It is still going to have a way to control the fire.  I am going to attempt to to keep it from over heating with the size of fire that make, but honestly I have no Idea how this thing is going to react  so I think I just need to get it installed and see what I have.


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## wdc1160 (Jan 6, 2008)

Why no HX?


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## Moose (Jan 6, 2008)

Not sure what you mean please enlighten me..


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## wdc1160 (Jan 6, 2008)

Moose you have a unique thing your doing.

Forget all about the pipe, aquastats and  zones.

Your turning a old oil boiler into a HX = Heat Exchanger.

Water to air HX.

Many folks have made homemade HX's, but I am sure this must be a first right.

Why isn't the boiler just sold, or thrown out to replace it with a store bought / more conventional homemade approach.

I am not judging, I just don't understand how it came to this.  It is probably important.


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## Moose (Jan 6, 2008)

Well I guess in my mind I'm not using my oil boiler as a heat exchanger as much as I am trying to us it as a heat distribution center.  The boiler works fine and I used it up until last week to heat my DHW until I ran out of fuel.  I suppose I could just go buy some more oil at  3+ dollars a gallon but I've never heated with anything other than wood my whole life even when oil was less than 50 cents a gallon.  Eric made a good point in another thread that if I were to take out the boiler or take over its chimney then if I ever had to leave the house for any amount of time in the winter I would have no way to heat the house.  I don't know who it was, but some one mentioned that either my insurance or my mortgage company might not think to highly of me removing the conventional heat source.  and if I ever wanted to sell the house I would be drastically reducing the number of potential buyers by not having a convential heat source.  Plus everything is already there installed and in working order all I intend to do is change the way I heat the water.  Heat with wood rather than oil.  I suppose If I wanted to spend the extra money I could go buy a traditional add on boiler or just go buy a combination wood/oil boiler, but I dont' think that it would be a cost effictive option for me at this time especiall when I got 2 stories if chimney and the boiler for less than It cost me to instal a chimney in my last house.  I don't suppose that what I am doing or what I want to do is the best or most efficient but I have to work with what I have.  I am definatly open to Ideas I you think there is a better more cost effective or safer way to do it please let me know because as I have stated I am pretty new to the whole heating water thing.


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## wdc1160 (Jan 6, 2008)

> Well I guess in my mind I’m not using my oil boiler as a heat exchanger as much as I am trying to us it as a heat distribution center.



Aren't you getting the heat from the boiler to heat air through ducting/sealed room
Was it designed orginally to do that?

I know this has to be frustrating.  You have got 10 separate issues in one setup.



> Eric made a good point in another thread that if I were to take out the boiler or take over its chimney then if I ever had to leave the house for any amount of time in the winter I would have no way to heat the house.  I don’t know who it was, but some one mentioned that either my insurance or my mortgage company might not think to highly of me removing the conventional heat source.  and if I ever wanted to sell the house I would be drastically reducing the number of potential buyers by not having a convential heat source.



Taking out the orignal boiler would be reality suicide.  Not everone is a wood burner.  You not gonna changem so don't try by removing their furnce.  

I thought you meant that it was broken down, not wanted, or unfixable.  So it is in working order, but your not actually going to be using it for anything except shipping heat to various places.

Why is it advantagous to use this boiler and sealed room as a "heat distribution center"  <- (In indiana this is a police station)


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## Moose (Jan 6, 2008)

ABGWD4U said:
			
		

> > Well I guess in my mind I’m not using my oil boiler as a heat exchanger as much as I am trying to us it as a heat distribution center.
> 
> 
> 
> ...



I do have a heat exchanger where the hot boiler water is circulated through a radiator looks like what you would find in an air conditioner or car with a fan that blows air from the cold air return across the radiator wich picks up heat from the radiator and the air is then pushed into the house...  I don't know if boilers were ever really designed to do this but the  unit with the radiator in is was.  it looks just like a furnace with no heating eliment other than the radiator that is heated by the boiler on the other side of the room.  I'll take pics tomorrow maybe this will help.





> Why is it advantagous to use this boiler and sealed room as a "heat distribution center"  <- (In indiana this is a police station))




I'm not sure what your asking here I guess I'm falling back on if it ain't broke dont' fix it.  the thing works I just want to use another fuel to heat it.   If your refering to the sealed room I was talking about ealier I was going to enclose the wood boiler because not all of the heat is going to be transfered to the water and at least half of the btu's will be radiant.  by enclosing the wood boiler I am going to attempt to get the most warm air as I can upstairs and out of the basement before the cold stone walls have a chance to absorb the heat.


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## Eric Johnson (Jan 6, 2008)

How is the air to the wood burner controlled?

BTW, I don't think you're doing anything very exotic or unusual. It seems logical to me. I'm just confused about the nature of the beast you're going to be using. It sounds like this is more of a wood stove with some water piping, in the sense that the air controls are set manually, like a stove. So in that case, you really wouldn't be able to control it like a conventional boiler, and perhaps your heat dump idea makes sense. Or maybe there's some relatively easy modification that would make it work better. 

The nice thing about projects like these is that much of your work goes into piping and controls that can easily be adapted to another boiler, if you decide to upgrade in the future, which you would probably want to consider doing anyway. There are plenty of good used wood boilers around for pretty cheap if you want to do the heavy lifting. I picked up my previous boiler, which kept us warm for 4 seasons, on Ebay for less than $300. I put another $3,000 into the piping, etc. Made it a lot easier to upgrade to the gasifier.

"Heat distribution center." I like that, Bill. Around here it's called Dunkin Donuts.

What EKO model are you getting?


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## Bartman (Jan 6, 2008)

Hey guys, just saw this post.
Moose, it sounds like you are trying to install what I have here, except for the water/air heat exchanger. My system has 5 zones, 1 DHW, 2 radiant, 2 hydronic baseboard. Personally I feel that you should keep the oil burner in place, it's not hurting anything to keep it there. I am a fan of redundancy, only for the simple fact, if something can go wrong, it probably will. What will happen if for some reason the wood boiler goes down, you're screwed, or you're running on wood and it's cold out and all of a sudden you have to get to the hospital (hypothetical), the wood goes out, you have no heat. With the oil burner, wood goes out burner kicks in, you're covered. After reading the posts I drew a quick sketch of my plumbing of the 2 boilers, I also took some pictures to maybe help in illustrating how I did it. My system uses 3 aquastats, 1 triple action, 2 spst. On the wood boiler, the aquastat on the left controls the combustion air blower, opens @ 165F, the aquastat on the right is the overheat aquastat and closes to energize the 4 pole overheat relay to overide all 4 heating zone thermostats, that closes @ 190F. My oil boiler has control of the system, but wood boiler has priority, unless outside temps dip below 20F, then both burners have priority. Currently I'm looking into changing the way the system works a bit to make the boiler really idle, then really burn.

Right now I'm having a little trouble reducing the pixel size of my drawing, so bear with me.


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## Moose (Jan 6, 2008)

Eric, you are correct in saying that what I have is a wood stove with coils in it  and it has no induction fan. I just use the term boiler lightly for simplicity sake.  as far as induction air as far as I know there is a bi-metalic coil in the door which helps control the induction air automatically.  I will install a dampner in the black pipe and control that manually as well.  I would love nothing more than to get a nice gasification boiler but having two mortgages right now has that on hold.  So this is what I have right now and I feel pretty confident that I will be able to heat my house better that what I am doing now.  I will post some pictures of the current set up with the oil boiler and the water/air heat exchangers and I think this will clarify some things.


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## Bartman (Jan 6, 2008)

Here's the schematic, pardon the lousy drawing. When running in non-wood mode, valves 1 & 3 are closed, valve 2 open. In wood mode, valves 1 & 3 open, valve 2 closed.


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## Bartman (Jan 6, 2008)

Here's what my control looks like, and hopefully the aquastat pics can fit too.


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## Moose (Jan 6, 2008)

are the 5 circles in the center of the drawing the return lines???


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## Bartman (Jan 6, 2008)

Here's the actual piping. Valves 1 & 2 are to the left, valve 3 is on the right.


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## Moose (Jan 6, 2008)

Ok i get it, just took me a minute


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## Moose (Jan 6, 2008)

I see you have an expansion tank on both untits, should I do the same?  Is bigger better?


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## Bartman (Jan 6, 2008)

Yeah those little circles have "Cs" in them for circulator. When I re-piped the system this fall, I eliminated flowchecks, and used the new Grundfos circulators with built-in check valves, I also eliminated the copper lines running to the boiler and used PEX.


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## jebatty (Jan 6, 2008)

A lot has happened since I started to write this, so much of this might no longer help.

This is a hard one to follow, but for what it's worth. First, I am not a professional, just a home experimenter, offering advice based solely on my experience. I always consult pros (and pay for the advice) if danger to me, others, or property may be present. That is true, here, so, Moose, take the benefit of my experience for what it's worth but rely on my experience solely at your risk.

It seems to me that Moose wants to retain an operable oil burning boiler but add a new wood burning boiler which will be the primary heat source, with a fall back to oil if needed or wanted. So, this probably should be a parallel hook-up with the hot output of the WB going to a T on the cold return of the OB. The other port on the T is the cold return from the heating zones. The hot output of the OB also should be a T, with one port going to the cold return on the WB and the other port to the heating zones. For Moose's purposes, the aquastat on the OB either is disabled or set high so that it will not fire the OB so long as the WB is supplying all needed heat. If disabled, it would need to be reconnected when the oil burner is placed back in service.

The aquastat on the WB is set as normal, often on at 160 (make on rise). This aquastat will turn on a circulating pump on the WB to circulate hot water in a loop through the OB. If system water temp falls below the differential point on this aquastat, the circulating pump will turn off. This would happen as the fire in the WB goes out or heat demand depletes the system. This aquastat could be one that clamps onto the hot water out on the WB (but another issue here discussed below).

Draft/fire control on the WB is a different issue. I don't have an immediate suggestion here, but on my boiler I manually turn on the draft fan when I fire the boiler, the fan operates until boiler water temp reaches 190, then the fan shuts off; fan comes back on at about 180, and this cycle continues until the wood burns out. When boiler water temp falls to 140 the draft fan shuts off, the assumption being that the fire has burned out. The control to do this was part of my boiler's control panel.

The heating zones operate off the OB loop. Assuming one heating zone, this zone could operate with a line voltage thermostat which turns on a separate heating zone circulating pump. This pump draws from the T on heat out of the OB and returns to the T on cold return of the OB. A similar arrangement can handle multiple zones with zone valves (and perhaps balancing valves). 

The WB also should have an overheat loop in which to dump excess heat. I suggest a separate aquastat that fits into a well in the WB and is wired in parallel with the regular WB aquastat as well as operating a relay in parallel with the zone thermostat to turn on the heating zone circulating pump. The overheat aquastat might be set at 200 (make on rise). If the overheat temp is reached, both pumps start to allow heat dissipation. This works until there is a power failure and the WB is in full burn. Although the draft fan will go out, temps still can rise. and I suggest a separate gravity fed dump loop directly off the hot water out of the WB. To keep this from operating all the time, I suggest a normally open solenoid valve on this line. In other words, so long as power is available, this valve is closed and the overheat loop does not function. On power failure, this valve opens and the gravity fed overheat loop operates. Sizing of this loop I understand should be at least 15% of the BTU output of the wood boiler.

Now, the other issue mentioned above as to the WB. For this boiler to operate efficiently its water should be kept hot and cold water should not be fed into the cold return, except when the boiler is first heating up. This requires a thermostatic mixing valve on the hot water out of the WB. All hot water on initial firing (actually, not very hot), is returned directly to the cold water return of the WB. As the water heats, this valve gradually closes and hot water is diverted to the hot supply line for the heat zones. Return water then also goes through this valve, and the valve mixes hot water directly from the boiler with the cold return water so that warm to hot water always is returning to the boiler, resulting in high boiler efficiency.

On my boiler I have a surface aquastat on the return line to the boiler AFTER the thermostatic mixing valve. This is the aquastat mentioned in the second paragraph above. I set this to come on at 150. The return line to this point is operating on gravity, hot water out, through the mixing valve, and right back into the cold return. Because of this gravity feed, the aquastat comes on quite quickly, turning on the WB circulating pump. But as stated, initially all of the output of the boiler is fed right back into the boiler by the mixing valve until the boiler fully heats, then the mixing valve starts to close, diverting hot water into the heat zones. As the whole system comes up to temp, the mixing valve closes more and more, until potentially diverting all output into the heat zone.

Hope this helps. You have quite a project on your hands.


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## Bartman (Jan 6, 2008)

Yes, I actually have 3, I have 1 on the DHW also. Originally I had to big ones, now I have a big one on the wood boiler and a small one on the oil boiler.


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## Bartman (Jan 6, 2008)

Jim's got a handle on the how the system should work, and his description is damn near the same as my system, except that my control system is a little more complex and is only going to get worse. The only thing I don't agree with is a parallel system, but that's a matter of choice. A series system narrows the control of water temps throughout the system, and I'm not for shutting down any electrical controls, all controls should be intergrated with safeties in place. Back when I designed my system, nobody had wood or alternate heat, I was on my own, and it took me 2 weeks to design it going back and forth adding possible scenarios. Back then I was 29 and pretty sharp, now I'm 50+ and pretty dull. In all the years I've had this up and running, I have never had one bit of trouble with the control, only circulators, oil pumps, and burners. It's fun to see other's with the same interests and similar and different ideas.


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## Bartman (Jan 7, 2008)

Here's my power failure zone valves. Originally they were mounted on the boilers, and wired in metal flex conduit. Now they are mounted to the PEX and "float".


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## Eric Johnson (Jan 7, 2008)

Why do you recommend putting the hot supply from the WB into the return of the OB, jebatty?

He doesn't have what could really be classified as a boiler. I think it's more of a wood furnace/stove with some pipes running through the firebox. As such, probably no place to insert aquastat probes. The bimetal draft control sounds like it might work alright, though. The normally closed zone valve I have is called an Automag. It opens up when the power supply is cut.

Instead of a mixing valve, I have a Taco 007 pumping supply water into my return at low boiler temps. It's wired to the controller.


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## Bartman (Jan 7, 2008)

What size are the fittings on the boiler/furnace Moose? Forgot to ask that one, if the "hubs" are small (3/4") the boiler should go in parallel, if they are large (1 1/4"-1 1/2") it should go in series. 
Eric,
 If you put the boilers in series all of the hot water goes through the oil boiler and will satisfy the aquastat, if you run in parallel, the oil boiler will never see wood heated water and will try to run independantly. Parallel is fine if you're going to shut down the oil unit, but then you have no automatic backup, (without elaborate control).


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## Moose (Jan 7, 2008)

donno I'll check tomorrow.


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## atlarge54 (Jan 7, 2008)

I would have serious doubts about your stove being big enough to replace your oil boiler. What is the BTU rating of your oil boiler? Comparing pipe size on boiler and stove should be a good indication. My system would be somewhat similar to yours (less the oil boiler) my heat coils are outside the firebox, water circulates constantly, aquastat controls combustion air. I've followed your chimney issues somewhat and I'm a little concerned about chimney pipe going into stone chimney and cooling with cresote build up. How easy will your chimney be to clean frequently? I think I'd try to plumb through the boiler when burning wood (power off and flue blocked on oil unit) then use ball valves to isolate wood stove so oil boiler is left in it's current configuration. I don't want to discourage you in any way, but keep in mind complexity tends to feed on itself. I'll bet you'll have dreams of pipes, wires and pumps tonight. Gook luck Mr. Moose


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## Moose (Jan 7, 2008)

atlarge54 said:
			
		

> I would have serious doubts about your stove being big enough to replace your oil boiler. What is the BTU rating of your oil boiler? Comparing pipe size on boiler and stove should be a good indication. My system would be somewhat similar to yours (less the oil boiler) my heat coils are outside the firebox, water circulates constantly, aquastat controls combustion air. I've followed your chimney issues somewhat and I'm a little concerned about chimney pipe going into stone chimney and cooling with cresote build up. How easy will your chimney be to clean frequently? I think I'd try to plumb through the boiler when burning wood (power off and flue blocked on oil unit) then use ball valves to isolate wood stove so oil boiler is left in it's current configuration. I don't want to discourage you in any way, but keep in mind complexity tends to feed on itself. I'll bet you'll have dreams of pipes, wires and pumps tonight. Gook luck Mr. Moose



Honestly I don't expect the wood burner to out perform the oil boiler, but since I've never used the oil boiler other than DHW I don't think I would ever know.  If I get nothing else out of the wood boiler other than DHW then I would be satisified.  Anything more that that I would consider a bonus.  I know the thing is going to produce heat.  the firebox on that thing is huge so I'm going to put it in and see what happens just want to do it safely and efficiently and I'd rather not have anyone say what the ____ were you thinking : )  I have decided to install an new chimney and just run it straight through the roof I think eric and bartman talked me in to that.  Besides the oil boiler goes through the masonry chimney also.  And to be honest I have dreams of two pipes one to to connect the wood stove/boiler to the existing system, a couple of new aquastats, and one more pump.  trust me I like to "keep it simple stupid" as they would tell me in the Corps.  And I will definatly need all the luck I can get.


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## jebatty (Jan 7, 2008)

Bartman said:
			
		

> The only thing I don't agree with is a parallel system, but that's a matter of choice. A series system narrows the control of water temps throughout the system, and I'm not for shutting down any electrical controls, all controls should be intergrated with safeties in place.





			
				Eric Johnson said:
			
		

> Why do you recommend putting the hot supply from the WB into the return of the OB, jebatty?
> 
> Instead of a mixing valve, I have a Taco 007 pumping supply water into my return at low boiler temps. It's wired to the controller.



If Bartman feels fogged at 50+, then my lights are about to go out 'cause I'm nearing 61 -- and just installed on my own my first wood gassification boiler. What this means is that one doesn't need too many watts firing to see the light or that intelligence is fully failed to allow one to do stupid things.

Why the parallel hookup suggested as I did? My logic tells me the answer lies in an assumption of two operating systems (both can be fully operable with all safety controls intact for each). In Moose's case, leave the OB controls intact but set the "on" aquastat at a temp above the WB aquastat if Moose wants the WB to be the primary heat source or disable it if Moose wants to heat only with WB. The OB aquastat controls firing of the OB and OB circulator. If disabled, the OB never fires, so I don't think there is any OB safety issue. If set higher than WB (maybe a WB 150 - OB 160 setup), then OB fires only if WB is not providing sufficient heat. Because WB hot is feeding OB return, OB is only providing "makeup" heat and will run minimally, such as when demand exceeds supply capacity of WB or WB fire out.

I mentioned the aquastat on my boiler is mounted on the return line AFTER the mixing valve. With this 2 boiler setup, I think it should be mounted directly on the heat supply side of the WB. Then the WB circulator will come on anytime temp reaches its setting, such as when WB is up to heat or WB is down and OB is supplying up to heat. I suppose by using a relay set up the aquastats on both the WB and the OB could turn on both boiler circulators anytime either one reaches the setpoint. This would provide unrestricted flow through the boiler loop whenever either boiler is operating. [this is where the fog sets in -- any pro's have advice? I think water passes through a circulator with little restriction when it is not operating, so maybe both don't have to be on.]

Critiques by others is welcome. Again, good luck on this.


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## Moose (Jan 7, 2008)

Well here are the pics Ive started with the water to air heat exchanger since I think this is the one I"ve had the hardest time explaining....  this is the forced air side of the system.  air is brought from the living space across the radiator heated by boiler water then pushed back into the living space.


outside of water to air heat exchanger...  whole unit with some ducting...







close up of the radiator inside the unit







radiator with blower motor


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## Moose (Jan 7, 2008)

Here is the existing oil boiler (in working order)

return lines with valves








supply lines with taco pumps









pump control hub








in floor radiant heat


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## Moose (Jan 7, 2008)

Only been in the house since sept.  I wouldn't know


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## Moose (Jan 7, 2008)

now my plans are to put a Tee in at the elbow most shown in the pic below and another tee at the elbow just below not shown and place three valves basically the same thing the bartman did (I think) I think it should be simple enough the aqua stat for the over heat dump will be by valve 3.  Seems simple enough to me.


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## Eric Johnson (Jan 7, 2008)

You've got both the supply and return from the WB going into the return of the OB. I don't think that will work. This drawing would work if there was a heat exchanger on the OB's return line, but you're piping direct, which means you need to use both the supply and return on the OB, I think.

Here's a very basic diagram of my piping arrangement. I piped the DHW hx ahead of the gas boiler vessel because I want consistently hot water at the tap. Higher WAF. Also note that I piped the sidearm heat exchanger backwards in the diagram. I always do that, for some reason. Actually, the flow is top to bottom, but you get the idea.


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## Moose (Jan 7, 2008)

I know the drawing is crude,  I did it as I was running out the door, but those thiangles with the apexes together are going to be valves. and valve #1 will be closed with valve 2 & 3 open with the WB in operation and then just the opposite when the WB is not in use.  with the WB in operation the return would feed the return on the WB heat the water then the supply on the WB would feed the return on the OB then the supply on the OB side would not change.  I too would like the DHW first on the route but I think I will leave it like this for the rest of the season and tinker with it in the summer (basements are cool in the summer.)


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## Bartman (Jan 8, 2008)

Hi Moose,
 Your valve 2 has to be on the return side of the wood boiler, valve 3 on the supply of the wood boiler. By the picture it seems reversed, but valving is in correct orientation.

That's a nice looking air handler, I haven't seen one here with the built-in heat exchanger. Usually I buy the heat exchanger separately, then have 2 transitions made by a sheetmetal fabricator. 

I have never seen one of those heat exchangers plug up, doesn't mean it can't happen though. 

That Weil McLain is fairly new, and is a good performing boiler, it just needs a better burner.


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## Moose (Jan 8, 2008)

So I can't just disconnect the return from the OB and connect it to the return on the WB  then connect the supply from the WB and connect it to the return of the OB?


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## Bartman (Jan 9, 2008)

Yes, that's what I do in my system, and that's what the plumbing diagram showed. In your diagram it looked like you had both boiler returns connected together, and the zones coming back into the wood boiler supply. Maybe it was just the way you drew it, usually in a block diagram, the return is always on the bottom of the boiler, supply is on the top.


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## Moose (Jan 9, 2008)

Oh, I didn't draw them in any order.   When I saw your drawing It was basically what I wanted to do I just never thought of the valves to isolate the WB in the event that it was not being used.  I will attempt to incorporate a similar set up.   I think I'm going to start the project this week.  I was able to find the chimney that connected to my pipe it was a selkirk product.  Actually found it at ace hardware.  Got the block and tackle yesterday so that I can lower the beast into the basement.  Hopefully I don't run into any major road bumps....


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## Bartman (Jan 9, 2008)

Moose, I modified your drawing, please excuse the sloppieness, I had to enlarge it and do it in MS Paint.


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## Bartman (Jan 9, 2008)

Hope you have a lot of muscular friends.


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## Bartman (Jan 9, 2008)

One quick question on your Weil McLain. How does the flue pipe run to the chimney? It looks like you have a funky elbow there. For maximum performance, you need to keep the elbows and tees to a minimum.


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