Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: markpallen on February 20, 2017, 08:28:26 AM
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Ive been doing lots of reading , trying to answer my own questions but could sure use some experienced input.
Currently my wood doctor (medium size, 250000 btu, 150 gal ) is serving only my house but I want to add heat to my garage. My set up as it is now : OWF 125 feet from house fed by 1 in. kitek inground. There is a grundfos UP 15-42 at the owf pumping hot water 125 ft into a 20 in x 20 in water to air exchanger in my oil furnace plenum. From there to a 48 in sidearm for dhw and then returns to the boiler thru another 1 in kitek pipe.
My thoughts are this: Id like to add a secondary circuit by adding a pair of Ts at the very end of the return line. I currently have rehau insulated 1in pex buried beside the boiler and running into the building I want to heat. The distance is 20 ft from the boiler to the inside of the building. Once in the building I would take water to the second floor into a Trane water to air unit. My thoughts are to then take the return from the trane to feed my infloor heated slab and from there return to boiler.
I have a 100 gal insulated tank that I can use if the consensus is to keep my boiler water separate from the building water. Perhaps I could just use the new piping from the OWF to heat a sidearm ( or flatplate exchanger) which would then heat the 100 gal tank, and then plumb from the tank in the building to both the infloor and the trane unit upstairs.
I have 2-3 spare grundfos pumps if that factors in.
My current setup as described at first has been running with no issues for 12-13 years. My return temperature to the boiler is only 15-20 degrees colder than the supply, so Im guessing 160-170 degrees. I have not measured this temperature but it feels almost as hot as the supply line beside it.This is what I propose sending to the new secondary circuit.
If you havent realized it yet, I am plumbing challenged but hopefully have explained my setup enough that more knowledgable people can steer me in the right direction.
A couple considerations.... my boiler is nearly level with my furnace plenum in the original primary circuit , only 125 ft away.
Also the slab in the building I want to add heat to is level with the ground the OWB is sitting on. The vertical rise to get water to the trane unit on the second floor is about 16 ft.
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Not familiar with Wood Doctors, for starters if you have the ability to add a second pump at the stove, it would be much better to run your second building on its own circuit instead of adding from the house circuit, if the house is calling for heat and the other building is calling for heat, the return temps could get way too low.
If what you have works then don’t worry about it, but is pretty common practice t run to the sidearm first then the furnace.
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You will want to add another pump. Leave the existing loop alone. If you don't have more ports on the boiler, tee into supply and return. (before pump)
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Ive had no issues with the side arm as it is currently hooked up so I wont likely change it. I have seen that mentioned in past posts and debated doing it .Maybe if I ever upgrade those leaky kitek fittings I will.
There is precious little room in the back of the boiler for another pump. If I can squeeze a T in before the pump for the house, would a pump pull the 20 feet from the boiler to inside the building? Or should I make room for another pump so it can push?
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Sometimes a picture goes a long way.
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I would certainly agree, leave the existing lines as they are and add a second loop to the garage right at the boiler, perhaps a primary loop to the garage and then a secondary loop from it up to the upstairs unit in the garage?
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Okay its making sense to me. What are the thoughts on pulling the water about 20 ft rather than pushing it? Its awfully tight in back of the boiler.
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It can be done as long as the pump is lower than the hookup on the boiler, it’s a LOT easier to bleed the system with the pump at the boiler though. Originally I had my pump in the basement, it was several feet lower than the boiler, was still a pain to get all the air out and get a good prime.
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If water will flow by gravity to the pump then it should be fine.
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Thanks for the input guys. I think maybe I will wait until I shut down the boiler for the summer and then see if I can squeeze another pump in the back of it.
So if I'm understanding correctly, I will TEE off the main inlet and outlet and run a totally separate circuit for the new building.
Any thoughts on whether I should use a separate water tank for heating the new area? I considered heating a 100 gal tank with a sidearm or plate exchanger , and then circulating that water in the building thru the radiant slab and a water to air unit on the second level.
The second building will only see occasional use so heating would be minimal.
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If it is only intermittent use then I would swap out the 15-42 pump with larger pump like a 26-99 and put a plate hx in series with the return in the back of the boiler. Then you can run glycol in the line to the new building so the pump doesn't need to always run and pressurize it so it will feed the upper floor easier. You would need an expansion tank but shouldn't need a storage tank.
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I agree with RSI, the tank isn't needed.
Using flat plate on the house return to separate the garage loop to put glycol in it would be fairly simple if the building has a chance of freezing during a power outage. Otherwise I'd just put two tees in the back of the boiler and pump a continuous loop to the upstairs air handler in the garage. Those tees would ideally pull full temp boiler water but catching house return water could work for intermittent heating. Upsizing the house pump would depend on return temps while house heat is running.
Then you'd have another set of close tees on the return of the garage air handler loop that would allow you to pump the garage floor pulling through a mixing valve. It's low temp so return water is still hot enough.
The only concern I would have is that if the garage is pulling off the house loop your return temp after the garage could at times be pretty low. Might cause a condensation corrosion problem if your furnace is mild steel and the return hits one spot on the firebox. I'm not sure how the return enters your unit. I've never worried about that on the 409 units I've done.
Basically I'm agreeing with RSI and others, just rambling on about options. :)
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Good gawd I may actually be starting to get this figured out. So the plate exchanger will isolate the water in the boiler from the glycol mix to the garage. Even if I don't use glycol this is an option. In the event of a power outage I have to hook up a generator for the house heat anyway because it is only water.
Putting two tees in back of the boiler is definitely easier as I wouldn't have to mess with the pump setup. There is very little room to work back there. So two tees in back of the boiler, on my return from the house. In the garage I would add a second pump to get water to the second level, thru the air handler, then back to the boiler. In the future I can put another pair of tees before it returns to the boiler and using a mixing valve, supply the slab.
I appreciate all the input guys. I was born without anything resembling a plumbing gene.
One of these days I'll mention a second garage with a heated slab that I will be hooking up too....
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There was several different things suggested. Once you decide what will work best, we can give you better suggestions.
If you can get it to work without a plate heat exchanger it will be a simpler system. If you are going to use one anyway, I would do like my last post to keep it a little more simple than if you put it in the new building. You would most likely need to use a larger pump like I mentioned to get enough GPM for the added load.
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I really doubt you'll need a flat plate/pressurized system to push air down only16'. We do attic air handlers quite often and they're more than 20'. Just plumb a way to use your well pump to blow it out the first time. Believe me a garden hose connection can save hours of purging.
And if you tee off the return from the house put a ball valve between the tees to use the house pump to help push the first time. Then leave the valve open.
Keep the pumps low and push rather than pull water.
Are we giving too many options yet ? Chuckle.
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Are we giving too many options yet ? Chuckle.
There is a fine line between enough info to really help, and then a bit more makes mud of clear water. I havent reached the muddy water stage yet. lol
I was going to get this building operating and worry about the second garage in the future but then im thinking I may end up having to change everything to do the second one.
While Im plumbing the building ive been asking about, is there anything I should add or do now to make garage no 2 easier to plumb in the future? It has infloor as well and a second floor too.
Perhaps I should give a list of some things I have in case any of it spurs some ideas.
Grundfos pumps.....two 26-99's , one 15-42 and one 15-58. All were bought " in case" I may need them from classifieds.
Many feet of old style baseboard.
Three cast iron rads of various size
Two new, never used school type radiators with the slanted top
These were mostly bought at very low prices just incase I would need them. I have little money invested in any of it , so if its no use to me its not a huge concern.
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Depends, I mentioned radiators once to the wife and the look I got would freeze hell over, that was mild compared to the look I got when I mentioned how easy it would be to add baseboards to a few upstairs bedrooms.
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That's funny, my wife loves the two cast radiators we have in the basement. They make wonderful clothes dryers.
To give advice on how to plumb for the second outbuilding it would be nice to have an overview on which directions the buildings are from the furnace and distances. My guess is you'll have to make some kind of supply and return manifolds on the furnace so each building can get full temp water. But if space in the back of the furnace is an issue then maybe a primary loop to the first outbuilding with a manifold to pump other directions might be easier.
Just not enough info to know quite what to say.
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Mlappin what the missus says won't be a concern. I wear the pants in this house. ;D
Gee . For a second there I thought she was going to see what I wrote......
Seriously though I have full authority in the outbuildings. She uses the term " permission" but you know how it is.
E Yoder I tried to post a picture of my situation but can't for some reason. Basically my wood doctor is 125 feet from my house. Towards the house about 15 feet from the owb is building no 1. Further towards the house another 20 ft is building no 2.
It would likely be easier to branch off the house and feed building no 2 , then no 1 , then return to the owb but the house lines are buried and have a huge deck now built on top of them. For that reason ,I'd just as soon leave them alone unless there is a compelling reason to change things.
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So from what you are saying you would like to basically reroute the return line through the buildings... except it's buried. Correct? I wouldn't splice underground!
Since you have the rehau already buried from the furnace to the first building (I think?) I'd tee off before the house pump (to get full temp water) and pump a primary loop through both outbuildings, teeing off secondary loops for infloor, cast rads (which have to start and stop anyway) or whatever. You probably can catch the air handler coil(s) in the building(s) in that loop if they're not too big and strip off too much heat. If you don't want to run pipe to the second building you can extend it later as Pex is very easy to work with.
If you want to get fancy you could with several relays you could make the "outbuilding primary loop" pump come on only when the air handlers , infloor, etc are actually calling for heat. Basically you'd have one relay per "zone" sending the same 120v. power into that main pump that pushes the loop.
Or just let it run! That would be much easier.
Wondering what RSI and others think tho.
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I am not sure if I missed it but I didn't see if either of the buildings are going to need antifreeze. Is the infloor heat going to have any chance of freezing?
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Just thinking here....
If you wanted to do antifreeze in the buildings you probably could put a standpipe teed off the loop in the outbuildings. Would function the same as the fill pipe on the stove. Pump away from that point through a flat plate on the house return, then through the buildings and back to the standpipe. Just fill the standpipe with a water/glycol mix.
Then the house loop would need the bigger pump to supply enough flow for everything.
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The wife was a air force brat and lived in more than one house that had the old cast iron radiators, seems being rentals the landlords never kept the boilers working very well and it was always cold in those house. Personally I like the cast iron ones in our local tavern, turn a chair then sit in it ninty degrees so you can lean your back right on em.
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We actually have 4 of them in our home, one of the large ones in the kitchen dries my insulated pants all winter!
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Yoder...nope. Definitely dont want to reroute anything that is buried. I only commented it would likely be easier from a pumping point of view.
I wasnt planning on glycol anywhere.I dont have it now and my house has been heated this way a dozen years. I just make darn sure the fire stays lit and if the power goes out I run a generator to keep the water circulating. This is my only heat source so a generator is always on standby incase of power outage.
Yoder you are correct in that the rehau is already buried between the owb and the building and also between buildings. I did this when the buildings were being built, knowing this day would come. Ive not heard of standpipes yet so I will do some reading to get educated on that possibility.
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What I meant by a standpipe is just a vertical section of pipe teed off in one of the buildings to act as a small reservoir to fill with glycol. So scrap that idea.
I'd just pump direct off the stove outlet to the buildings.
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Does the boiler not have 2 sets of connections? If it does, using them would be better than teeing off the house connections.
If it doesn't then tees on supply before pump and return is the next best option.
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Does the boiler not have 2 sets of connections? If it does, using them would be better than teeing off the house connections.
If it doesn't then tees on supply before pump and return is the next best option.
:post:
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Nope. Only one set of connections.
So are you saying to tee before the pump on the supply line , and another tee on the return just before it returns to the owb?
Rather than the two close tees on the existing return line we discussed previously?
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Yes, that would be better. Otherwise you will have to increase the flow through the house which will just use more energy to pump and put more wear on the system.
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Yes, that would be better. Otherwise you will have to increase the flow through the house which will just use more energy to pump and put more wear on the system.
:post:
I agree. Especially since now we are designing it to be able to pull two buildings on the second line.
If the outbuilding loop is teed in before the house loop (on the single outlet)and if the outbuilding loop starts and stops it will need a check valve in it to prevent the house loop from making it flow backward. If both run continuously then no check valve is needed.
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Thanks again guys! I will ponder over all the suggestions and try to come up with a schematic or even a sketch to be sure I am following you all correctly.
On a bit of a side note, can you recommend an easy way to transition from kitek to something that isnt prone to leaking? And are special tools needed to use it? Someone suggested I have to get an expander?? to adapt to kitek.
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I've never used kitec but from what I'm seeing online it was just a particular brand of Pex al Pex. So any Pex al Pex fitting should work, I would guess. Readily available from Badger pipe or other online sellers. I'd call badger.
But from what I read the zinc in the original kitec fittings reacted with the aluminum in the Pex al Pex pipe and can permanently damage the piping. ?? Hope not in your case. There are settlements going on.
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I think Kitec was the original pex-al-pex. It was 25mm ID and most now is 26mm. I think Badger fittings are actually 25mm because they always seemed too loose and leaked worse on 26mm PAP.
I have been using the 26mm PAP fittings on kitek and it seems to seal better. You will need a proper reamer tool to make them fit. It takes some effort and stretches it a bit but the flat spot in the pipe isn't as bad afterwards.
The original Kitec fittings didn't have the plastic spacer in them so the aluminum was touching the brass. That was part of the problem.
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Interesting, goes to show experience beats googling any day.
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Ok off to search for badger and hopefully find a reamer there as well as fittings. I have a bunch of brass tees and compression fittings for ordinary pex so one fitting to get away from kitek and I should be set.
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I would get them from OFS and get their 3 way reamer / bevel tool.
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Thanks RSI.....a google search for OFS brings up a lot of places but none appear to be what I'm looking for.
Can you tell me what OFS stands for?
I found Badger but there doesnt appear to be reamers available there.
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Uhh nevermind. Its amazing the clarity a coffee will bring lol.
Outdoor furnace supply.....sound right?
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Yes, that is it.
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So any suggestions for a Canadian source ?
Between the exchange rate and shipping this gets pricey fast.
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How many fittings do you need?