I m just getting started to figure out how to set up to run my system that has a wood fired boiler in the garage with aprox 1000 gallons storage under the house. My first concern is the configuration of the heat exchanger in the tank. Has anyone tried used anything other than copper? The storage tank is made of concrete. Right now we're heating with a woodburner in the living room and it's cozy enough but Iwould like to use the in floor tubing that we installed eventually. Any feedback would be greatly appreciated as any contractor in the area seems to want to retire on my job alone
HELP wood boiler in garage-heat storage under house
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Welcom to the forum. You will find no better source of information or help than this group. What you are talking about has been done by many, perhaps most, of the folks here in one form or another. If you search for various topics, you will find threads of information...and many, many hours of reading. Welcome!
Hunderliggur
Minister of Fire
Recent threads have talked about using surplus cast iron radiators as heat exchangers in a tank like yours. Copper has excellent heat transfer but at a price, if the radiators are free (or nearly so) you can use as many as you need. They make great thermal mass too!
Another quick note....there's a recent thread on placing your boiler in the garage. I debated this myself quite a bit...and everyone has a different take. But ask yourself carefully how you feel about a roaring fire in your garage in the event of a mishap....like gasoline spill, sawdust in the air, etc. Many codes forbid this apparently, yet around me I know many people who heat their garage with an old, inefficient wood stove/furnance. Sure would be nice to walk out in the skivvies to tend the beast, but I know for me, I'd be constantly concerned, so mine is in its own dedicated building. Even better, would be nice to know all the lost heat went into the garage. But when the kid is working on the minibike and the gas line is accidently disconnected and the tank dumps on the floor.... Now I'm personally a bit anal on the subject, as I had a brother die in a house fire 35 years ago when just the above happened, albeit with slightly different circumstances. Culprit there was a gas fired hot water heater...that ignited the gasoline as it ran towards the floor drain by the hot water heater. Personally, I hate natural gas.....yet about 5 billion people on Earth use it everyday. And if they ever drill for marcellus shale gas on my property, perhaps I can actually retire someday....
flyingcow
Minister of Fire
IMO the concrete tank should be insulated. I think you will loose a lot of heat.
The infloor heat you could install yourself to save on labor costs. I installed my staple up and then had an installer do the final hook up to the manifold, which he installed on a previous visit.
The infloor heat you could install yourself to save on labor costs. I installed my staple up and then had an installer do the final hook up to the manifold, which he installed on a previous visit.
As far as the heat ex, I used about 750 feet of 1/2 inch PEX for a while. It would not handle the output of my new boiler so I changed to copper. I now
have 2 x 100 foot coils of copper and that will handle 100k btu with a boiler output temp about 30 degrees higher than storage top temp. The PEX was 4 x ~180-190 feet
and if I had to guess was about the same as 100 feet of copper. If I were to guess I would say pex would take 4 x 300 feet of 3/4 inch... the price starts to approach copper
when you need that much.
have 2 x 100 foot coils of copper and that will handle 100k btu with a boiler output temp about 30 degrees higher than storage top temp. The PEX was 4 x ~180-190 feet
and if I had to guess was about the same as 100 feet of copper. If I were to guess I would say pex would take 4 x 300 feet of 3/4 inch... the price starts to approach copper
when you need that much.
kabbott said:
Pretty much resigned to running two flat plate heat exchangers.One for charging the tank one for bringing the heat to the radiant floor loops.
Planning on two pressurized systems. Hx#1 to boiler & Hx#2 to floor loops
The problem is----I have to run dip tubes for heat exchangers into my unpressurized storage tank. The only access I have to the tank is a 16" by 16" opening on top. I'll need to lift the stored water at least 3ft to reach the heat exchangers.
Do I need check valves on the pump inlets feeding the heat exchangers?
Will I need to over-size those pumps?
I am not sure what your loads are... I would not use 2 flat plate ex, why not use 1 and use 2 pumps to reverse the flow on the tank side
of the flat plate. Use primary/secondary system on boiler side with the flat plate plumbed into the primary loop. Or better yet a 4-way valve
to swap the top/bottom dip tubes when charging/recovering the tank
The money saved on the second flat plate could buy a bigger single exchanger system + the extra pump or 4-way valve.
Not familiar with p/s... check out the sticky https://www.hearth.com/econtent/index.php/forums/viewthread/13877/
of the flat plate. Use primary/secondary system on boiler side with the flat plate plumbed into the primary loop. Or better yet a 4-way valve
to swap the top/bottom dip tubes when charging/recovering the tank
The money saved on the second flat plate could buy a bigger single exchanger system + the extra pump or 4-way valve.
Not familiar with p/s... check out the sticky https://www.hearth.com/econtent/index.php/forums/viewthread/13877/
stefan66 said:
Yes, I do that now with my in tank coil.
If you reverse 1 side you should reverse the other... that means dual pumps on both sides. A better route would be single pump on each side and a 4-way valve that would
swap the top and bottom dip tubes. Someone on the forum is using this method although I can't remember who.
Try a search for 4-way valve???
Hunderliggur
Minister of Fire
Trzebs13
Member
bpirger said:
I can only speak for myself but I do love having mine in my attached garage. Now I'm as paranoid as the next guy about starting my house on fire. I just built it I sure would not want it to burn down. So what I did was, I installed a sprinkler system in the boiler room. It would certialy be a big mess if they went off but I can deal with that. The thing I live it that my garage is finished off and stays about 60 deg all the time just from the heat loss of the boiler. And yes I do fire up in my skivvies. And if you add up all the trips you make to the boiler. Some people will say that they only go to theirs twice a day. Well here I burn for usually 6+ months. So that is at least 360 trips back and forth to another shed out side. And I'm sure that it ends up being more. But just remember common sense goes a long way. Be safe and think ahead.
Trzebs13
Member
bpirger said:
I can only speak for myself but I do love having mine in my attached garage. Now I'm as paranoid as the next guy about starting my house on fire. I just built it I sure would not want it to burn down. So what I did was, I installed a sprinkler system in the boiler room. It would certialy be a big mess if they went off but I can deal with that. The thing I live it that my garage is finished off and stays about 60 deg all the time just from the heat loss of the boiler. And yes I do fire up in my skivvies. And if you add up all the trips you make to the boiler. Some people will say that they only go to theirs twice a day. Well here I burn for usually 6+ months. So that is at least 360 trips back and forth to another shed out side. And I'm sure that it ends up being more. But just remember common sense goes a long way. Be safe and think ahead.
jebatty
Minister of Fire
Flat plate hx's perform best in counterflow. I've been looking for, but have not yet found, what the down-rating might be for parallel flow, and I think it is significant. If you're going to reverse flow, you really ought to reverse flow in both direction to maintain counterflow. Another possibility might be to substantially oversize the hx and that might address the issue, but I don't know enough to have confidence that this would be the right path to take.
A hearty thank you to all.So good to see an honest usefull sharing
of information.Flat plate no longer an option.Bit the bullet today
and bought 3/4" copper for heat exchanger.Currently using an
old "Franks Piping"? boiler but eventually going to buy a newer
gassifying type.1" feed and return from boiler.Planning on 2 parrallel
runs of copper in bottom of tank-each run 60 ft. Is this enough
of information.Flat plate no longer an option.Bit the bullet today
and bought 3/4" copper for heat exchanger.Currently using an
old "Franks Piping"? boiler but eventually going to buy a newer
gassifying type.1" feed and return from boiler.Planning on 2 parrallel
runs of copper in bottom of tank-each run 60 ft. Is this enough
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