Heat raclaimer for pellet stove

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K

ken3698

Member
Jan 14, 2008
46
Western NY
I'm curious about adding a heat rclaimer to my 4inch exhaust pipe. The pellet stove insert is in the center of my house and was thinking of adding a heat reclaim unit in the kitchen (backside of stove)... Is this a good idea? Do they even make them for a 4inch pipe?

Thanks
 
hey ken,I was thinking along the same lines and was going to start a thread on this topic but didn't really know how to address it. I hate to see all that heat going to waste and the temperature on my exhaust pipe is in the 200 plus degree range-just think if you could extract that somehow! My first thoughts though would be insurance-how would that sit with them I wonder.But getting back,I just wonder what would happen say just for example if you ran the exhaust,say through a radiator from a tractor trailer and had a fan behind it....see where I'm going with this.As long as there is no restriction,I think it would pay off.Maybe you had different thoughts on this.....
 
Thanks for the thought...

I just came up with something, My pellet insert sits right on the ceramic tile of our hearth. It get's very hot, due the firebox's thin wall. What if I put some tubbing underneath with a fan blower going into the kitchen end.. It would suck the air out of my livingroom go thru the warm tubes under the fire box and then exhaust into the kitchen. I bet that would give two great heat flows, one from the pellet stove itself and then another from this makeshift tube heat exchanger into the kitchen.

Your thoughts?
 
Be careful. A byproduct of combustion is water vapor. For fuel burning appliances to operate at an efficiency above the mid 80% range, the exhaust approaches or falls below the point where moisture in the exhaust begins to condense. In other words, you need the flue gases to be hot enough to prevent condensation from forming in the exhaust. If you have a high efficiency (90%+) gas furnace you will see a drain tubing coming from it and a stream of water flowing out of the drain while the burner is firing. These stoves are probably running as close to condensing efficiency as you will want to get. If you reduce the heat in the exhaust any further, you may find water running out of it. You may also risk other byproducts of combustion condensing in the flue pipe.
 
Sleepy said:
Be careful. A byproduct of combustion is water vapor. For fuel burning appliances to operate at an efficiency above the mid 80% range, the exhaust approaches or falls below the point where moisture in the exhaust begins to condense. In other words, you need the flue gases to be hot enough to prevent condensation from forming in the exhaust. If you have a high efficiency (90%+) gas furnace you will see a drain tubing coming from it and a stream of water flowing out of the drain while the burner is firing. These stoves are probably running as close to condensing efficiency as you will want to get. If you reduce the heat in the exhaust any further, you may find water running out of it. You may also risk other byproducts of combustion condensing in the flue pipe.
Click to expand...

Thats an awesome piece of advice.
 
IMHO, there is not nearly enough heat going up the stack of most pellet stove for reclamation to be of any value. Even with woodstoves - with vastly hotter and larger stacks - heat reclaimers have gone out of fashion due to increased efficiencies.

A simple answer regarding heat reclaimers for pellet stoves would be "no".
 
My Europa 75 seems to do pretty good at extracting heat. I have about 4 feet up and less than 3 outside. I can put my hand under the cap and it is less warm than the clothes dryer vent. I doubt it would justify the expense. You would be better off doing more weather proofing or adding another stove.

Jerry
 
It must be different for those burning corn, because I saw a web site (http://www.forcornstoves.com/webedit.php?name=exchanger) a couple of months ago advertizing a heat exchanger that attaches to the vent pipe and extracts heat from the corn stove vent. Several testimonials said it worked well to heat a garage or extra storage room. They do say it isn't for pellet stoves due to creasote.
 
What I wanted to try as a experiment is to wrap a say like 3/8" copper tube around the exhaust pipe. Now in the copper tube is water that is held in a storage tank(old hot water heater) and a circulation pump running it around. From there I would tap off to my tankless hot water heater. Went as far as buying some tubing and got a 45 gallon drum just to see what the temp rise would be, but never hooked it up yet.

With my accentra running at a medium the exhaust gets pretty warm(hot)

shayne
 
Philip said:
It must be different for those burning corn, because I saw a web site (http://www.forcornstoves.com/webedit.php?name=exchanger) a couple of months ago advertizing a heat exchanger that attaches to the vent pipe and extracts heat from the corn stove vent. Several testimonials said it worked well to heat a garage or extra storage room. They do say it isn't for pellet stoves due to creasote.
Click to expand...

Thats an interesting design-I wonder if they are aware of this forum.It would be in their interests to have one of these in operation with one of the members here just to test the thing out. In regards to the creosote problem,I wonder a bit about this.I've taken the exhaust run apart twice this winter and maybe have extracted a total of a coffee cup full of fine ash and no creosote to speak of-although I haven't checked the 6" stainless chimney pipe that it flows into,I don't expect problems.When I'm running on higher feed rates,I can't put my hand on the exhaust pipe since it is so hot-I'd rather have that heat in the house where it belongs.
 
Do some research 1st. Water vapor in flue gas begins to condense at 250-300 degrees regardless of the fuel you are burning.
 
flatboy said:
What I wanted to try as a experiment is to wrap a say like 3/8" copper tube around the exhaust pipe. Now in the copper tube is water that is held in a storage tank(old hot water heater) and a circulation pump running it around. From there I would tap off to my tankless hot water heater. Went as far as buying some tubing and got a 45 gallon drum just to see what the temp rise would be, but never hooked it up yet.

With my accentra running at a medium the exhaust gets pretty warm(hot)

shayne
Click to expand...

I am intrigued by this idea. I don't have any heat in my cellar, especially now that my furnace for my forced hot water heat isn't used. I wonder how well flatboy's idea would work if you were to connect this water filled copper tubing to a circulating pump, and then to a length of fin tube baseboard in the cellar below the pellet stove. You could then put a muffin fan behind the fine tube to blow it around the cellar. Obviously it isn't going to heat the entire basement to 70 degress, but it would help a little bit.
 
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