My house consists of two bedrooms and a bathroom off of a big, central room. I heat it all pretty well with a woodstove, so I use a lot of wood. I recently saw an ad for a device that recovers waste heat from the chimney and returns it to the room. Does this work? I’d only buy it if it adds enough heat to the house to allow me to burn less wood.
These devices can present a safety concern. If you reclaim heat from the gases exiting the stove, you cool the gases. Air in a woodstove exhaust pipe or chimney needs to be warm in order to rise and exit the house. If this air is too cool to rise, toxic carbon monoxide can become trapped in the stove and then enter your house when you open the stove door. Also, cooler flue gases can result in greater creosote formation.
As for your question about the potential for these devices to reduce the amount of wood burned, the answer is different for each stove. It depends on such things as the length of your stovepipe, the stove’s design, the temperature you bring your stove to, and how seasoned your wood is. Because it’s tricky to accurately predict this heat-reclaiming device’s consistent wood-saving potential, and because of the safety considerations, I recommend considering more reliable approaches to reducing wood use. I strongly suggest looking into ways to tighten up your home, in order to reduce the leakage of cold, outdoor air into the house and the loss of warm air.
A good job of air sealing and insulation can make a significant difference in heating costs, no matter what kind of heating system you use. The most comprehensive approach is to consult with a pro. A Home Performance with ENERGY STAR® contractor can do a whole-house assessment to find and fix the causes of high energy bills. Efficiency Vermont offers up to $2,500 in rebates for improvements completed by these specially trained and certified contractors. Visit our Home Performance with ENERGY STAR section for a list of contractors and more info. Good luck and stay warm!
Bob for The Home Team