I've heard that wrapping my wood stove's chimney – the parts inside the house that go from the stove the the actual chimney – with copper pipes will increase the amount of heat generated.
Has anyone ever tried this? What diameter copper would work best for a typical 7" stove pipe? And how long should the copper be, given a 3' length of stove pipe?
Best Answer
In a woodstove, where the fire doesn't get very hot, you get a lot of unburnt gases. These are compounds that could burn but only at a higher temperature. Instead, they evaporate. As they travel up the chimney, the cool and condense. Over time it builds up. If you then burn a really hot fire, they can finally ignite, and your chimney burns. This can happen when you use a lot of pitchy softwood for a long time (Douglas Fir, for example) and then burn some really dry hardwood (e.g., maple).
If you do something clever to extract more heat from the chimney, you will get more condensed goop in your chimney, so be sure to clean it regularly.
Another way to deal with this problem is to always make a really hot fire. Then almost everything will burn, leaving very little goop in the chimney, and very little ash. That's going to be too much heat for your house, so you have to surround your fire with an enormous thermal mass. That will moderate the temperature. This is the principle behind a "Russian stove", among other names.