Wish I had the money for a new cat stove or better yet a massive masonry heater, to save on wood and pollution and all that. But I’m a poor slob, ha ha! Probably not a lot of rich guys in here burning wood for their heat, right? Anyway, my house came with a pre-EPA air-tight Fisher Grandpa Bear smoking dinosaur. I think I get decent efficiency out of it during the day with a series of small but wide open hot fires, small enough that I can have the vents wide open and not exceed 550F flue temp (I work from home and can watch it pretty close). Probably not as efficient as with secondary combustion, but I must be doing pretty good because I can’t see much coming out of my chimney after startup. The problem is, of course, at night. In order to make it through the night, I gotta fill that dinosaur with wood then close it down, and that’s when energy (and my hard work) really gets wasted. I got the glazed creosote to show for it (but the Anti Creo Soot powder is really helping with that).
So, what can a poor slob do to make his pre-EPA smoker more efficient?
My first thought was about a retro cat conversion. According to MEN, there used to be a bunch of options for this 20-25 years ago ((broken link removed to http://www.motherearthnews.com/Do-It-Yourself/1984-11-01/Retrofit-Catalytic-Converters.aspx)). They experimented with their own ‘in the box design’ and saw a 15% increase in efficiency ((broken link removed to http://www.motherearthnews.com/Do-It-Yourself/1983-01-01/A-Catalytic-Converter-You-Can-Build.aspx?page=7)). Here’s a nice in-the-box model called a Smoke Genie (http://books.google.com/books?id=WuJsvsxlHv4C&pg=PA68&lpg=PA68&dq;="smoke+genie"+wood+stove&source=bl&ots=DpQofdqYUl&sig=0lYxB-1HJhtV-8OqNJaGEuOmjOA&hl=en&ei=baUxS6nIApTllAfSj5ipBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAwQ6AEwAA#v=onepage&q="smoke genie" wood stove&f=false), but it doesn’t look like they lasted. There is one model that is still available, but it is out-of-box, made to sit on the flue collar ((broken link removed)). It looks good, on paper, but I cannot find a single person with any experience with the thing. Moreover, a previous MEN article says the flue models they played with weren’t very good anyway ((broken link removed to http://www.motherearthnews.com/Do-It-Yourself/1983-01-01/A-Catalytic-Converter-You-Can-Build.aspx?page=3)): “we developed several early versions that attached to the stovepipe outside the firebox, and at that location our attempts to keep the catalyst active at low burn rates weren't very successful. In the test stove, for instance, a burn rate of two pounds of wood per hour produced a stack temperature of 250°F at the exit to the stovepipe. At that temperature, the catalyst died after a few minutes of activity. Furthermore, the chance of relighting the catalyst after fuel reloading was an iffy matter, at best.” The idea still ain’t dead though: stovepartsplus.com currently has a banner talking about their NEW product “The Wood Stove Rx Catalytic Retrofit System” but without any details (http://www.stovepartsplus.com/Merchant5/merchant.mvc?Store_Code=SPP&Screen=CTGY&Category_Code=JOTUL).
So I’m not too keen on the retro cat option at the moment, based on what I have seen so far.
The other choice, in my mind, is to continue to burn short hot fires when I can but add more thermal mass to help carry heat through the night. I certainly can’t add many tons of mass, given that I don’t have proper structural support below, but in theory, every little bit helps. I’m not talking about a true masonry heater here with unbridled HIGH temp fires and strategically extended flue lines, just more mass around the stove to average out temperature swings. Here’s one cool example using cob: (broken link removed to http://www.lowimpactliving.com/blog/wp-content/uploads/2009/04/cob-house-stove.jpg). This makes me wonder though…isn’t heat output a function of temperature difference between in and outside the box? If the hot box is facing open air at ‘room-temp’ then it must be giving up more heat than a hot box that is facing massive masonry that is itself pretty hot, right? And so that extra heat is going up the chimney?? I have read a lot of posts here about soapstone, and it sounds like a lot of the soapstone stove owners wonder the same thing when they can’t achieve the same surface temps as they can with the top stone off. Sure, some amount of heat is stored in the mass and later released gradually, making the heat release phase LONGER, but do you actually get more total heat out your fuel, or really less? Or does the masonry blocking heat release from the stove make it hotter, so you crank it down a little tighter, thus making it burn longer? A bit of a tangent, I know…my goal is to get a longer heat cycle, but I am just curious if that comes with a price of less efficiency…
end pt. I
So, what can a poor slob do to make his pre-EPA smoker more efficient?
My first thought was about a retro cat conversion. According to MEN, there used to be a bunch of options for this 20-25 years ago ((broken link removed to http://www.motherearthnews.com/Do-It-Yourself/1984-11-01/Retrofit-Catalytic-Converters.aspx)). They experimented with their own ‘in the box design’ and saw a 15% increase in efficiency ((broken link removed to http://www.motherearthnews.com/Do-It-Yourself/1983-01-01/A-Catalytic-Converter-You-Can-Build.aspx?page=7)). Here’s a nice in-the-box model called a Smoke Genie (http://books.google.com/books?id=WuJsvsxlHv4C&pg=PA68&lpg=PA68&dq;="smoke+genie"+wood+stove&source=bl&ots=DpQofdqYUl&sig=0lYxB-1HJhtV-8OqNJaGEuOmjOA&hl=en&ei=baUxS6nIApTllAfSj5ipBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAwQ6AEwAA#v=onepage&q="smoke genie" wood stove&f=false), but it doesn’t look like they lasted. There is one model that is still available, but it is out-of-box, made to sit on the flue collar ((broken link removed)). It looks good, on paper, but I cannot find a single person with any experience with the thing. Moreover, a previous MEN article says the flue models they played with weren’t very good anyway ((broken link removed to http://www.motherearthnews.com/Do-It-Yourself/1983-01-01/A-Catalytic-Converter-You-Can-Build.aspx?page=3)): “we developed several early versions that attached to the stovepipe outside the firebox, and at that location our attempts to keep the catalyst active at low burn rates weren't very successful. In the test stove, for instance, a burn rate of two pounds of wood per hour produced a stack temperature of 250°F at the exit to the stovepipe. At that temperature, the catalyst died after a few minutes of activity. Furthermore, the chance of relighting the catalyst after fuel reloading was an iffy matter, at best.” The idea still ain’t dead though: stovepartsplus.com currently has a banner talking about their NEW product “The Wood Stove Rx Catalytic Retrofit System” but without any details (http://www.stovepartsplus.com/Merchant5/merchant.mvc?Store_Code=SPP&Screen=CTGY&Category_Code=JOTUL).
So I’m not too keen on the retro cat option at the moment, based on what I have seen so far.
The other choice, in my mind, is to continue to burn short hot fires when I can but add more thermal mass to help carry heat through the night. I certainly can’t add many tons of mass, given that I don’t have proper structural support below, but in theory, every little bit helps. I’m not talking about a true masonry heater here with unbridled HIGH temp fires and strategically extended flue lines, just more mass around the stove to average out temperature swings. Here’s one cool example using cob: (broken link removed to http://www.lowimpactliving.com/blog/wp-content/uploads/2009/04/cob-house-stove.jpg). This makes me wonder though…isn’t heat output a function of temperature difference between in and outside the box? If the hot box is facing open air at ‘room-temp’ then it must be giving up more heat than a hot box that is facing massive masonry that is itself pretty hot, right? And so that extra heat is going up the chimney?? I have read a lot of posts here about soapstone, and it sounds like a lot of the soapstone stove owners wonder the same thing when they can’t achieve the same surface temps as they can with the top stone off. Sure, some amount of heat is stored in the mass and later released gradually, making the heat release phase LONGER, but do you actually get more total heat out your fuel, or really less? Or does the masonry blocking heat release from the stove make it hotter, so you crank it down a little tighter, thus making it burn longer? A bit of a tangent, I know…my goal is to get a longer heat cycle, but I am just curious if that comes with a price of less efficiency…
end pt. I
