Perhaps the biggest obstacle to overcome is how to get enough air volume to blow the warm air throughout the house. This is a multiple choice question with many correct answers. It varies from situation to situation.
Like others before me, in my anxiousness to get up and running with my brand new stove 2 years ago, I found that out the hard way that 265 CFM doesn’t cut it. I had simply connected the 6” duct from the top of my Alaska Channing III (a dealer-installed option) to the hot air side of the main trunk of my gas forced air furnace and let ‘er rip. Running the stove at 3 or more (medium+ fire level) continuously, after about 24 hours, it was pleasant on first floor (that’s all I’m heating in my 60 year old cape-cod style house). The basement was very toasty, account heat loss through the ductwork, including the extra 9’ or so I added getting from my stove to the furnace duct. My magnetic thermometers also showed 400 degrees or so on the sidewalls and front of the stove radiating freely into the basement as well. So I used a 20” box fan to blow diagonally across the left side of stove to richochet off the back wall and collect the radiant heat from the right side and direct it towards my basement steps. There I had another box fan blowing the air up the steps. Since I fired up in mid February and knowing I’d only run until mid April or so, I figured I’d get by with it as is until fall. The two main failures I had was in not realizing that 265 CFM through the central heating system is woefully inadequate and that I’m wasting lots of heat into the basement. Another lesser problem was that of hot air heading backwards (toward) the furnace plenum from my connection about 4’ away from the furnace.
So, on the advice of a HVAC friend of mine, I cut a 24” x 30” hole in the “down” plenum (cold air side) of my furnace, disconnected my stove from the duct work, and turned on the furnace fan 24x7. It worked very well at distributing heat evenly throughout the house. However…I didn’t like the idea of throwing all that heat around the basement, needlessly (trying) to heat the basement walls, concrete floor, etc. Also, it jumped my electric bill by about $40 the first month. And I’m basically a cheapskate.
So, in Nov ’09, I built a heat jacket for the stove and connected it’s output to the main furnace duct in addition to reconnecting the original duct from the stove. To feed it, I discarded the 265 CFM fan that came with the stove and bought two 405 CFM centrifugal fans online. One I connected to the stove where the 265 CFM fan had been (2 weeks to engineer a custom 6” round attachment to 2x4” square connection on the stove). The other fan feeds the two side panels of the custom made jacket. Each fan draws from a ‘tap’ I made on the living room cold-air returns and I put dampers in to block off drawing cold air through the furnace (possibly sucking warm air backwards through the entire furnace). See my setup here http://nepacrossroads.com/about389-390.html
About ½ way down the page.
I’ve been quite satisfied with the results. Recognizing that the 405 CFM fan rating is with no ductwork attached (“free air flow”), I’m guessing I’m getting 250+ out of each fan due to the ductwork turns, leakage, etc. But if one were to consider the original 275 CFM fan blowing at perhaps 175 CFM or so (how they managed to figure 275 CFM with a 2.3”x4.25” (roughly 12 square inches) feeding a 6” duct (3” squared x pi = 28 square inches, more or less) is beyond me), I’m far ahead of the game pushing 500+ CFM through the ductwork these days.
The two problems of my installation is the significant air flow ‘whoosh’ sound through one of my cold air return vents in the living room, mostly due to a very sharp-edged 90 degree turn just below the vent. I made some adjustments this fall and improved it somewhat. The other minor problem was the ‘back flow’ into the furnace from my connection to the hot-air side of the ductwork. I fixed that this year by the insertion of a tight-fitting sheet of metal into the ductwork between my connection and the furnace. Between that fix and some revisions to the cold-air ductwork, I’ve reduced my coal consumption by about 25% this season over last.
In summary, the three biggest obstacles to overcome are (in order):
1. Getting sufficient air flow through the hot-air system heat ducts
2. Establishing a complete “air circuit” through the stove
3. Getting as much heat as possible from the stove to the living area