Just read "
Wood Heat: Is it right for you?" in
Mother Earth News, issue 236. No, it doesn't talk about rocket mass
heaters, but briefly weighs different
wood heat options. Cost-wise: it offers the website
www.hearth.com to calculate fuel cost. It also suggests that you calculate in paying yourself minimum wage for time spent chopping the
wood if you do it yourself. It also offers the EPA website:
www.epa.gov/woodstoves/basic.html, and says stoves they certify have an average of 70% efficiency. (I
think RMHs have 90%?) The article talks about different options, including wood boilers or central furnaces, although these are harder to find high efficiency. Pellet stoves could save money and hassle, but you can't make them yourself, and they require electricity to run their fuel auger, fans, and controls. (reliant on the grid) Lastly, the article says that one mistake not to make is running your chimney out the wall and up in order to leave the house. Running the chimney straight up through the roof of the house will minimize smoke coming back down and rolling into the house whenever you open the door.