Tony Davidson wrote:I'm tinkering with mass inside my stove, and overall I like it. But it does smoke more when the door is open.
Three of eight bricks used as a ceiling have cracked this fall, fire bricks might last longer. There is a two inch gap between my ceiling and the stove ceiling and a six inch plus hole in my ceiling to allow smoke to pass.
Ideally the thermal mass is outside the firebox because otherwise the thermal mass will maintain a lower temperature in your firebox which will hinder complete combustion and you will go through 2-3 times as much wood through the winter trying to stay warm. And when your fire does burn out, all the heat in your thermal mass will go up the chimney. Well, not all of it, but most of it. Thermal mass works both directions. It might take a long time to cool down but it also takes a long time to reach high temperatures which is what you want in your firebox.
Secondary combustion works best when the top of the firebox can reach 900-1200 degrees F which is why modern stoves tend to have insulating rigid mineral board and/or ceramic insulating blankets for smoke shelves. It increases the heat output per cord dramatically and reduces hazardous (and inconvenient) build up of creosote. Less time spent cleaning your chimney, cutting wood, packing wood in the house and stacking wood = more time to read, drink beer, eat, have sex, hunt, etc. = more happy!