Last summer, Dan built a masonry stove to replace our cast iron wood heater.
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| Masonry stoves are based on ancient technology and are amazingly efficient. |
The gist of how it works is that the firebox is located in a large, empty space called a thermal mass. The thermal mass retains and radiates heat long after the fire goes out.
Last winter, we used it and loved how long it kept the house warm between fires. The downside is that it tends to be a bit smokey with a cold start. Until the mass warms up enough to create a good draft, smoke comes out every time the door is opened, or through any leaks in the masonry. There are tricks for dealing with this (Tests and Tweaks), and usually, people only have trouble at the beginning of the season. For us, however, in our goofy southern climate, there are times when we don't need the stove and let it go out. In a typical winter here, we might restart the stove several times, especially in spring.
Last month, Dan added a smoke by-pass to use when the stove is started up. The by-pass offers a direct outlet for the smoke created when starting a fire. Once the stove heats up and the draft is good, the by-pass damper is closed and the thermal mass can build up heat.
Here's what Dan did in pictures.
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| The first step was to take down the existing chimney pipe. He cleans the chimney once a year anyway, so that got done too. |
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| Installing the damper required drilling a 6-inch hole in the top of the stove. For that, we had to get a 6-inch diamond masonry drill bit. |
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| Here it is from the damper side, where you can see the openings and gap. You can also see how the insulation discs blocks them. |
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| Insulation side |
