Learning from my mistakes in my initial build, as well as wanting to try new ideas, I’ve torn down the wood boiler and began to modify it. I also am using higher end materials instead of homemade concoctions. Here’s my progress so far:
Now I will have double the firebox space. To control combustion, I’m making a partition in the rear of the stove where secondary combustion will take place. The entry to this partition will be low and fairly small. This should also help increase burn time and prevent runaway combustion. Here’s a picture showing the partition construction from the primary burn chamber:
I’ll fill in the gaps with ceramic fiber insulation and coat the whole face with furnace cement. I still haven’t figured out exactly how I’m going to inject secondary air, but I have a few ideas. The firebrick will heat up and help maintain the temperatures necessary for secondary combustion to occur.
Here’s a view of the actual chamber itself:
Note how it has a small entry, but then rapidly opens up into a fairly decent sized chamber. I’m hoping that this will promote turbulence and encourage mixing with secondary air for a more complete combustion before it goes into the stovepipe.
Before I do the final installation of the partition, the ceramic fiber blanket will get a rigidizer applied to seal in the fibers and provide a hard wearing surface.
Next week, I’ll show how I plan to insulate the stovepipe and add my hot gas to water heat exchanger inside.