I’ve been able to make a good deal of progress this week on the boiler. Next week, I should be able to build a small fire to cure everything. Then it’ll be off to the plumbing side of things. Here’s a video documenting my progress and revealing a quick peek at the hot gas to water exchanger:
Since making that video, I’ve gotten the top part of the grate constructed. It still needs the support structure to keep it from bending under heat.
Note all the holes. This is the same kind of material I used on my concrete block rocket stove and it works great.
As you can tell from the above photo, the easiest way for the gases to make it to the secondary combustion chamber is to travel down through the grate and out the rear. Using the manifold I showed in the video, most of the air will be directed under the grate to encourage good secondary combustion and to superheat the tiny coals that drop through. This will create a burn that produces very little ash. The ash that is produced is light and fluffy and is easily scraped out between loadings.
Hopefully the weather will hold next week. On my list of things to get accomplished is to finish the support system for the grate, install the secondary air injectors, finish the air inlet manifold, and insulating the door.