Definitely does help! Good to hear that you’ve done something similar with success. I think that’ll solve my issues. The first time I really filled it, it gave me a 12 hour burn, but the problem is that if I keep filling it that high, I just keep getting more and more build up on the sides of either unburnt coal or ash, so it’s hard to maintain it.lee192233 wrote: ↑Thu. Mar. 18, 2021 10:54 pmHi
With my Big Jack I added fire brick to allow the coal to only sit above the grate. Any true coal burning furnace has grates under the entire firebed. Here's a picture with the fire out. My firebox is approximately 22x12x12". When I load it up I can get about 90 lbs of nut size coal in. The deeper the firebed the better the burn will be.20210220_060539.jpg
Here's a picture that shows how high I have it loaded up. This was after 12 hours with outside temps around 0° and the house was at 72°. When I load it up the coal is at the top of my firebrick. 20210213_053334.jpg
I would try adding brick to keep your coal above the grates. That way you won't have a bunch of unburned coal on the sides. Then when you load it up don't be afraid to fill it up. You should be able to get at least 200 lbs in that firebox. I can get easy 12 hour burns with my furnace even when below 0 at night. Coal is 100% controlled by the amount of combustion air. Make small adjustments and give plenty of time to see the result. I also take notes of my settings and performance changes. It makes things easily repeatable.
I hope my ramblings help,
My boiler is “specifically” designed for coal, warnings all over about how if you burn wood in it, it’ll void the lifetime warranty...but the design sure tempts one to burn wood in it!