Hello coal experts. Thanks for the help so far regarding my homebuilt bituminous burner. Stove has been burning well, putting out more heat than necessary for this time of year. Gotta get the wife to hold back on the fires some.
The advice you gave me for getting a better burn by closing the secondary air is working great - see link below for that thread:Burn seems very erratic.
Now for the next issue. Ever since the first burn (with wood to get some confidence), I get smoke coming out the load door whenever I open it, especially with a fresh load of coal or wood, when most smoke is present. During mid burns, if I open the door, I can see what little smoke is being produced still tends to come out the door instead of the chimney.
I'll admit that I have a 6" diameter chimney. It is 15' high. The stove is in the basement, so I have double wall smoke pipe rising 2' from the stove, then an elbow, 12" of horizontal run to my wall thimble, where I enter a triple-wall tee, and head up the side of the house to the roof. The chimney could use another foot or two of height to get above my roofline (it's 10' from my roof peak horizontally, and the same height as my peak.
My draft seems OK - would be better with 8" I'm sure. But I can really get the fire rolling, and then the draft seems fairly impressive, getting the stove to 600 degrees occasionally. Even then, smoke will come out the door if I open it.
Here's what I'm wondering. Is it possible that I did not leave enough space above the load door opening? I have attached a 2-page PDF file showing a CAD view of the stove drawing. I have about 4-1/2" between the top of the door opening and the top of the stove. I have a baffle plate installed, and the 6" stove collar sticks down into the stove a few inches. My reasoning for building the collar this way was to force the heat to "roll" a little more to get more heat transfer.
To attempt to solve the smoke issue, I tried to reduce my door opening size a little last night by clamping a piece of steel inside the door opeing near the top. It seemed to help some, but it was difficult to tell because I did not have quite the right size scraps.
I'm really hoping the cause of the smoking is not the chimney size (expensive). But if that's truly the problem, then I just need to bite the bullet and go with 8".
BTW - I was looking at Harman's SF-250, and they use a 6" stove collar, and the model I saw has a metal flap that swings down when you open the door - appears to reduce the door opening size. Maybe I need something like that.
Thanks for the advice. I keep saying I'm going to post the plans I drew up, but I'd like to get some of these issues sorted out before I give out the CAD files, to keep others from making my mistakes.