Harman SF-250 draft problems w/Bitum. coal

You must live in central Utah to be able to get coal straight from the mine. I live in northern Utah and to my knowledge there is no "true" hard coal available and what is sometimes called hard coal around here is actually soft coal with lower sulfur content. Do you know the quality of this coal?

How much lump coal are you putting in at a time and are you using large (football size or larger) size in this? If you are the fire would be huge with a lot of smoke and is probably too much for that chimney so maybe if you try smaller pieces of coal and see if it works better. Does wood burn well in it without smoking you out?

We use softball sized piecesin it and we can't even really get wood to burn properly at this point.

Ok, I think it must be the chimney as was posted earlier.

In an earlier post you mentioned there was another chimney in the house. I know it could be a lot of work but you could move the stove to the chimney proven to work and try it there. Then you would know for sure if it's the new chimney that's the problem.

If I understand right (I may not, its getting late), you have a 6" galvanized pipe stuck into the top of the 8x8 chimney as an extension? If this is correct, it won't work. The internal area of the 8x8 tile is like 64 square inches, but the cross section of the 6" pipe is only about 28 square inches. This is way too much restriction, especially at the top of the chimney where the differential pressure is lowest. Even 8" round pipe only has a cross section of 50 square inches, and would not work well. If you need to extend the chimney in this way, try 10" pipe. If you "square" the end, it may even fit well into the 8x8 chimney tile. Hope this helps.

rockwood wrote:Ok, I think it must be the chimney as was posted earlier.

In an earlier post you mentioned there was another chimney in the house. I know it could be a lot of work but you could move the stove to the chimney proven to work and try it there. Then you would know for sure if it's the new chimney that's the problem.

We removed the old chimney so we are moving the old stove in to see if it has the same problem.

We will try a larger extension, the extension was put on just to see if it would help the draft issue and nothing changed, so I really wonder if it is a length issue? AAggrrhhh!

what i found with bituminous in my sf-260 was that it burned very fast if enough draft was induced to clear out the volatiles. before i did this, i built up so much soot in my 8" chimney, it backed up into my basement. what a mess! soot covered everything. so, try adding small amounts at a time to maintain a better air-fuel ratio, don't load it up for a max burn time run. alternatively, it burns wood excellently.

We are having the same problem. We can only get bit. coal here in Colorado Springs, so that's what we're burning. Today the high was 11 degrees, and I had smoke backing into the house all day. The smoke kept puffing out of the draft wheels. We also have the sf 250. The dealer installed our stovepipe. It is 6" single walled pipe inside, and then 6" insulated double walled pipe outside. It goes about 3-4ft. above the eve but we live in a Cape Cod style house so it doesn't go above the peak of the house. Any ideas? I'm going to call the dealer tomorrow.

" Any ideas?"

as someone who has a lot of experience heating with bituminous coal, trust me, your problems are primarily with your chimney. you need strong draft, minimum -.06 and at least an 8" flue the WHOLE way from the stove coller to the end of the stack. anything smaller and soot buildup will clog it too easily, with an 8" minimum chimney, if you burn a hot fire at least once a week, the soot buildup will not cause a draft problem as it will periodically burn/blow out. your chimney need to be taller, MUCH taller; it should really be taller than the peak of your roof and should be an interior chimney if possible an exterior chimney further reduces your already dismal draft caused by an abysmally short chimney.

I had a similar draft/smoke rollout problem last year with my handfed homemade stove. I too had a 6" chimney a horizontal section, and a similar height chimney on the outside of my house. Same setup as you, only I have SS insulated chimney, and a basement stove. I did lots of tinkering, from hinged smoke flaps on the load door, single-wall extensions to the chimney, 45 degree elbows to replace the 90, etc.

I never did solve the problem, as I installed a stoker this year instead. However, I believe what I really needed to do was get an 8" chimney, at the very least. There's just too much fuel being burned, creating too many gases to get out a 6" hole.

Prior to the handfed stove, I had a woodstove. It was borderline - as long as I had a clean chimney and a hot fire, I could avoid smoke. But with the coal stove, smoke rolled out even with a clean, hot chimney. It's very frustrating.

Don't get down on the Harman stove. I think it's a really good stove, and I know there are a few people using them in Wyoming that have good success.

I'd take Berlin's advice and upgrade the chimney. Problem is, it's not cheap, as you know.

Good luck,

Steinke in Wyoming

What really stinks is that we just spent $4000 putting this stove and chimney in. Should we go back to the dealer/installer? It seems as if he should have know this, but maybe I'm expecting too much. Our stove is also in the walk-out basement, so the chimney goes up three stories.

I have a sf250 and found out last year that you must clean the heat exchanger box. The large bolt on the top front take and loosen that until you are able to get the plate off. Then take coat hanger and make sure that the two smoke chambers are clear. Vacuum out the heat exchanger from the front and back. Hope this helps if not now maybe in the future. Brian

hillsbillies wrote:We are having the same problem. We can only get bit. coal here in Colorado Springs, so that's what we're burning. Today the high was 11 degrees, and I had smoke backing into the house all day. The smoke kept puffing out of the draft wheels. We also have the sf 250. The dealer installed our stovepipe. It is 6" single walled pipe inside, and then 6" insulated double walled pipe outside. It goes about 3-4ft. above the eve but we live in a Cape Cod style house so it doesn't go above the peak of the house. Any ideas? I'm going to call the dealer tomorrow.

when i had smoke back into the house, the problem was that the bituminous volatiles condensed on the spark arrestor screen on the chimney cap. plugged it solid. and this was on the end of 30' of triple wall 8" stainless snaked through my existing masonry chimney. my installer was kind enough to remove the screen.

Hi everyone!
I had my installer come out and sure enough, the chimney wasn't high enough. (He never inspected it after his guys put it in) He also removed the spark arrester screen off of our chimney, and now the stove works like a dream! It's running so hot and clean now that I can see through the window even with burning Utah bitum. coal!! Hooray! Thank you for all of your input!! My stove actually drafts!

I bought a new SF-250. It drafts very poorly in warmer weather (anything over 30 degress F). The colder the weather the better the draft. That could be part of your issue depending on where you live.