Need help fast!

I am completely new to coal/wood burning.

I am having trouble with my Johnson furnace. It is very similar to the Norsman 2500. The furnace is set up in the garage and the 8" stack goes straight up 16' single wall and then another 12' in double wall (near the ceiling and outside). I have a MFD in place also.

I started buring wood first, but I couldn't get a long enough burn (4hrs max). I know part of the problem was the wood I was using. Wood is gone. Got injured and can't split more at this time. So, I decided to try coal. I was told that I need to burn lump (2-6") coal in the furnace by a local coal supplier. My furnace is designed for both. It has bottom fed air and shaker grates. The coal I got is from the Knighthawk mine in southern IL and it is called called raw coal. It is bit coal and ranges in size from dust to 2 foot square blocks. I got it because it is $55/ton. I am located in central IL and the lump coal around here ranges $245-$280 a ton. Brought back 4 tons. 3/5ths is chunks and the rest is fines.

The problem I am having is I can't keep a good hot burn going for any length of time. I tried loading the furnace every way I can think of. All big chunks, all small pieces, mixing them together, differnt sizes in layers, etc. I have even tried getting a good set of coals going, pushing them to the back and then loading again so it has to burn accross the pile and not just from under. I usually get the same overall results. The coal starts burning like mad (flue and ash door open). Leave it until flue gets to about 400-500 then turn the MFD to half way between 1 and 2 o'clock. This slows the fire some and I wait a little longer to close the ash door to make sure there is a good bed of coals. I then close the ash door. If I don't the furnace stays too hot and the coal is gone is just 2 hrs. I have tried playing with the air adjuster on the ash door and the MFD, but a couple hours later the flue temp is down to 250 and won't get any hotter.

In the morning, I have two full trays of ash and about 2-3 gallons of clinkers. This does not include what is taken out during the day. There is not enough heat to restart the fire. Total time 6-7 hours. House is cold.

I'm sorry for the long post, but I am tring to give as much info up front as I can.
P.S. I've done some searching on here and tried some of the tips others have given, but I always get the same results.

Thanks,
Chuck

Hi Chuck, welcome to the coal forum

how deep are you filling the bed? how long are you leaving ash door open?

It sounds like you have a thinish bed of coal and too much draft. this may be related to firebox size as well - it may just be too small. I've burned a lot of illinois coal with so much iron the ash was almost black powder - a dark Burgundy. The key to keeping the fire almost clinker free is to burn it slow, a deep large bed of coals with the underfire air closed as much as possible. Unfortunately run of mine coal like what you're burning is inherently prone to producing more clinkers as there's more ash and debris in the coal than screened/washed or just sized coal - although if you've tried burning lumps/as is etc and have the same results then it's either some of the things i mentioned or the appliance itself isn't well designed; if you were getting a 4 hour max burn w/ wood that tells me that it was a bit undersized to begin with, and coal likes it oversized - bituminous coal w/ low ash fusion temps likes to be smouldered so it doesn't produce clinkers, and although it will produce soot, it won't produce tarry, flamable creosote like wood will.

I have had the bed as much as 2 feet thick and the box is about 27" long and about 30" tall. I think the box should be plenty big. Coal capacity is listed at 100 lbs. The ash is light grey in color with a lot of yellow chunks in it. If I close the air door or MFD any more, the fire goes out. As is, the flue temp stays at 250 for about 4 hrs.

Chuck

250ºF on the stack thermometer is plenty high enough, my hand-fired stove would usually run between 200-350ºF at mid to high fire, and a boiler should run cooler. at the moment I'm out of ideas. I've never had the problem you describe with any bituminous coal. Unlikely, but perhaps it's the coal, mabey it's high ash 15% + low btu garbage, but that's unlikely. The fact that you're getting that much clinker with a coal that's more or less producing grey ash leads me to believe it's got something to do with the appliance itself. or mabey your heating load is too large for the firebox, as you mentioned, burning through a firebox full of wood in four hours means the heat is going somewhere, either you'd have really high stack temps or the heat is being transferred to the boiler and then to the heated space; this seems like a lot of coal, but perhaps that's how much you need.

Thanks. I am not to concerned about the quantity. It is mostly the lack of complete burning and lower temps. The unit is a forced air design and with the wood, I would keep it around 400 and get plenty of hot air. I can't seem to with the coal.

As for the wood, it is mostly cottonwood which turns to dust. It is free and lots of it, but burn fast. That was the reason for the quick burn on it.

Thanks again for the input.

Chuck

apparently i've misread; i thought you had a boiler. What is your stack draft? I've also seen many cases (usually w/ boilers) where the coal doesn't like the forced draft blower to be used; but rather a thermostatic door using natural draft.

ChuckV309 wrote:The unit is a forced air design

I think he means forced "hot" air not forced draft but I could be wrong.

Chuck, how much secondary air (above the coal bed air) are you allowing? 2-3 gallons of clinkers tells me that the fire may be getting too much air burning the coal quickly and all the heat going up the chimney with lots of clinkers as a result however the quality of your coal could be part of the reason too. How long are you leaving the ash door wide open? I'm surprised that you say the fire goes out if you partially close draft.

ChuckV309 wrote:If I close the air door or MFD any more, the fire goes out.

How many times has that happened?
If a soft coal fire is burning well (revved up) then it should keep burning even with limited air. Before you load up be sure you have a good hot bed of coals to start with then be sure to let the new loaded coal get burning good which should only take about 5, 10 minutes at most, then you should be able to start shutting down the air supply and MPD without having the fire go out. If there's lots of fine coal then be sure to leave an exposed area of hot burning coals when you load up the furnace with coal to burn off flammable gasses before they accumulate too much and cause a puffback.

"I think he means forced "hot" air not forced draft but I could be wrong. "

yeah, i think i misread yet again

although much of illinois coal has lower fusion temps, i've burned illinois coal with much lower fusion temps than he's currently burning w/ bands of pyrite 3/4" thick - the ash was a burgundy powder. you can burn coals with low fusion temps if you reduce the underfire air without any clinkers. I looked up knighthawk coal, and all of the mines list around 11,500 btu/lb w/ 10% and as low as 5% ash, so it's doubtful it's the coal causing many of the problems, even if it has a lower AFT; I think there is something about the way he's firing it or the appliance itself.

Ok, here's a question that may give me a better idea of what's going on: When you fill it with fresh coal, how much (if you filled 5 gal. pails - this gives me an idea of how much coal your putting in- it's how i fill all my stoves and stokers) coal do you load each time? such as before you head to bed.

As far as the fire going out, it's possible that because you have so much single-wall pipe and no thermal mass to stay warm (such as you would have with a masonry stack) and the furnace's location in your garage that if you damp down much then the stack suddenly dramatically loses draft - enough that the fire will not stay burning and go out. When you reduce flow through coal via underfire air restriction controlls on the appliance you want the system to maintain strong negative pressure even while reducing flow (this is one of the reasons I don't like MFD's on coal - it prevents this). Also is there any overfire air? If so perhaps these ports are open too much to maintain draft through the coalbed when the underfire air/MFD is closed.

Chuck, do you have any pics of your firebox, stack setup etc, fire while burning?

Chuck it sounds like you and I have about the same size unit's, mine is a boiler but same difference when it comes to the burn cycle. I too live in central Illinois. I have been using Indiana coal from south of Terre Haute , it should be the same coal basically. When you get mine run coal it is not cleaned so you take the bad with the good. No matter what you do you will get some clinkers, and soot. I have the induction fan too just like you. You can chose to use it or not, burns more fuel with it for sure. About the only time I use the fan is to get the fire going good from either a fresh start or an over night burn. That very small pea sized stuff is a real pain to burn, anything wall nut or bigger isn't bad. I am getting over night burns with mine and I am not loading near as deep as you are. Here is how I am doing it. Once I have the fire established I load nut sized to base ball sized stuff on the fire about a half of a 5 gal bucket full at a time, then leave the draft in the ash drawer full open until that load is going good then repeat the process, usually a 5 gal bucket and a half. Then throw some larger chunks on top. Maybe 3 or 4 pieces foot ball sized or a little smaller. You have to let it get going good before you shut it down for the night. There is so much volatiles in this coal I have to leave the loading door ajar a little until it gets going good . This usually takes about 20 minutes. I cut my own over the fire air inlets in my loading door. Three 2 inch holes with a swinging adjuster. I usually leave one hole open all night. I don't run the induction fan at night. I open manual air in the drawer about 2 rounds. I am sure that there are differences in our units but we are both doing the same thing with about the same coal. Don't get discouraged, there is a learning curve. This is my first year on mostly coal And I keep learning every day. Keeps getting easier.

Hey Chuck I got a couple of questions. I don't want to high jack your thread but where is place located that you are getting your coal from ? If you don't mind telling me where did they tell you it was $240 a ton. That sounds really high for Illinois coal. I can buy anthracite trucked in from Pennsylvania, off the Amish people for $280 a ton. That Indiana stuff I am using now is $53.50 a ton. It might be closer for you than southern Il depending on where you live.

You're in central IL? I believe there is another mine in Ridge Farm, IL that sells run of mine for under $60/ton. Zipdog, didn't you pay a visit there? How was the quality of the coal? IOn the South side of Chicago you can get lump and larger Eastern Ky bit (very high quality) for $200/ton picked up, whith ash, no clinkers, washed. Not sure how far it is for you. Or near Ft Wayne, IN, Hitzer sells hard coal for $235/ton picked up, $265 bagged.

Thanks for all the quick replies. Yes, it is a forced hot ait unit. I do have a draft inducer blower, but I don't use it. The only air that can go to the top of the fire is through a vent in the load door that opens automatically when the door gets too hot.

When I say the fire goes out, the flames are mostly gone. When I open the load door they immediatly flare back up. The coal continues to burn, but without many flames.

As far as how much, I would load a 5 gal bucket of big chunks over some hot coals and close the load door. Load up another bucket of mixed sizes. By now there is a lot of yellow flames on the new coal. I put in the bucket of mixed sizes, and close the load door. The whole time the ash door and MFD have been wide open. Once the flue gets up to about 400, I close the MFD to about 1:30. I let it keep going so the coals are going good, and then I would close the ash door. After about five minutes more, I put in one more bucket of mixed sizes. Total time between the first and last bucket is about 20 minutes.

I think my draft is pretty good. When I close my MFD, I can still hear the air flowing in the ash door. When I close the ash door, I can still hear the air whistle in past the adjuster on the ash door. If I close the MFD or adjuster any more the temps drop too low (usually about 200).

I am located in IL by the town of Pekin. The company was "City Coal and Ice" in Pekin that quoted me $240 ton.

Update: I tried something else last night. I put in 4-5 pieces of 3/4"plywood cut into 5x24" strips on some hot coals. Loaded in a bucket of big pieces, another 5-6 strips of the plywood, and then 2 more buckets of mixed coal sizes. The whole time of loading (10 minutes), both the MFD and ash doors where full open. As soon as it was loaded, I closed everything to theabove mentiond positions. The temp went up to about 450 after about 15 minutes and then dropped and held at 400 for about 4 hours. I repeaded the process before I went to bed. The house got warm enough to stay comfortable (70) for the night. It burned for about 4 hours again. At least in the morning I still had 2 trays of ash, but not many clinkers. Better, but not long enough burn. There is a decent pile of coals that I can spread out to start the process over again also. The starting pile is about 2 feet thick and I am left with about 2-3" of decient coals.

Thanks again for the replies.
Chuck

ron138 wrote:I believe there is another mine in Ridge Farm, IL

Just called them. They closed the mine.

Chuck

Man you are using a lot more fuel than me and getting way shorter burn times. I have a barometric damper and it helps a lot. I have to think from what you are saying, that your draft must be too strong. There is a whole bunch of heat going some place. With all the volatiles in this coal I am surprised you are not really puffing back when you close off that loading door. Try leaving the door partly open until the yellow flames start to settle down and the coal stops smoking real bad. From what you are saying, you're using about four times as much as me and I thought my place was hard to heat. I think a baro would help. That stuff in Ridge Farm was junk anyway, the only to get anything burnable was to hand pick it. There is a place in Decatur and one in Illipois called Curry coal and ice, I have not tried them yet, but they might be worth a call. What town is that blackhawk mine close to ? I live down by Charleston and the mine in Indiana is 75 miles from me.

If I leave the door open any longer the temps can get to 600+. I have had it puff back a couple times if I close it off too soon though also. The Knighthawk coal that sells to individuals is by Ava, IL. The ph# 1-618-426-3662. They also have stoker coal for $75 ton. You can buy it by the gallon pail to whatever you can haul it in.

I know the draft is plenty good, but if I turn it down, I loose the heat. It just barely smolders. The only thing I can think of is to leave the MFD full open and close the air adjuster more. I haven't done that because I figure that would just let the heat out easier instead of using it for the warm air box.

Chuck