Need Help Burning Coal in a Harman SF 260

Hey Bob, very glad to hear about the progress you are making.

KTM250 wrote:My only concern is it seems like the zones run longer

I'm not a boiler tech. but I don't think you need to be concerned with how long the circ's. run as the coal boiler is putting out heat 24/7. If they run a long time without dropping the water temp too much, that should be considered meeting the goal. I would say congrats is in order. - Jeff

Don't worry about how long the zones run as long as the rooms are comfortable. It wouldn't matter if they ran constantly as long as the comfort level is there and the boiler is giving you the burn times you require. This ain't an oil burner! I think it sounds like you are moving real close to that sweet spot of performance and comfort. Glad you didn't bail.

When outdoor temp is in 30's, I set my boiler temp to 140*, and water circulates mostly by gravity, when temp drops below 30* I bump my boiler temp to 150*. 25* and colder outdoor, circulator runs constant. If outdoor temp is 10*-12*, oil boiler kicks on now and then.
I tried bumping coal boiler to 160*, but I burn too much coal for my liking. There isn't a "set" or "constant" procedure for hand-firing, (too many variables) draft changes daily with the weather, which is why it's nice to have a manometer. If it's going to be 30's and raining for a couple days, you may want to adjust your baro, etc. but, that's "fine tuning". Concentrating on the basics, and have the system operating is what's important right now. Glad you have HEAT! "I've had it with this piece of junk", "I bought a coal hog", "anybody want to buy a boiler?", etc. seems funny now. Doesn't it? You'll enjoy your "man toy".

Hi KTM, I have a Harman SF-260 boiler. I had experiences like you at first. How did you get to 12+/- hours? I can get 12+ if outside temps are over 30 degrees. I have the DHW coil that preheats water for my electric water heater. The water heater does not draw electric all winter. When it gets into the teens outside, 8-10 hours per fill is normal for me (totaling 3-4 5 gal buckets of nut anthracite a day). I'm heating 2500 sf, 2 stories, with moderate insulation in the walls and roof and multipane windows. I set my aquastat at 160 degrees with a 10 degree offset and a 30 degree overshoot (the controller won't dump heat until the water temp goes over 190). I adjust my baro damper frequently to keep stack temp near 200 12" before the baro. My biggest problems were: the initial overshoot was too low and caused a near constant "dump" of heat to the house. And I didn't shake properly resulting in a thick layer of slag/clinkers on the grates taking up room and reducing capacity and by extension burn time. If the fire goes out, I use that as an opportunity to dump the entire grate and vac out the ash from the firebox & flue using a shopvac with extra fine "drywall" bags. Doing this once a month keeps the boiler happy.

NOPEC Looking at your setup and settings, they are very close to mine. I am heating 2400 sq/ft and my hot water but I don’t have a dhw coil but a external tank run as one of my zones. My temp is set to 160 and my dump temp is like yours 190. My dampener I set to .04-.05 and I leave it alone. I checked my stack temp the other night (temps in the upper 20s) with the flapper closed and I got 140. Still had a .03 draft. Im sure that when things warm up I will have to adjust my idle adjuster (set at about 3/16 open) to maintain a good draft. This is one of the reasons why I am going to try a fire box reducer.
Two of biggest things that have help me get longer burn times are like you said keeping the bed cleaned out and when I get done shaking there is a nice glow on the bottom of the bed. I think before besides not getting enough air to make the coal burn well, the ash was absorbing some of the heat rather then letting it get transferred to the stove body. The other thing I did was slow the flows down. Not sure what kind of circulator you are using but now that I slowed the flows down my boiler temp doesn’t drop like a stone when one of the zones call for heat. This keeps you from having the flapper open and use more coal up getting the temp back up. Also would help prevent overshoots. Which as you know is just wasted energy.
I could be all wet here with my theory’s but things are working well now and even when the temps are in the upper single digits low teens I can get 12 hours out of her. I will continue to tweek it and try to get the coal consumstion down as far as I can.

Bob

KTM250 wrote:Hello all, I am about at my wits end with this Harman SF 260 boiler. It has been a nightmare from day one from installing the chimney to getting it plumbed in. Now I am struggling to get long burn times to keeping the water up to temp. I am also trying to heat my domestic hot water (with an external hydo stor tank) and that looks like it is not going to work well at all. I have tried all kinds of different settings from draft , to air flow controls on the ash pan door and shaking the bed differently. Not sure what is going on here but all I can say is that hand fired coal stoves suck. I have been using a stoker for about 8 years and never had problems. I was hoping that maybe there are some SF 260, 160 or 360 owners out there that may be able to help me. I do know that if I would have started burning coal with this unit I would have stopped a long time ago.
Thanks Bob

What a difference a couple weeks can make. I didn't repost this to embarrass Bob but to show what subtle changes in procedures and settings can make. He was ready to scrap the whole thing and give up. With help and encouragement from fellow forum members, he's got that sf250 running like a swiss watch now. Another NEPA Crossroads success story! By this time next season, he'll have that thing sippin' coal.

I'll try tweaking the ball valve on the output side of the pump. Right now, it's half open. The circulator is a relic from the oil boiler I replaced. My water temp will drop 20-30 degrees instantly when the circulator kicks on and on the super cold days, it takes a long, long, time to catch up. overall, I've been very happy with my sf-260. my only real, legitimate, complaints are that the ash pan is too small both in overall capacity and in width there's 1" on either side where the ashes aren't caught and the firebricks should be aligned vertically to allow a deeper coal bed.

efo141 wrote:Fill it so the coal just about falls out the loading door and higher towards the back of the stove. A friend of mine has the same boiler. He also had to run more than .05 of draft so the boiler would keep up with the demand. He has since mounted a 60 cfm combustion blower on the clean out door and runs only about .03-.04 with lower stack temps and keep up with the demand great.

Here are a couple pics of his sf260 setup

I especially like the chain saw stored right next to it. Yikes, hope the fuel cap doesn't leak.

I was there last night and never noticed the saw until I look at the pics. I hope it's out of gas at least.

Off topic ... but if you store it outside in the cold (in shed), there's less chance of the crappy fuel we have now turning to jelly in the carb.

EFO Thanks for the pictures. Couple of questions. I assume that the blower works just like the flapper on the door did, when the boiler temp drops below set point it kicks the blower on? Does he have a lot of over shoots where it has to move the water out of the boiler? Does he have any idea on coal consumption compared to last year? Looking at the second pic, that is really stuffing it. Looks like he almost has the exhaust at the back of the boiler blocked. I will be very interested in hearing about his coal consumption. I have my system working pretty well but still would like to reduce the coal consumption.
Thanks
Bob

CoalKirk Just wanted to thank you for opening up old wounds

KTM250 wrote:I assume that the blower works just like the flapper on the door did, when the boiler temp drops below set point it kicks the blower on

Right, He just wired to the blower after removing the damper motor and drilled the flap with a hole saw.
No, he has no problem with overshoot.
He says he is burning less with the the new set up.
He does stuff the boiler with coal. He shovels towards the back then he rakes it down to the door. Says it runs best that way.
The exhaust is not blocked, but he does fill it up.
I think he almost has to save on coal with the draft and stack temp lower. He also has less clinkers with his Superior Coal this year.

EFO One more question. Is there any problem or concerns about what happens when the power goes out? With the original setup you would still have a draft going through the idle holes. With this setup you would have no air flow. So where is the coal gas going to go? Maybe I am looking at this wrong.
Thanks
Bob

KTM250 wrote:CoalKirk Just wanted to thank you for opening up old wounds

Sorry Bob. You were just such a turn around success story that for the good of the group, I wanted to highlight your case. At one point, you had to practically be talked down off of the roof.