A Little Overwhelmed! New to Coal Stove (Harman SF 250)

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Joined: Fri. Jan. 24, 2014 11:27 am
Hand Fed Coal Furnace: Harman SF 250
Location: Poconos, PA

Post Sat. Jan. 25, 2014 9:09 pm

I have recently (two weeks ago) become responsible for heating my home (about 2300sq ft with cathedral ceilings) solely via the coal stove in the basement. This has been the home's only heat source for several years, but I was never responsible for it.
Anyway, I have managed to keep the fire going, even while gone for 10h or so at work, but that's about it. I don't know anything about burning efficiently or safely. I keep reading about the different temperatures, drafts, etc... and getting overwhelmed. Can I melt my stove? How do I know if I am overfiring? I know I need to search and read, which I will, but if anyone can offer some advice or words of wisdom, I will take it!!

Thanks so much!!

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Post Sat. Jan. 25, 2014 9:19 pm

Welcome helkat22, most of would like to know your where abouts for that reason you stated. You are in the right place and many with your type of appliance will be along. I know from reading others with your stove you have a nice heating machine.

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Post Sat. Jan. 25, 2014 9:25 pm

Wow, welcome aboard Bro... You've come to the right place!!
helkat22 wrote:Can I melt my stove? How do I know if I am overfiring?
Got a thermometer any where on the stove?? NEVER load it with coal and leave the ash pan door open unattended, the stove can and will reach dangerous temperatures..
helkat22 wrote:Anyway, I have managed to keep the fire going, even while gone for 10h or so at work, but that's about it.
More burn time depends on many factors, starting with how high are you loading the coal?? It should come to the top of the fire brick.. How hard are you pushing heat?? Some stoves get 24 hour burn cycles but the norm during winter is 12 hours between service times.

Feel free to ask away, many here with the same unit willing to help.. :D

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Post Sat. Jan. 25, 2014 9:31 pm

Well the short answer is yes, you could melt your stove. But it's not likley. One of the worse things you could do would be to leave the ash door open and forget about it. That would feed lots of air to the fire and your stove would go all "fukashima reactor" on you. :shock:

If you could describe your setup alittle, that would be helpful. Describe the location and chimney type. Is there a barometric damper? What size coal are you burning? Photos of the stove and vent pipe would be helpful. That is a beast of a stove. I believe its rated for 120K btu's.


You need to do a thorough job when shaking down the ash. Watch for live embers to start dropping through the grates in an area the size of the grate. Too little shaking down and you restrict the air with ash. Too much and you might dump your fire. Harman grates travel much further then needed when you operate the handle fully from front to back and you can literally dump your fire. Use short choppy strokes, not the full travel of the handle.

The size coal you burn may require adjusting how much air you supply to the coal. Smaller sizes require more air. Several guys here burn or have burned that stove and will chime in when they see you post.

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Post Sat. Jan. 25, 2014 9:43 pm

Thanks for the replies thus far!! First off, I am not a Bro! A Sis, maybe, but definitely not a Bro!!

I don't have CO alarms or a thermometer anywhere on the stove. The only time I leave the ash door open is when the fire has burned down to nothing and I am trying to restart it...but I really keep an eye on it. I use nut coal and always try to keep it up to the top of the bricks. I also shake pretty frequently until I see hot embers drop down. I have learned my lesson about not shaking enough.

The house got down to 56 one day when I was at work last week and has been hanging around 62. I am now back up to a more comfortable 68. I am worried about next week's upcoming cold snap and may take Tues or Wed off of work for no other reason than to keep an eye on the fire. The house really has no registers so circulation is an issue, unfortunately :( I don't know anything about dampers...sorry. I can take pics, though :)

I know I can get the hang of this, but fire really intimidates me.

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Post Sat. Jan. 25, 2014 9:50 pm

Welcome to the forum.
Sounds like you are well on the way to mastering that stove.
But it is very important to have a working carbon monoxide detector in the house, it could save your life! Please get one tomorrow!
Carbon Monoxide Detector SAFETY WARNING

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Post Sat. Jan. 25, 2014 10:05 pm

Welcome to the forum sis!! pics of your stove install w/ flue pipe please, it will make it easier to answer questions.

You've done well to keep the fire going like you have over the last couple weeks. As already mentioned get the CO monitor. Also get a temp gauge, a magnetic one that you can put on the stove and then on the flue pipe will do the job.

Keep loading it up as full as you can and control the burn rate and heat output by limiting the combustion air coming up through the grates. As mentioned shake it down vigorously enough to clear the ash and stop when you see some embers dropping across the entire grate area. Those are the basics. Adjustments after that are geared toward getting more efficient with the burn and extending burn times.

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Post Sat. Jan. 25, 2014 10:25 pm

Alright,HK22,let's get a few things straightened out for you right from the get-go! You have definitely come to the right place. We're here to help you. We have quite a few Ladies onboard,whether Members,Newbie's(Brand New To Coal and The Board) and undoubtedly a vast Array of Females Lurking in without signing up as You did. Thanx for Trusting Us and Coming On Board! I might as well tell you that it seems to me that we're Fresh Out of Internet Psychos,Ax Murderers and the Usual,Creepy Stalkers! We ask for an approximate Geographic Location just to get an idea of how cold it gets where you're at,and how long your heating season can go for. Temperature Extremes,Prevalent Wind Conditions all can come into play. We ask about your Home-Insulation,Do you have a Masonry Chimney,A Stainless Steel Insulated Pipe Chimney or even a PowerVenter in Place of any Chimney. We try not to take too much for granted. Hopefully with a Hand-fed Stove,your using one of the first two choices. You've done Damn Well to keep your stove going on your own for the last two weeks alone. We don't pry. You don't need to tell us how you ended up alone on this deal. You taking pics of the stove showing how the black pipe travels to what you're using for chimney will be helpful,as well as some general shots from around the stove won't hurt. If you can,maybe an outside shot of your chimney wouldn't hurt either. Once this starts,prepare yourself to learn well! We've got Folks that have your unit,and the rest of us,like me,help out in the spots where we can. relax,Absorb,Answer questions to the best of Your Ability and Always get back to us. We'll ask about how much Coal you've got left,and where to go when you need more. We'll also try to keep you from going broke. Hell,you might be there as I type. No problem-Your with us now. :up: P.S.-We'll need to have you find some cash for a CO Monitor or two and some magnetic stove thermometers(One on your outlet pipe to chimney,and one on your upper stove body)

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Hand Fed Coal Furnace: Harman SF 250
Location: Poconos, PA

Post Sat. Jan. 25, 2014 11:28 pm

I really can't thank you enough for the very welcoming replies! I am now going to attempt to attach pics :) Pardon the coal-y mess!! BTW, I just had 2 ton delivered today. I will probably blow through it way faster than I should, but I'm just happy to be fully stocked at the moment!
Last edited by helkat22 on Sat. Apr. 01, 2017 6:51 am, edited 2 times in total.
Reason: Fixed pictures.

Posts: 25
Joined: Fri. Jan. 24, 2014 11:27 am
Hand Fed Coal Furnace: Harman SF 250
Location: Poconos, PA

Post Sat. Jan. 25, 2014 11:32 pm

Ugh! Sorry they're sideways :( I live in the Poconos, BTW. I did edit my profile to reflect that, but maybe it hasn't appeared yet!

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Post Sat. Jan. 25, 2014 11:43 pm


There's many videos on youtube for tending coal in a hand fired stove.
I'd recommend - if you have the time - to watch a few.
Even watching yt videos from wsherrick (on the forum) and his antique stove will give you great insight into the tending of the stoves.
And I've seen some sf250 videos as well - but perhaps not as well done as some others I've seen.

If you could spare the cash...I'd pickup some $15 stove thermometers and stick one on the stove top and other on the black stove pipe.
It's like monitoring the pulse of a patient. I wouldn't want to try and maintain a coal stove without knowing the temps of both stove and pipe.

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Post Sun. Jan. 26, 2014 1:39 am

I don't know the finer details of your particular stove model, but if the fire is a little less in one part of the stove than in other parts, like 4 corners or just in the far back you may need to work in those specific areas for knocking down the ash better.
If you have a tool w/ an "L" shape you can work it from underneath up through grate to knock it down. It will burn better if the air can get through w/o ash blocking the air in those areas that burn slower than the rest.
If it is too difficult to poke from under grate then you make try gently to poke those trouble spots with a straight poker from above.
Try not to disturb the coal too much from above, just enough to have the loose ash drop out into the ash pan.

You can get some extra coal in the stove when needed by mounding it up in the center of the stove as much as possible...it does settle on it's own as it burns some.

Hope this helps...practice this and see if you might get to a point where you feel comfortable enough to not have to miss work latter on in order to be home and maintain the stove all day. :)

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Post Sun. Jan. 26, 2014 3:24 am

Hi, welcome to the Forum,

Don't worry - the people here will soon provide the knowledge you need to be able to burn a coal stove for maximum heat and lowest cost. I agree get some magnetic thermometers and put one on the front of your load door, I don't know for sure but I bet your model has a false ceiling or baffle and a thermometer placed on the top will give you false reading. Put the other one on the black exit pipe about 18 inches or 2 ft away from the stove. These will tell you how the stove is burning; for a while, as you learn how to burn a coal stove for less money, the temperatures will be about the same. That's because a lot of your heat is going out the black pipe. We'll fix that later. Personally, I have thermometers in every room I'm trying to heat to see what temperatures the stove is producing there. If that's lower or higher then I'd like I can adjust the Air Control Valve (ACV) accordingly. And do get a CO monitor or two if you don't have them already.

To make it simple, if your fire is burning out at before 12 hours or so you probably have the ACV open too wide. What are the room temperatures like? Do you have to wear shorts and t-shirts and have the windows open? The heat production and length of burn in a coal stove is controlled by the air entering via the ACV on the ashpan door and being drawn through the coal bed. It burns from the bottom up. How open the ACV is determines how hot the fire will be. Close it and the stove will burn cooler and longer. I have the Mark II and I rarely have to have the ACV open more then 1 turn but I live way south of you. You will have to fool with the ACV to determine where to set it to reach the heat production your want for your space. Learning how to control your heat production is the first step. Oh yeah, don't think that you have to have a rip roaring fire with the "blue ladies" (flames) dancing. As long as your stove front thermometer is registering a temperature your fire is producing heat. It will burn as long as you provide air and fuel so fill it up to the top of the fire bricks with coal. In my opinion, this all you need to know right now. Controlling the heat production to get long burns that produce the heat you want is the first step. Remember a coal fire changes degrees very slowly, it takes a while to heat up and slow down. Be patient as you play with your ACV.

After that we can show you how to maximize the heat, get it distributed throughout the house and do so for the least cost. Believe me, you came to the right place and it will all fall into place in a couple of days.

I read above that Coalkirk told you to shake the grates until you see the first red embers falling into the ashpan. He's right, that's how long you generally shake your stove. However, how do you do that with the door closed so you don't release a ton of fly ash into your living space? I look for the glow around the ACV. When it's glowing bright red, I'm done shaking. I'm also done shaking if I meet resistance to the shaking from unburned coal. If that happens I stop shaking and come back later. In most cases the blockage will burn up and be gone when I come back. You should plan on shaking your stove every 12 hours or so. It can slide a few hours either way if needed.

Don't worry, all this will feel into place and in no time you will be enjoying the low cost warmth and ambience of the coal fire. Lisa

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Post Sun. Jan. 26, 2014 3:53 am

Helkat22, you already recieved great advice. Only thing I would like to add is don't let the fire intimidate you. A coal fire is alot safer than a wood fire. Just be mindful of the draft and amount of air. You'll get the hang of it. You have a good stove. I'm working longer days than before so my wife had to take over some of the tending. At first I was coming home to almost dead fires, now I come home to a warm house and a healthy fire. Welcome to the forum. Matt

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Post Sun. Jan. 26, 2014 4:36 am

welcome to the forums...

#1 It would be very hard to meld a Harman stove (if you loaded it... then left the bottom door open... you would likely see some of those 1/4" walls/top plate buckle or warp and get cherry red... but not melt).
#2 If thats your basement than you have one nice fireplace set up in your basement! so let do some serious cartwheels for that alone! :clap:
#3 do you have a blocker plate of some sort sealing the area around where that stove pipe goes through the damper opening in that fireplace? (if not... do it by reading threads about blocker plate options)
#4 I notice that fan on the floor right in front of the stove (this is a VERY fine line to walk because you could be introducing a forced air draft into your stove with that)... this would make your burn times MUCH less and the stove MUCH hotter and a lot of MUCH wasted fuel. (that stove NEEDS a proper working blower on it... if you don't have one....get one!) be very careful how if using that floor fan the direction its facing (at stove will produce a forced draft, away from stove could effect suction from the primary draft) and how you use it, typically id rather see a smaller metal fan way back in the fireplace facing out (if space allows)
#5 the most common problem I see with the Harman (or even on my Crane 404 and many others)... is getting a complete shake down and complete load up! one this stove your likely going to need to play the poke N scrape game (shake it good for a minute, then open bottom door and scrape under the grates, then poke through top door to "settle" the coal bed more, then shake again... then leave bottom open for a min or two to get a nice hot fire... then load it up heaping and as evenly as possible across the entire coal bed... then leave the bottom door open another couple minutes to help burn off volatiles and not loose temps to drastically... then close it down, adjust primary draft knobs/mpd and let her ride for 12-24 hours depending on temps outside (when its 0 degrees none of us are going 24 hour cycles... 12 hour cycles is normal).
#6 I don't see a MPD or a Baro (I know Harman is hellbent that their stoves for some magical reason don't ever need a Baro or MPD in the stove pipe.... THEY ARE WRONG... these are items that are part and parcel to good, true, expert coal burners! learn about them... understand them... utilize them to your benefit!
#7 you can learn to keep that dust/mess to a minimum by searching "reducing ash mess dust" or here is one regarding Harman dust in particular Ohhh the Dust!!!
#8 Everyone knows I don't particularly like Harman (my own personal issues)... but if I had a Harmon... yours would be the model Id have! :up: best wishes to you and we all hope you stay on board with us here as a friend and fellow coal queen!

P.S. you can use the search area at the upper right of screen to search & learn about anything regarding coal burning, coal stoves, YOUR stove, etc... type in "Baro or MPD", "Harman SF 250", "Longer burn times", etc.etc.etc... you can learn for years here and still not know everything (like me toothy )

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