Questions for Haman SF/150-250 owners

Hello everyone. I'm new too the forum, and it's great too see some of your are running Harman SF150+250's.. We just upgraded our old system (ancient glenn wood) with a Harmon SF2500. I plan on using coal in her, but have been trying too get a clean burn with wood. Can anyone give me some idea of how you've set yours up when burning wood? Should I keep the ash door vent closed the whole way, or is it a little of each? Also if I get some coal before it gets much warmer, will coal harm my 317Ti flex liner in my chimney? Any help would be greatly appreciated. She seems too be a little too finicky for me too "totally" figure out...

David J, Lancaster Pa

David--

Are you using the SF-250? Not sure if there is a SF2500?
If you are burning wood, you need only use the two top door dampers. If burning coal, close off the top dampers and use the bottom damper.

Now, you can get away with wood burning using all 3 or just the top two. This is not true when burning coal.

You risk creasite buildup in your liner which will require annual cleaning. Coal will not produce creasite.

Not sure what 317Ti is but 316Ti is rated for coal, oil or gas. If it is 316 Stainless Steel your all set to burn coal.

Yes cap its a new Harman SF-2500A. I lined the chimney too try too increase draft, and keep a constant higher chimney temp for burning wood. Plus for piece of mind for fear of a chimney fire. It seemed the tile liner in the chimney was to hard too keep hot enough, and we had massive creosode issues, plus moisture (as you can see in the pic from past leakage). Coldsweat, The liner is 316Ti (my bad). Same spec as the 316, but its titanium impregnated too make it a lighterweight. It will take 1000* constant, and ULL listed (3 overheats at 2100* 1/2 hr cycles for a total of 1.5hrs) Came with a lifetime warranty too. I have it installed into a tile lined outside chimney 30' tall.

Hi DavidJinPa. It looks like your wood may have been in need of some more seasoning. The leaking creosote is telling us that the gasses/smoke/fumes going up the chimney are pretty wet/damp.

This is one of the reasons I have switched completely from wood to coal. You can slow down a coal fire, and you will never have creosote forming in your chimney or in your stove/boiler/furnace. The only byproduct of a coal fire is the fly ash, CO2, CO, and heat. A very little moisture, but there is nothing in the fumes to react with the moisture to make creostote, so it is harmless.

Coaledsweat answered your question about the air supply, the above-fire air controls for wood, maybe with a little below the fire. For coal, only use the below the fire air, shut off the top spin controls.

Make a nice deep coal fire, as deep as you can. Load it up to the top of the firebrick in the firebox. Then damp the fire down with the ash pan air control. I think you will be amazed how long the coal will burn. And the even heat output.

No more 3-4 hour feedings of more wood, it's more like 10-12 hours with coal.

Greg L

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Thanks for the reply Greg. The furnace ran like a champ last night with 90% of the air being supplied on top. It took a good bit of tinkering too get it burning satisfactory, but 8hrs later I had a 4" deep bed of nice hot coals this morning. I plan on running out for coal today too give it a try tonight. The wood I've been burning has tested at only 15% to 20% moisture on my meter. I actually have come to beleive that moisture+air was coming thru cracks in the liner that happened when we had a small stove pipe fire this past fall with the old Glennwood furnace. It inspected A'Ok, but I think its got many hairline cracks you just can't see with mirrors. Heard it cracking/popping outside myself when the stove pipes cooked out. Thats part of the reason I ran the liner, besides safety reasurance. With the new liner I've seen drastic changes for the better with burns in the furnace. It really changed the draft. I'm always adding too the learning curve, so I'm sure I'll be back too ask coal related questions today/tomm. sometime, lol. Thanks for all the help everyone...

I have heard the cracking and popping before too, [when I was burning wood] I always thought it was the glassy layer of creosote cracking from the heat. It could be expansion/contraction of the flue liner.

Most clay-lined flues will last a century or more. But if it is an outside masonry chimney, it will be harder to keep really hot to draw well.

I assume when you said you had a fire last night with 90% of the air above the fire, it was a wood fire?? Wood will burn well on a 5" deep layer of ash, many wood stoves don't have any form of grate, and require the wood ash to be shoveled off the floor of the firebox. I think wood likes the insulating layer of ash. The oxygen joins with the hot embers of the burning wood above the wood to create flames, or if not enough oxygen is present, then the unburnt gasses go up the chimney and condense on the cool chimney surfaces, creating creosote.

I have burnt VERY dry wood, it was kept in a dry shed with a greenhouse roof, so it was almost like a kiln during the summer. And the wood still created crosote. The only way to get wood to not create creosote [from my experience] is to burn it very hot, with lots of flames, to burn up all the gasses. Otherwise, creosote will condense in the chimney.

Have you inspected the chimney since those creosote stains appeared?? I'd hate to hear of a chimney fire!!

When you make your coal fire tonight, get that 4-5" layer of wood coals again, then add a 2-3" layer of nut or stove coal, open up the ashpan door vent, close the loading door vents. Let this first layer get burning, then add a second layer , still just 2-3", you want to be able to see the red fire through the newly added coal. Let it get burning as well. Then load up the firebox to the top of the firebrick. Let this get burning for 20-30 min, this will differ with different chimney draft, and stove/furnace design. But let it burn enough that you can see the small blue flames above the fresh coal.

Then close down the air under the fire to about halfway, this is a tough thing to estimate, but you want to cut back the air enough to control the heat and rate of burn, but not too little, and have the fire go out. With most Harman spinner air controls, I think 1/2 to 3/4 of a turn out from closed should be enough.

Hopefully Mark Cap and Greg White both with Harman SF models [but not your furnace] can help with the initial air setting.

Hope this helps, Let us know how it works out.

Greg L

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Thanks Greg. The chimney is a west facing exteriour, and that popping was way too intens too just be creo. It sounded like someone snapping dinner plates in half. Crazy, Weird, and Scarey!!! Well anyways, I went out yesterday, and bought some coal (Reading Coal Co anthracite). Being unsure of which size it would prefer I purchased 2 buckets of pea, and two buckets of nut. Too start of (last night at 6pm) I made a nice bed of wood coals, added about 2/3" of nut, then 1" of pea on top. after about 10/15mins most of the blue flames diminished, and she was glowing 70% red. I them proceded too add another 2" of pea, and left that cook off, and get too a 70% red glow also then closed the door with the holes open 2/3rd on the bottom. two hours later I added another 3" left it burn off until I seen the glow coming up thru some, and closed the bottom door completely (drafts still open 2/3) as I did before. Its now 9:30am the next morning shes still glowing red bed of coarse, and after shaking if down a bit I'd say I only burnt 2" of coal this far. Wow. The houses core temp stayed at 70/75*, and the kids commented about how "even" the heat felt in the house. Granted with the houses core temp at 70*, and it only being say 30* outside last night I'm sure the thermostat never kicked the draft door open. I'm totally amazed at how it performs. Wow. Also I still could have added another 5" of coal into the fired box if I wanted too. Now I just need it too get really darn cold again so I can really test it out. I think the nut alone would probub burn hotter letting more air thru ect, so I'll try that if it really gets chilly Neat stuff guys, Thanks a bunch, now I understand what you mean by the even heat thing....

David J, Lancaster Pa

In Lancaster you should be able to get good coal for a good price. You don’t have to worry about drying your wood, bugs, and chimney fires. Just stock up in the summer when it’s cheaper.

When it’s cold, like what we having coming this week you might need to switch to a 8 hour burning cycle. When you wake up, dinner time, and before you go to bed. Keeping it topped off to the firebrick is the key.

I love the hand fired thermostat on your furnace. I want to retrofit one of those on my stove. I might have to be the first one to do that here, because I’ve yet to see someone do that here. I think most of the time it would run without it (like your seeing), but my house can go from 2am @ 72 to 6 am 69, and that ticks me off everytime.

Day two. Even more amazed. Thermostat set at 72 for the night, when I gotten up @9am (No work, yes I really slept in. I'm a third shifter) it was 31* outside, and 77* inside. Still Fuel in the firebox, say 5" of coal . Now this is with a very poorly insulated (Brick) house with very dated windows. Like I said amazed. All this time say 2 months I've been fighting the wood for controlable even heat. Switched too coal, and it took 4 hrs max too get it under total 100% control. Wow... Think I'll do some calling around today, and see what a ton of the stuff going for right now, and deff stock up this summer. I'll still be burning wood when she's really cold, but cash flow permiting she's gonna be burning coal 50/75% of the time . Thanks too all, and boy am I glad I live in coal country.

DJinPa

Hey djin,where do you by your coal?I buy mine over in columbia, I think nut size is about 180 ton now.This is my first year burning coal,use to burn wood.The only way I burn wood any more is to start my stove can you pm me with that info?I dont want to step on the admins. toes I'm not shure if he delivers down here or not.

Hey tstove. I purchased some from Mellingers on long lane. It was only 6 5 gal buckets full, and it cost me 24$ I think that seemed a little steep, but I think they just sell it so they can say they do. I called around. The cheapest I found pea, and nut for was 175$p/u or 208$ for 1-2ton, and 197$ for 3 plus delivered from Mill Creak Coal on Old Philly pike very close too me. Mussers wanted 195$ a ton, and I think that was p/u only. Obviously its the wrong time too buy. I burned all the coal we had for now, but I'll be getting some when funds allow. I switched too wood today, and I can't seem too get the darn stove too stop puffing unless I have say 800* going up the pipe, and let the wood cook off about 80%. Seems too have a run away thing going on, my testers junk meaning this wood just not seasoned enough... It's been two plus weeks since I installed the liner so I guess it's time to go up too inspect, and clean too see what its doing. Things drivin me nuts. Love it with coal, and I'll be going back too it asap. DJ

Hey tstove. Finally purchsed a ton, and had it delivered. Cost was 185 from Ben Reese the closest possible dealer near me. Super convenient, and he even brought me the "range coal" (mix of pea+nut) I inquired about. Perfect timing with all the spring white stuff thats happened too. She's chugging along, and heating the house pretty well. But seems too be putting a fair amount up the chimney with 350/400 while running flat out at say 75%. Does it sound like I need a damper in the stove pipe too keep the heat in the stove, or is this normal? Anyone out their with a new'er Harman 2500A, and experience with it???

David--

Once you get to know the characteristics of your model, you will know best how hot to fire it.

For example, if I expect to see 250-300F warm air into my heat collector, I will be shooting 370-400F up the stack. But if I let the coal simmer at 175-200F, my stack temps will be around 220-250F or maybe lower. Once things settle down on my model, I will see the same temps on the hot air collector as I will see in the stack. This is the most efficient setting on my unit. But I will not be producing a great deal of btu's heat.

A damper will only allow outside air to mix into the flue in order to regulate your burn rate. A coal damper isn't really designed to *keep the heat in*. At least this is the way I understand it. A wood burner will used a wafer style damper to slow the burn rate down and hold in the heat but with coal, control your inlet air and use a barometric damper to regulate changes in the atmosphere such as ambient temps, wind & relative humidity.

hey djin, sounds like a pretty good price delivered for now. I think I have enough to last me till next season.I only bought 1500 lbs. back in november, just drove my truck up to columbia and told em to dump till it started to squat down pretty good. I only heat my work shop 2,3 sometimes 4 days a week.Sounds to me like you need some kind of damper on that stove,I know every stove and chimney combo draw diffrently but my stack temp ave. around 150 to250 when my stove is running around 400 deg. One time I made the cardinal mistake and walked away with a fresh load in,came back to 550 on the stack 850 on the stove.Fourtunatley nothing got ruined on the stove.I like burning coal(my first year) but I'm ready for summer so I can complain about how hot and humid it is