Harmon SF2500 Issues

A guy that works for me has one that was in his house when he bought it. He is heating 1800 square feet and goes through coal like crap through a house. He's burning nut coal. First thing I noticed is no damper of any kind on it and the manual is really vague. This thing just won't hold heat and keep up and the stove is rated up to 3200 square feet. It's fixed into his duct work. The automatic draft control is wired to a thermostat which he just changed to a digital because the old one let it drop like 8 degrees before coming on. Any help? Thanks.

Great that your willing to help out a friend. It would be much easier if he got on the forum so we could go one on one. Cuts the lag time between question, answer, result.

Rev. Larry
New Beginning Church
Ashland Pa.

He works for me so he's usually with me. He doesn't do much online do I said I'd post something up. The manual makes it sound like it needs a barometric damper but don't hand fired stoves usually use a manual one? His heat is just going out the flue and he's getting nothing from it.

Could be a variety of issues. Starting with how well ash is being evacuated all the way to excessive draft that would need to be measured by a manometer.

Can he get heat out of it if he manually controls the primary combustion air feed instead of letting the thermostat do it??

He first ran it by manually setting it with no thermostat. Pretty much the same results. As far as ash. . He keeps the grates clean and the bin empty.

if hes burning through coal like candy corns and the stove is not producing heat into the living space its a pretty safe bet his draft is like a french ..... in a brothel being paid $1k AND he has NO damper and/or functional baffle. Pictures of the stove (inside and outside and the stove pipe/chimney) would help a great deal to better help you... but the simple fact is...he is chewing through coal and he is getting nowhere near the heat he should be (the heat from that coal is going somewhere!) The good news is that its easier and cheaper to slow the draft than it is to increase it ... so based on my assumptions with no photo's we need to figure out how to tighten things up and hold that heat from flying right up the chimney.

I am currently running a Harman SF160, SF means spiral flue. So the exhaust on his stove and mine are basically if not exactly the same. Am also using a manual pipe damper (MPD) to restrict exhaust flow. The few times I experimented, and opened the MPD, I also went through coal like crazy. Your friend definitely needs either a baro damper or MPD to control draft. Along with a manometer and at least 1 carbon monoxide alarm.

Have him limit the amount of secondary air (over the fire air) as much as possible after burn off of volatiles of a fresh load.

Make sure the load door is sealing completely by doing the dollar bill test. Close a dollar bill in the door seal and see if it pulls thru without much effort.

Make sure all primary combustion air is coming in under the grate and can't be routed around the coal bed. I'm not sure if this particular fire box has air passages for routing primary air up over the fire. Routing of primary air up over the fire will hinder heat production and cause heat output to drop prematurely thru the burn cycle and lead to a dead fire.

If the above guidelines are used, it WILL produce a hot coal fire UNLESS drafting is inadequate. Draft needs measured with a manometer to determine.

Excellent post J F Graham..

I'll post some pics up soon. He has my manometer so he can check it. He already has CO detectors as well. Thanks guys.

Where the flue enters the chimney it needs to be sealed so room air can't be pulled into it.

What is that stuffed with insulation underneath?

Yeah I noticed that. That would be his clean out. That's being addressed

ALSO, Harman recommends .06 draft, at least for my boiler, should be same as units are so similar. And also recommends secondary's, Knobs on door opened 1/2 to 1 turn. I keep mine at 1/2. I also keep idle air at about 3/16" open, much more and you are wasting coal. Hope this helps
Jim

BennyLumpkin wrote:Yeah I noticed that. That would be his clean out. That's being addressed

Yes sir, all that needs sealed for adequate draft. This could be the root of the heat production issue. Weak draft equals weak heat. He should have a minimum of -.03 to -.06" water column maximum for draft. What manometer is he using? He knows how to and where to check pressure right?

Haven't found where to check it yet. We're going to work on it tonight. He's using my Baccarat brand manometer. He just said his idle air is clear open. We'll be making some major adjustments. I'm kind of ignorant to setup on this as I've always had stokers.