Harman sf 250... experienced users

New here, Just joined today.
Can anyone guide me to some users of the Harman sf 250 ?
I've got some general/specific questions.
I have had this unit for a few years.

Appreciate the help,
Mossy Beard

Question number one is??

Hi Mossy Beard, I am a Harman dealer and I have to say you own one of the best coal burning stoves that Harman makes. The SF250 is a work horse that can be connected into your central heat system. So ask away.

Questions :
What is the best size coal for performance and burn duration ?
I've used nut in the past with 'mixed results". I thought I may try pea ? The nut did ok but my experience was only about 8 or 9 hrs. of productive heat.
Should I be using a barometric damper ?
What "breech and over fire draft" should I see ?

I've flirted with the idea of getting a stoker stove. My Harman is in great shape but I'd like not to get all my excercise up and down the basement steps ....
Also, wondering if the thing is going to be out if I'm a little late getting home from work

Thanks, Mossy Beard

Hello Mossy, you will get a hotter fire with nut coal, and maybe a bit shorter duration fire.. Pea burns with a bit less maximum heat but should burn longer.. The reason is that with the larger pieces with nut coal, the air passageways through the coal bed are less restricted, and more air flow means more heat..

Some folks burn a mix of nut and pea.. they keep a hot fire for the evening with nut, then cover the nut with a layer for Pea for the night, slowing down the air flow burn rate.

I would say that with your chimney, you MUST use a barometric damper.. Harman recommends it, it has been proven by many members on the forum to cut heat loss up the chimney, provide even consistant heat output, and provide much longer burn times...

Read the many threads about barometric dampers,, this will help.. The draft for most handfeed stoves should be around .04-.07" in the fluepipe, above the stove, but below the damper..

Greg L.

Hello Mossy, as Greg suggested, I would highly recommend a barometric damper on your stove.

Last winter I was using an "Estate Heatrola" stove with nut coal, the stove would hold 80 lbs of nut but I struggled to get burns past 8 hours. The stove was connected to a 35' chimney up through the center of the house, the draft was very strong and made it difficult to regulate the burn. I hooked up a baro. and got it roughly adjusted and immediately noticed improved heat output and longer burns. Once I got the hang of it I could achieve 12 hours between reloads and only used about 80-90 lbs per day.

One more thing, have to you tried coal from different companies? Bad coal can make using any stove a challange.

All good tips.
The stove is on a 30' chimney. It's been since '95 that i set the stove up. 'Only a guess that I checked draft at that time.
I completed construction on my house late summer of that year and really had not installed the central heat, that's why I put the Harman in.
I fired it for about 2.5 years until installing an oil boiler. The stove has had little use/no since fall of '98. During that time , I burned both coal and wood. I know I'll never cut wood again (30 yrs. of that....) That's why I thought about a stoker but my hand fired isn't costing me anything either.
When I was using coal, I would try to get Reading when possible.
I'm sure with some experienced "counseling", I can get it better. ( firing rate, adjustments, etc)

Thx, Mossy

As the other guy's said, I would say you need a barometric damper, one way to tell is to check the draft with a manometer. I only burn nut in my stove and i have no problems getting a 12 hour burn with out touching the stove. I've left it go for 16 to 17 hours (worked late) and it would still be burning nice, i just opened the ash door for a couple minutes to wake the fire up before shakeing it down and filling it up again. You should be filling the fire box up as much as you can when you load it. I go up to top of the fire brick and even bank it a little higher most of the time,it will hold about 85lb of nut.