How to Increase Effeciency

Modern and vintage hand fired coal stove are similar to a wood stove and in some cases can burn either. They need to be regulated and fed by hand usually every 12 to 24 hours depending on your usage. They require no power to operate making them ideal for rural settings with long power outages.
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Wayne D
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Stove/Furnace Make: Harman
Stove/Furnace Model: Mark II

Post Fri. Nov. 28, 2008 3:13 pm

Hi guys. Im New to coal burning. After reading many informative posts, it seems I need a damper. I think I am burning too much coal. Its been averaging in the 30's and uses a little over a bag a day. Im concerned that in frigid temps that will double...or more. I am worried it wont even keep the house warm either. My chimney thermometer is about 2 feet up the pipe and Its never been above 200 even with a full stove of hot coals. The 2000 Sq Ft house is warm though, so far. I turn the inlet draft control out 1 turn at night and while at work(16 hrs), and 2 turns while at home. It seems like a lot of coal to me. If I install the damper, will I get longer, hotter burns? Is there any other way to get the most out of the Mark II? Do those heat reclaimers work? Thanx.

franco b
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Post Fri. Nov. 28, 2008 6:35 pm

You need efficiency in the house as well as in the stove. Is yours old or new? Good insulation and tight windows etc.

Stack temperatures serve two purposes: to establish draft, and to stay above the temperature at which acids in the flue gas condense out. A rule of thumb is 400 degrees at the stove measured with a thermometer inserted into the stack pipe, not on the surface. If memory serves me I think the point that acid condenses is about 250 degrees, but this is at the top of the chimney. So to keep the whole thing warm enough you need about 400 degrees at the stove. This is why a small stove requires a small diameter chimney. If your temperatures are above this then a heat reclaiming device would help. Bear in mind that it will also effect draft negatively and is a pain to clean and also uses electricity. I would never use one.

I don't have a Harman stove but they seem to be well regarded by the users on this forum. By reading the many posts you may find some helpful suggestions. I assume you have a draft regulator installed.


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Post Fri. Nov. 28, 2008 9:27 pm

Using a bag of coal per day to heat 2000 sqft. with 30 degree temps. This quantity seams normal to me, that is apx. what I burn.

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Post Fri. Nov. 28, 2008 9:50 pm

I would definitely get a damper. I had a heck of a time with my Mk I before I got one. I have a hand damper even though that's not preferred. Get a baro and set it right with a manometer. You will be thankful you did. Granted, I only have a Mk I, but even running hot, I don't use 50lbs a day. 10lbs idling and 20-40 if I really crank it up.

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Post Fri. Nov. 28, 2008 10:14 pm

Wayne D wrote:i need a damper. I think I am burning too much coal.
Yes, you do need a barometric damper.

What does the bag of coal weigh? 40,50 or 100 pounds? If the first two, I would say you're doing pretty good. If the latter, you may have a problem.
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Post Sat. Nov. 29, 2008 7:25 am

As previously said, get a baro and set it with a manometer. Burning 50# a day to heat a 2,000 sq. ft. house sounds about right.
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Burning rice coal in a 1981 EFM DF520, nut coal in a hand fired Jotul 507.

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Wayne D
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Stove/Furnace Make: Harman
Stove/Furnace Model: Mark II

Post Sun. Nov. 30, 2008 6:46 pm

Thanx for the responses guys. yes, 40 pond bags. Id say moderately insulated. Good windows and about half the house could be better insulated. A baro is coming soon. I know this is contraversial, but I did install a manual damper today about 3 feet up the pipe(to allow room for the baro.) I figure once its installed I wont use the manual But thought I needed something til then. Ill keep reading posts to leard more.

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Post Sun. Nov. 30, 2008 8:28 pm

If you have a manual damper installed with a Barometric damper,, the Manual Damper MUST be below or before the barometric damper.. Otherwise you are forcing a leak out the baro damper.. You must have NO restrictions above the baro damper.

Greg L
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Post Thu. Dec. 04, 2008 11:17 am

Wayne, It is only my opinion but loose the manual damper. Modern or well designed coal stoves will not have nor recomend the use of one. A good stove will control the burn rate by air intake alone, if a stove needs a manual damper to control the burn then I would question its safety in a home. As for the baro damper, I use them as a cheap over fire safe guard due to wind or air inlet malefunction. Your Mark series stove is a very good "coal burner" and does not need a manual damper. Just my opinion :D
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