Anthracite BTUs and stove ratings

Anthracite BTUs and stove ratings

PostBy: n3hcp On: Wed Dec 17, 2008 4:30 pm

This is sort of related to another post of mine, but, I think, different enough to warrant a separate post.

The Harman Mark II is rates at 72,000 BTU. From my web research, anthracite contains somewhere around 14,000 BTU per pound. Doing the math, that means that a Mark II running at rated capacity will consume just over 5 pounds an hour, or about 123 pounds a day! And that assumes 100% efficiency. From what I read, 65-75% is more realistic.

Does anybody actually use that much?? Running my stove at what appears to be marginally too high a temperature I was only using around 50 pounds a day. At that rate I would have been using about 2 pounds an hour for a total stove output of 28,000 BTUs!!! The stove was running a stack temp of 300* and a surface temo, on the front, above the door, of 600*

Obviously, I'm missing something here!
Last edited by n3hcp on Wed Dec 17, 2008 5:40 pm, edited 1 time in total.
n3hcp
 
Stove/Furnace Make: Harman
Stove/Furnace Model: Mark II

Re: Anthracite BTUs and stove ratings

PostBy: Freddy On: Wed Dec 17, 2008 5:38 pm

I'm just guessing, but IF you actually burned that amount you'd have put over 17 million BTUs in your house. Unless you live in a drafty barn, you'd be some kind of warm!
Freddy
 
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined

Re: Anthracite BTUs and stove ratings

PostBy: franco b On: Wed Dec 17, 2008 6:01 pm

Some years ago I noticed that German stoves seemed to have about half the BTU rating as similar sized stoves from other countries. I think they reflect a more practical rating regarding what the typical user can expect without over firing the unit. You could probably get 100,000 BTU from a stove of one cubic foot if you got it red hot. As a result I tend to cut the Btu rating in half and think of it as advertising hype.

I suspect boilers are more accurately rated.

Richard
franco b
 
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

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Re: Anthracite BTUs and stove ratings

PostBy: Gary L On: Wed Dec 17, 2008 6:43 pm

WOW, I don't know all the "Weights and Measures" but my house is 1500 Sq/Ft. and I use about a 5 gallon pailfull of nut per day. Maybe closer to a pail and a half on the really cold days.

My LR where the stove is stays between 70-80 degrees and the back BRs are always perfect for sleep at around 62-65.

When it gets super frozen and in the minus zero or below area I do hear the oil fired furnace kick on for a few minutes and send the ARABS a couple of bucks. This is the point when I shut a few doors and keep the heat where we need it.

I have no idea what a 5 gallon bucket of anthricite might weigh and I don't know how many BTUs my Russo #2 stove kicks out. I do know that at 123 pounds per day based on a 150 day coal heating season that this would be a bit over 9 tons. You must be joking or living in that very drafty barn!

Gary
Gary L
 
Hand Fed Coal Stove: Russo #1
Stove/Furnace Make: Russo

Re: Anthracite BTUs and stove ratings

PostBy: Cap On: Wed Dec 17, 2008 7:08 pm

When Harman & other manufactures rate a stove for btu's, they also take in to consideration the radiant heat given off of the steel structure itself once heated. This may add some btu's to their spec sheet? I don't think this supports your statement but I agree, 123 lbs would be quite high. I used 59lbs since yesterday not including the amount I still have cooking away, so about 50lbs used in 24hrs. 12"x12" reduced box.
Cap
 
Hand Fed Coal Boiler: Harman SF 250, domestic hot water loop, heat accumulator

Re: Anthracite BTUs and stove ratings

PostBy: grizzly2 On: Wed Dec 17, 2008 7:15 pm

Let me take a stab at this cunundrum. If your stove has the potential to produce 72,000 BTU and 5 pound of coal can produce a total of 70,000 BTU, then you need aprox. 5 pounds burning to reach your stove's potential. Suppose that same 5pounds of coal lasts for 2 hours and the next 5 pounds lasts for 2 hours etc. You would need 12 loads of coal in 24 hours X 5 pounds per load for a total of only 60 pounds per day. :lol:
grizzly2
 
Hand Fed Coal Stove: Hitzer 30 - 95
Coal Size/Type: pea and nut/ anthracite
Other Heating: Jotul #3 wood stove in garage. Oil backup in house. Electric backup in house.

Re: Anthracite BTUs and stove ratings

PostBy: franco b On: Wed Dec 17, 2008 8:15 pm

grizzly2 wrote:Let me take a stab at this cunundrum. If your stove has the potential to produce 72,000 BTU and 5 pound of coal can produce a total of 70,000 BTU, then you need aprox. 5 pounds burning to reach your stove's potential. Suppose that same 5pounds of coal lasts for 2 hours and the next 5 pounds lasts for 2 hours etc. You would need 12 loads of coal in 24 hours X 5 pounds per load for a total of only 60 pounds per day. :lol:


If you burn 60 pounds then the output is only 35,000 Btu per hour which is probably the max. practical output for this stove. The rest is Harmon hot air. And that assumes 100 percent efficiency.

Many cars can do 100 miles per hour but they will not last very long or get very good gas mileage.

If an oil burner burns 4 gallons per day to heat a house, that is 23,000 Btu per hour, again assuming 100 percent efficiency which never happens with any heating appliance except perhaps an electric space heater.

Richard
franco b
 
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Re: Anthracite BTUs and stove ratings

PostBy: BIG BEAM On: Wed Dec 17, 2008 8:27 pm

I thought they went by BTU's input when they rated most stoves.What ends up in your house is net output.You have to subtract the loss up the chimney.With an oil burner there is gross input and net output.Net output is what's available to heat your house.Kinda like your paycheck :D
DON
BIG BEAM
 
Stove/Furnace Make: USS Hot blast
Stove/Furnace Model: 1557M

Re: Anthracite BTUs and stove ratings

PostBy: Rob R. On: Wed Dec 17, 2008 9:41 pm

On cold days I can burn 100 pounds in my Hitzer stove.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Anthracite BTUs and stove ratings

PostBy: Paperboy On: Wed Dec 17, 2008 11:16 pm

Not to sound like a smart azz, but do all you guys really weigh your coal each time you fill the stove, or are you just estimating approximately how much you are using? I guess the guys who have bagged coal can come pretty close, but if you have bulk, you'd have to have a scale and tared container to really know.

I switched to coal from wood, hoping to have somewhat less work. I don't really care how much a scuttle full of coal weighs, as long as the house is warm!!

This is my first winter on coal, but I'm thinking my house is similar in size to Gary L. and my coal and oil usage (I also heat DHW with oil) will be somewhat close to his figures. I'm not really sure how the coal usage will play out. I bought 3 tons of bulk coal and started burning in early November. I may need a little more before the warm spring weather arrives.
Paperboy
 
Stove/Furnace Make: Alaska; Atlanta
Stove/Furnace Model: Kodiak; Homesteader

Re: Anthracite BTUs and stove ratings

PostBy: McKoker On: Thu Dec 18, 2008 12:51 am

Are you running on full burn 24/7? That's when you'd use 120+ lbs. My Koker is rated at 160k BTU....OUCH...that would be over 240 lbs/day if it stoked constantly. Right now, I'm using 60 lbs/day and we're in the mid 20s. The formula I was told to use was 1 ton for every 600 sq ft.(for our area).
McKoker
 
Stove/Furnace Make: Keystoker
Stove/Furnace Model: Koker 160

Re: Anthracite BTUs and stove ratings

PostBy: n3hcp On: Thu Dec 18, 2008 12:58 am

Paperboy wrote: I guess the guys who have bagged coal can come pretty close, but if you have bulk, you'd have to have a scale and tared container to really know.

Since our stove is at a seasonal cabin, it sees only limited use during the winter, mostly because of limited assess in bad weather. As a result, we buy our coal in 50# bags. So far this year we've used maybe 10 bags....not nearly as many as I would have liked to have used. :(

Oddly, the township considers dirt road with no full time residents to be a low priority :o . Go figure!! They might feel differently if they wanted to drive those roads to get to their cabin in the woods and enjoy the warm glow of a nice coal fire, a good book, and perhaps an adult beverage with no other people for at least a couple miles in any direction while the snow drifts silently to the ground...but I digress! :)
n3hcp
 
Stove/Furnace Make: Harman
Stove/Furnace Model: Mark II

Re: Anthracite BTUs and stove ratings

PostBy: gambler On: Thu Dec 18, 2008 6:21 am

Paperboy wrote:Not to sound like a smart azz, but do all you guys really weigh your coal each time you fill the stove,


I weigh every bucket full I put in my stove. And keep a written record of how much I use every day.
I used 8388 pounds last year heating my 2000sqft home to 73 degrees and did not have the gas furnace on at all.
gambler
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: Pioneer

Re: Anthracite BTUs and stove ratings

PostBy: Rob R. On: Thu Dec 18, 2008 7:45 am

Paperboy wrote:Not to sound like a smart azz, but do all you guys really weigh your coal each time you fill the stove, or are you just estimating approximately how much you are using?


My coal is in 50 lb bags, generally the least I use per day is one bag and the most is two.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Anthracite BTUs and stove ratings

PostBy: grizzly2 On: Thu Dec 18, 2008 6:17 pm

I weighed a scuttle full at 20lbs. I count the number of scuttles per day. So far I have used from one to two. Up and down just like the temps we have been getting. :)
grizzly2
 
Hand Fed Coal Stove: Hitzer 30 - 95
Coal Size/Type: pea and nut/ anthracite
Other Heating: Jotul #3 wood stove in garage. Oil backup in house. Electric backup in house.

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