What Temperature Is a Coal Fire?

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Cap
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Post Mon. Jan. 09, 2006 8:40 pm

Hello List--

Who would know at what temperature a coal fire burns? And what temperature would you expect inside the firebox above the hot coals?

Inquiring minds need to know!


lime4x4
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Post Mon. Jan. 09, 2006 8:46 pm

I was always told coal ignites around 900 degrees farenheit.
So I would guess around 900 to possible 1200 degrees around the fire box in the area directly next to the burning coals.
I have a laser temp gun that's good to 1000 degrees if I try to take temp reading of burning bed of coal it goes to out of range

bjs1779
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Post Tue. Jan. 10, 2006 12:15 pm

I have seen anywhere between 2000 to 3000 F depending on draft. Blacksmiths can weld iron together at those temps. I've got a coal radiant stove and it's nothing to get the flu temp over 1200 degrees with the ash door cracked open a bit. How hot will it get? I don't know, but I believe the lady that said her stove's top sagged when she forgot to close her ash door!

I usually maintain 900 to 1000 F with it for heavy heating. I don't have a surface thermometer - yet.

Dick

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davemich
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Post Tue. Jan. 10, 2006 1:45 pm

1200 degree flue temps?? Wow! I have an insert so I don't know what the stack temp is but my stove surface temp is rarely above 500 to 600 degrees. And if I am correct, the stack temp is usually lower than the stove top temp meaning that my stack temp probobly is about 50 to 100 degrees lower. This is more than enough to warm my 1800 SF home. I would be really curious to see what your stove top temp is. The magnetic thermometers are about $10.

bjs1779
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Post Tue. Jan. 10, 2006 2:49 pm

I just laid my flu gauge across the top and it read 750 @ 900 flu temp. Got to have it for 3500 sq. ft. It is odd to me why the sides of this stove gets hotter than the top of it though. I know this to be true because the first place that the black paint starts to turn a little white is along the sides. I can't stand there long enough to measure it though without setting my clothes on fire : ) I will get one of those magnetic thermometers in a few days.

Dick

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davemich
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Post Tue. Jan. 10, 2006 3:12 pm

BJ...what kind of stove do you have? I agree...you would need to generate a lot of heat for 3000 SF plus! Are you using anything else or does the stove heat the entire house?

bjs1779
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Post Tue. Jan. 10, 2006 3:41 pm

It's an Englander that I got off of Ebay awhile back. It heats my place of business pretty cheap I must say. Gas bill was 16.69 for December here in Illinois : ) I'd be looking at 800 to a grand if I didn't have it. So far, I only have to burn it durning the day and I may have used about 1 1/2 tons of 180.00 dollar per ton of coal since October 14th.

It gets a little cool in here overnight. About 47 was the lowest I've seen it at zero degree weather, but with the draft of a 50 ft chimney I can get it going hard in less than 5 minutes and feel heat.

Dick

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davemich
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Post Tue. Jan. 10, 2006 4:23 pm

BJ, where in Il. are you?? And where are you getting your coal from? You can email me your answer as I believe this is not the place CoalMan wnats this info to be discussed. Thanks...Dave


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Cap
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Hand Fed Coal Stove: Harman SF 250, domestic hot water loop, heat accumulator
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Post Tue. Jan. 10, 2006 8:43 pm

The reason why I ask...I may consider installing a ss bimetal thermometer into the firebox. I've been looking for one on ebay. I missed a 100-800F this past week by .50cents.

My plan will be to tap a 1/4" f npt thread into the side of the firebox as high as possible near the rear behind the shaker lever. Screw a Parker SS 1/4m npt x 1/2 f npt adapter. From there I can screw the ss bimetal thermometer into the adapter. I will apply the same idea to the flue pipe. I already tapped the firebox with no trouble. My adapter screws in nicely.

Yea, I know, a little modern for a basic handfired Harman unit but I work with high pressure fittings and cryogenic fluids my whole adult life, so very basic for me. This will allow the operator ( me! ) to monitor the condition of the fire and learn exactly how to control it with max efficency. I will need to find a 1200 F. max ss bimetal, if one exists. If it doesn't work out, can easily plug the tapped thread with a ss pipe fitting plug.

coalburner
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Post Tue. Jan. 10, 2006 10:03 pm

At those temps you need a pyrometric cone to guage the heat range

smiths use blast air to raise the heat in their burnpots that high.

wg_bent
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Post Thu. Jan. 12, 2006 4:44 pm

This is terrible that I don't remember this...but, what temp does cast iron begin to glow at? I remember a stove having a slight deep cherry red glow once or twice when I was a kid.

bjs1779
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Post Thu. Jan. 12, 2006 9:32 pm

wg_bent wrote:This is terrible that I don't remember this...but, what temp does cast iron begin to glow at? I remember a stove having a slight deep cherry red glow once or twice when I was a kid.
Just guessing from various forms of silver soldering I've done, it would be somewhere in the range of 1200 degrees.

Dick

coalburner
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Post Thu. Jan. 12, 2006 11:21 pm

using coal I can get my kiln to a cone 10
that is around 2350 - 2400 degrees with no problems.
takes about 5 hours to do it right.
That temp turns most glass to a water like state.

all of thsi info can be found on google

nedge2k
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Post Sun. May. 29, 2011 9:20 pm

Sorry to drag up an old topic but can anyone tell me the approx. temp of an open coal fireplace?

My gf's parents have an old (and cold) cottage with a large iron fireplace (grate?) in the living room which seems to cost them a fortune to run over the winter but they have no other heating source in that room. Anyway, my plan is to make them a heat exchanger / manifold to sit under the coals connected to a blower of some description to make the most of it but I worry the temps could melt the stainless steel tubing I plan to use and start spitting out molten metal!

Am I worrying over nothing?

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lowfog01
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Post Mon. May. 30, 2011 7:13 am

nedge2k wrote:Sorry to drag up an old topic but can anyone tell me the approx. temp of an open coal fireplace?

My gf's parents have an old (and cold) cottage with a large iron fireplace (grate?) in the living room which seems to cost them a fortune to run over the winter but they have no other heating source in that room. Anyway, my plan is to make them a heat exchanger / manifold to sit under the coals connected to a blower of some description to make the most of it but I worry the temps could melt the stainless steel tubing I plan to use and start spitting out molten metal!

Am I worrying over nothing?
Why not look for a coal burning stove or insert on craigslist or ebay instead? Those puppies can heat entire houses and there is virtually no waste of heat. Sometimes you can pick them up for virtually a song. Modifying the chimney is relatively easy. If you can create a heat exchanger you can do that. Just a thought. Lisa


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