Thin Coal Bed Experiment

BM-80
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Post Mon. Jan. 12, 2009 8:12 am

I've got a question for anybody who has experience with trying a "thin" coal bed:

First, for background, I've got a Hitzer 983 insert which I love. Unfortunately, being an insert, it doesn't lend itself to the installation of a baro. I've got plenty of draft. The house is 1850 sq ft, two story, very well insulated, with a centrally located staircase to the second floor. Even with temps in the single digits, I have yet to need the oil furnace.

The insert runs at "idle" more than 90 percent of the time (even in cold weather) and I'm using about 50 - 55 pounds of coal per day. I can't help but wonder if I could get by on less fuel by using a "thinner" coal bed. Before I go further, I agree with all the statements that coal likes a deep bed, and in the first few weeks of operation (thanks to this forum) I solved my "newbie" problems by shaking more and using a deep bed. I should also mention that I only "experiment" with a thin bed when I am going to be home all day (or in and out often) because a thin bed requires much more maintenance.

When I'm going to be gone for a long period, I load 'er up and set it on low and go.

But when I am home all day (for example Sunday) I can't help but wonder if, instead of having 500 pieces of properly burning coal at an "idle" setting, maybe I could get by on 250 pieces of properly burning coal. Especially, since the house is so warm everywhere

So, after the shaking etc part of stove operation, I have just spread a thin layer of coal on top of the fire, instead of throwing in a complete hod of coal. In about half an hour, the new (thin) layer is burning just fine and I find that the heat output (and fuel use) is less, but like I said earlier, I get PLENTY of heat even at idle.

Sometimes, if I throw in a lot at once, about 3 hours later I have too much heat, because eventually ALL the coal pieces in my stove are burning. I'm thinking: 250 pieces burning equals less heat (and less fuel usage) than 500 peices.

Of course, when I have tried this, I need to add coal about once every 3 or 4 hours....I need to be home and tending the fire more...

Opinions?

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coaledsweat
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Post Mon. Jan. 12, 2009 8:59 am

Going thin is looking for trouble. You will burn more coal, have outfires, cooked grates, etc. Fill it up.

PelletstoCoal
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Post Mon. Jan. 12, 2009 9:07 am

Just curious regarding the baro, is that how FP inserts are piped, I often wondered about that (space constraints)if there was a baro how would you see it, adj, it, read it..? Dose hitzer design the stove in a way which the baro is not required? I am considering a 983 for my fireplace.

frank

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baldeagle
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Post Mon. Jan. 12, 2009 10:05 am

PelletstoCoal: I have a Hitzer 503, and there is no way I am aware of to get the baro damper installed. I love my insert, we heat our 3 flr colonial until the temperatures are in lo-teens with only the insert. The ash door is slotted, there is also an arrangement within the door just below the glass if you want a little air above the fire for "the blue ladies. The stove has a bonnet thermostat and the fans kick on @ about 120F, getting the heat out of the fire to the room though a totally sealed heat exchanger (16 baffles inside w/ 2 fans moving the air through the channels), it is quiet at maximum -- our Hitzer 354 makes considerably more air noise. With the gravity fill hopper and extra low air setting we can leave Sat. am. for the wknd. and still have a fire to revive Sunday 4-6pm. We burn about 3t/year of nut ...... our gas budget (2004) from the local natural gas (Dominion)
was +$2800/yr. To return to your question, the stove is so tight we normally run with the 8 ash door slots open to just 3/8"
circles (24F here this am) living room is 73 - second floor is 67F. You use so little air that if we had a baro damper I doubt it would change anything. By the bye, @50F it is hard not to overwarm the house, come spring we will try using just one grate as suggested here on the site -- with the ability to shake only one of the independent grates I'm pretty sure that will work well.
baldeagle

CapeCoaler
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Post Mon. Jan. 12, 2009 10:50 am

If you have the draft cut back and you feel it is still sucking too much air, try some Pea sized coal to further reduce the draft on the insert.

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Ashcat
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Post Mon. Jan. 12, 2009 3:31 pm

Rather than risk losing your fire, try this instead, which I learned from someone here--I can't remember who. Load a pile of coal in the center of the firebox with 10-15 pounds of coal, carefully "stacking" it as high as possible. Then shut down the ash pan vents as far as you're comfortable. The edges of the box will burn out completely. You'll eventually (10-12 hours?)shake down all this ash, and the pile will spread out as you shake. Then, simply reload in the same fashion with the center pile. I have a lot of draft, and this has become my preferred method of idling my 983.

Dann757
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Post Mon. Jan. 12, 2009 5:10 pm

I've noticed with my 14" diameter firebox, 9" high, all the coal eventually gets burning. I've been keeping the level at or a little above the top of the firebricks. It doesn't seem like the coal could burn on the bottom and work its way up to the top through the depth of the coal bed. Or just stay burning on the bottom, have the ash created fall through the grate from shaking, and still have unburned coal on top of it. It all gets going except the top layer. Overnight, I get what seems like almost complete combustion of the pile, except the top layer, and I get bridging below. I have been knocking the bridging down, poking the ashes out, and reloading; as this makes the pile go down below the top of the firebricks. I'm not afraid to knock the bridging down anymore, as long as I maintain the air spaces by poking up through the grate holes. I don't even know if this is the best way to run this stove, but I've been going with the deep bed for a few weeks.

BM-80
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Post Tue. Jan. 13, 2009 9:57 am

I'm humbled by the results of the experiment. Results were not good.... (By the way, I'm not sure that I agree its bad for the grates....I believe that as long as the air can properly circulate under the grates that there will be no problem)

While it (thin bed) worked while I was tending it often, the next day the fire was almost out. There were lots of dead spots and plenty of unburned coal in the stove. I did a little forensic digging and the fire was NOT ash bound....just dead. I have since revived the fire and learned my lesson.

Thin bed is not a good idea.

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MountainPreacher
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Post Tue. Jan. 13, 2009 3:12 pm

Ashcat wrote:Rather than risk losing your fire, try this instead, which I learned from someone here--I can't remember who. Load a pile of coal in the center of the firebox with 10-15 pounds of coal, carefully "stacking" it as high as possible. Then shut down the ash pan vents as far as you're comfortable. The edges of the box will burn out completely. You'll eventually (10-12 hours?)shake down all this ash, and the pile will spread out as you shake. Then, simply reload in the same fashion with the center pile. I have a lot of draft, and this has become my preferred method of idling my 983.
This sounds very interesting and worth a try. Thank you for telling about this!

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Ashcat
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Post Tue. Jan. 13, 2009 8:30 pm

Mountain preacher: This sounds very interesting and worth a try. Thank you for telling about this!
No problem. None of us will be idling any time soon :) , but this works very well and cuts coal consumption. The fire slowly burns up through the pile and can be easily brought back to life with usual procedures. If you want to get a hot fire throughout the box again, after shaking down just load green coal everywhere, give it extra air, and let time work its magic to spread the fire.

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Post Tue. Jan. 13, 2009 8:57 pm

A deep bed fire with a firebox reducer or just shake one grate if possible if you need to cut back the heat and coal consumption.
The 503 insert has independent shaker grates.

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LsFarm
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Post Tue. Jan. 13, 2009 10:06 pm

Hello BM-80. The area of the fire determines the heat output of a fire, the depth of the firebed determines the duration of the fire.. I'm not surprised that you ended up with a few problems with your thin-bed experiment.. Coal is a 'social fuel' individual pieces of coal will not burn,, coal needs a 'community' of coal, each hot peice is giving and recieving heat from the adjacent pieces of coal.

If you want to reduce the heat output of your stove,, do a search on 'firebox reducer' or 'reducing firebox' there are several threades on the subject of reducing the area of a firebox so that the heat output is reduced, yet still retaining the deep bed of coal needed for long duration fires..

Hope this helps.. Greg L

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WillRockwell
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Post Tue. Jan. 13, 2009 10:13 pm

On warmer days, like in early spring, I load my Godin only half full. It burns well and creates less heat.

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Devil505
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Post Tue. Jan. 13, 2009 10:23 pm

WillRockwell wrote:On warmer days, like in early spring, I load my Godin only half full. It burns well and creates less heat.
I do the same thing since it makes clean out much easier for frequent shut downs. That being said, every "Thin" fire means you are always living right on the edge of losing your fire. As Greg says, coal is a 'social fuel & likes a deep bed to burn well, so burning THIN means you are always fighting for the fire's life! :lol: (I'm around the house most days so it's easy for me to regularly check it/ad coal or air.....If the fire will be unattended for many hours, thin fires are tough to maintain.
Last edited by Devil505 on Wed. Jan. 14, 2009 4:37 am, edited 1 time in total.

BM-80
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Post Wed. Jan. 14, 2009 2:16 am

LsFarm wrote:Hello BM-80. The area of the fire determines the heat output of a fire, the depth of the firebed determines the duration of the fire.. I'm not surprised that you ended up with a few problems with your thin-bed experiment.. Coal is a 'social fuel' individual pieces of coal will not burn,, coal needs a 'community' of coal, each hot peice is giving and recieving heat from the adjacent pieces of coal.

If you want to reduce the heat output of your stove,, do a search on 'firebox reducer' or 'reducing firebox' there are several threades on the subject of reducing the area of a firebox so that the heat output is reduced, yet still retaining the deep bed of coal needed for long duration fires..

Hope this helps.. Greg L
Hi Greg...
Yeah, it helps a lot. Firebox area reduction sounds like the way to go. Actually, if I think about it a little, the experiment was NOT a failure if the goal of the experiment was to learn something.....

Bob M

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