Need internal length and width dimensions for your firebox

Re: Need internal length and width dimensions for your firebox

PostBy: Lightning On: Fri Jan 03, 2014 9:08 pm

lsayre wrote:Where does the majority of the coal burn at? How about 2" down from the top of the 'V' sloped firebricks?

Sorry to complicate things.. :oops: :lol:
Sometimes I run it at top of the bricks level, sometimes I mound it high in the center (about 2 inches higher than the top of the bricks), sometimes I run it 1 or 2 inches under the top of the bricks. It depends on the burn time I need to get. Like tonight for example, at 6:00pm I shook and loaded about 2 inches under the top of the bricks since its going to be 9 hours till I shake and load again at 3:00am before work. Then at 3:00am I'll mound it up high in the center for a 15 hour burn till 6:00pm tomorrow. Not that I work that long lol, but I like to eat dinner before tending the furnace. Call me ANYTHING except late fer dinner :lol:

The shallower coal bed recovers faster too..
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut/Stove Size Mix

Re: Need internal length and width dimensions for your firebox

PostBy: Sunny Boy On: Fri Jan 03, 2014 9:56 pm

5x15x375 = 28,125 BTU. Should be 6 x 16, but after 110 years of clinker scale build up on the firebrick, . . . and there was no advertised BTU rating in 1903. . . . . that's all I got. :roll:

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Need internal length and width dimensions for your firebox

PostBy: ddahlgren On: Sat Jan 04, 2014 8:01 am

Would the grate design make a difference. I would think the size of the stove has to make a big difference too. There is a practical limit as to how hot you can run the stove. If you double the size of the firebox and do not double the surface area of the stove how can you double the btu rating? I think getting over 60,000 without a convection blower is going to be tough to do. Without a blower that would be 15 sq.ft. of heat exchanger running an average temperature of 800F.
ddahlgren
 
Hand Fed Coal Stove: Crane 404

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Re: Need internal length and width dimensions for your firebox

PostBy: Lightning On: Sat Jan 04, 2014 8:08 am

In my opinion it would be volume of coal at a specific reasonable depth that would ultimately dictate maximum Btu output.

BUT - there would also be a needed surface area for heat transfer depending on the medium. Whether that be transfer to water or directly to air.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut/Stove Size Mix

Re: Need internal length and width dimensions for your firebox

PostBy: lsayre On: Sat Jan 04, 2014 9:11 am

As i understand it, anthracite that is being properly supplied its combustion air from below will only burn in a band at a thickness of a couple to at most a few scant inches deep. Otherwise hopper stoves or AA/AHS boilers would be burning right up into their supply hopper and/or into their feed augers. If the height of the burning coal bed is a relative constant, then it will not change a mere cross sectional comparisons results.

Example for a firebox of 15" L X 15" width vs. a firebox of 10" L x 10" width:

15 x 15 = 225 square inches
10 x 10 = 100 square inches

225 / 100 = 2.25

Ratio = 2.25: 1

Now add a bed of coal burning at a height of 2.5" (or whatever) for both stoves and then compare their ratios again:

15 x 15 x 2.5 = 562.5 cubic inches
10 x 10 x 2.5 = 250 cubic inches

562.5 / 250 = 2.25

Ratio remains = 2.25:1

Therefore the height of the burning coal bed does not enter into the ratio equation, and it only makes this simple method way more complicated.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Need internal length and width dimensions for your firebox

PostBy: Sunny Boy On: Sat Jan 04, 2014 10:41 am

As we know, some coal beds burn deeper than others and those stoves can put out a lot of heat for their coal bed top surface area.

At only 5-6 inches deep, my range is burning all the way to the grates, unless I leave it filled with a lot of ash. Then it tends to slow down and the surface temps and heat output drop way off.

And how the dampers are set affects heat output for that amount of coal burning also. Well shaken and fully loaded with fresh coal, my range will burn through the night, for 10-11 hours, with burning coal from the grates on up. Damped down like that it just burns much more slowly, but the entire coal bed is burning. As a result, the heat output drops back some compared to when the primary damper and MPD are more opening during the day when we are cooking. If we really want it hot, opening the dampers more cranks out more heat, but still, the coal bed is burning side-to-side, end-to-end, and grates-to-top.

If you have a coal bed 10 or more inches deep, like some parlor stoves have, and after shaking the grates you see that glow in the ash pan, your burning coal to about the full depth of the coal bed. That's the surface area times the depth of burn equals total volume of coal producing heat. If it were only burning the top few inches, the heat volume (BTU's) would be less.

Therefore, I think the height of the bed that's burning should also be a factor in BTU rate.

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Need internal length and width dimensions for your firebox

PostBy: lsayre On: Sat Jan 04, 2014 11:02 am

Is the entire coal bed really burning simultaneously, or is it only the volatiles that are burning at the very top of the coal bed (regardless of the depth of the bed)? If so, when you shake down, wouldn't it be all ashes going out, and no unburned coal remaining after each shake down?

Why stop there? Why not burn right into the hopper?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Need internal length and width dimensions for your firebox

PostBy: ddahlgren On: Sat Jan 04, 2014 11:43 am

For the record my Crane 404 measures 18 long 7.25 wide 5 deep. Being 30+ years old it is not perfectly square.
I think at the end of the day the size of the heat exchanger limits total output and the size of the grate tells you if you could possibly fire the heat exchanger to a usable temperature.
ddahlgren
 
Hand Fed Coal Stove: Crane 404

Re: Need internal length and width dimensions for your firebox

PostBy: lsayre On: Sat Jan 04, 2014 11:49 am

ddahlgren wrote:For the record my Crane 404 measures 18 long 7.25 wide 5 deep. Being 30+ years old it is not perfectly square.
I think at the end of the day the size of the heat exchanger limits total output and the size of the grate tells you if you could possibly fire the heat exchanger to a usable temperature.


Thanks ddahlgren! Assuming these are internal firebrick to firebrick dimensions gives you:

18 x 7.5 x 375 = 50,625 max BTU's

Doug, how well does this compare with the nominal BTU rating for the Crane 404?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Need internal length and width dimensions for your firebox

PostBy: Lightning On: Sat Jan 04, 2014 11:59 am

Right now I have 10 inch deep coal bed. The entire depth is burning. Heat output is based on combustion air coming in (available oxygen). Coal won't burn up into a hopper unless it can follow an oxygen source.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut/Stove Size Mix

Re: Need internal length and width dimensions for your firebox

PostBy: lsayre On: Sat Jan 04, 2014 12:06 pm

So far the list reads as follows per the simple formula:

Hitzer 983 insert = 161,250 BTU's
DS Machine model 1627 = 162,000 BTU's
Glenwood 208 cook stove = 28,125 current BTU's (and was good for 36,000 BTU's before the firebricks got coated with age and use)
Crane 404 = 50,625 BTU's

Hope I haven't missed any.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Need internal length and width dimensions for your firebox

PostBy: Sunny Boy On: Sat Jan 04, 2014 12:11 pm

lsayre wrote:Is the entire coal bed really burning simultaneously, or is it only the volatiles that are burning at the very top of the coal bed (regardless of the depth of the bed)? If so, when you shake down, wouldn't it be all ashes going out, and no unburned coal remaining after each shake down?

Why stop there? Why not burn right into the hopper?



Larry,

Yes, the kitchen range's coal bed is all glowing coals right down to the grates. There is a thin layer of ash that I leave on the grates during the day, but that ash layer has many gaps that the primary air coming in keeps open. The ash drawer area under the grates is still lit up from burning coal until it's time to shake and top off with fresh coal.

Because the range firebox doesn't hold as much coal, depth-wise, it gets shaken and topped off several times during the day. Starting with, when I wake up in the morning, then about a 30-45 minutes before cooking meals to raise the top plate temps up to cooking temps from just heating temps (a difference of about 100 degrees).

If we're doing a long baking session, such as a large chicken, turkey, or ham, it gets a quick shake and light top-off about midway through the baking to keep oven temps up.

At bed time, it gets a very thorough shake down and filled full with successive layers until it's filled right up to the top with burning coal. Once all the coal is burning (still has lots of blue ladies, but with built-in secondary air leaks around the removable top plates there's never any danger of puff backs). Then the primary is closed to a sliver, the oven and water tank dampers are put in in-direct mode, the MPD closed fully, and it's damped down for the over-night.

No hoppers to worry about burning through on my kitchen range, or my Glenwood 118 Oak. ;)

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Need internal length and width dimensions for your firebox

PostBy: Lightning On: Sat Jan 04, 2014 12:17 pm

Mine is 28 x 17 on top and 28 x 12 at the bottom 9 inches deep with a trapezoidial shape. Not sure how to fit that into the equation lol.

Sorry it's sideways lol
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Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut/Stove Size Mix

Re: Need internal length and width dimensions for your firebox

PostBy: Sunny Boy On: Sat Jan 04, 2014 12:25 pm

FWIW, just to compare for grins.

Those 160K BTU ranges are about what a very large oil burner would do. My Oneida oil furnace is rated 250K BTU output with a nozzle rated at 3 gallons an hour and the fan speed up to max. I have a 1.5 gallon nozzle in it and the fan at half speed. That's enough to keep this 4000 square feet of drafty 17 room Victorian heated down into below zero range.

I have my own equipment to do my own tune-ups. It CO2 tests out at about 80% efficient. Because I have extra storage to get best cash price in bulk and have to keep track of when to order, I have about 15 years of measuring and tracking daily oil consumption too. For the coldest months, January and Feb, it averages 20 gallons a day. When it's below zero, it uses about 22-24 gallons a day.

So that should give some info for how well the big coal stoves compare.

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Need internal length and width dimensions for your firebox

PostBy: lsayre On: Sat Jan 04, 2014 1:04 pm

Lightning wrote:Mine is 28 x 17 on top and 28 x 12 at the bottom 9 inches deep with a trapezoidial shape. Not sure how to fit that into the equation lol.

Sorry it's sideways lol


Thanks Lightning! Split the difference and you get:

28 x 14.5 x 375 = 152,250 max BTU's

What did the manufacturer rate it for with anthracite?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Visit Hitzer Stoves