# Need internal length and width dimensions for your firebox

### Need internal length and width dimensions for your firebox

I initially posted this simplistic maximum BTU's calculating formula within another thread, but in order to attempt a wild stab at unifying the BTU output ratings of the various hand fired stoves across the many brands as well as the many decades, please give a go at calculating your stoves maximum rated BTU's based upon this very simple formula, and report your results. Measurements should be taken from Inside of firebrick to inside of firebrick. Only concerned with length and width (or diameter if round). No concern for firebox depth. I don't want to complicate things much. When you report your calculated BTU's as derived from this formula, also give us the manufacturers listed BTU's for comparison if available.

If the firebox is square or rectangular: L x W x 375 = Maximum BTU's

If the firebox is round: Radius Squared x 3.1416 x 375 = Maximum BTU's

Disclaimer: Please do not attempt taking measurements while stove is hot!
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

So CRAP Larry, this is dead till spring?????????????? -----------------
freetown fred

Hand Fed Coal Stove: HITZER 50-93
Coal Size/Type: BLASCHAK Nut/Stove mix

### Re: Need internal length and width dimensions for your firebox

freetown fred wrote:So CRAP Larry, this is dead till spring?????????????? -----------------

No guesses allowed, so it very well could be!
Last edited by lsayre on Fri Jan 03, 2014 8:32 pm, edited 1 time in total.
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

Damn! I wish I'd read your disclaimer Larry. I got blisters on my fingers!!
coalkirk

Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

### Re: Need internal length and width dimensions for your firebox

coalkirk wrote:Damn! I wish I'd read your disclaimer Larry. I got blisters on my fingers!!

Ouch!
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

Larry,I have 20"w x 21.50"d and using your formula I came up with 161,250 and the manufacture says its 100,000 so I have to ask why do you need to know?

Keepaeyeonit.

PS. you owe me a new tape(12' Stanley)
Keepaeyeonit

Hand Fed Coal Stove: Hitzer 983 insert
Coal Size/Type: Mammoth nut
Other Heating: oil furnace,and a crappy heat pump

### Re: Need internal length and width dimensions for your firebox

Keepaeyeonit wrote:Larry,I have 20"w x 21.50"d and using your formula I came up with 161,250 and the manufacture says its 100,000 so I have to ask why do you need to know?

Keepaeyeonit.

PS. you owe me a new tape(12' Stanley)

Sorry about the tape! Did you read the disclaimer? Are those inside to inside of the firebrick measurements? The formula seems to work well for DS Machine stoves. Perhaps inserts work differently? You know me though. Always curious.
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

Keepaeyeonit wrote:Larry,I have 20"w x 21.50"d and using your formula I came up with 161,250 and the manufacture says its 100,000 so I have to ask why do you need to know?

Keepaeyeonit.

PS. you owe me a new tape(12' Stanley)
Larry knew someone would try to get a new tape out of him. That's what the disclaimer is for.......
oliver power

Stoker Coal Boiler: KEYSTOKER Kaa-2
Hand Fed Coal Stove: Hitzer 50-93 & 30-95, Vigilant (pre-Vigilant-II)
Baseburners & Antiques: MANY (Mostly when burning wood)
Stove/Furnace Make: HITZER / KEYSTOKER
Stove/Furnace Model: 50-93 & 30-95 , Kaa-2

### Re: Need internal length and width dimensions for your firebox

Uh, How would that work for a "V" shaped firebox??
Lightning

Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut/Stove Size Mix

### Re: Need internal length and width dimensions for your firebox

Lightning wrote:Uh, How would that work for a "V" shaped firebox??

I just knew there would be kinks in this. Keeping it simple isn't going to be as simple as I thought! Already burnt fingers and a toasted tape measure, and now this!

Where does the majority of the coal burn at? How about 2" down from the top of the 'V' sloped firebricks?
Last edited by lsayre on Fri Jan 03, 2014 8:50 pm, edited 1 time in total.
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

Yes sir, Inside of the brick(Hitzers dimensions are 20.50W x 21.25D)and I even have brick along the front that I added and I didn't see your disclaimer you have to remember I'm a coal burning Neanderthal .Keepaeyeonit
Keepaeyeonit

Hand Fed Coal Stove: Hitzer 983 insert
Coal Size/Type: Mammoth nut
Other Heating: oil furnace,and a crappy heat pump

### Re: Need internal length and width dimensions for your firebox

Keepaeyeonit wrote:Yes sir, Inside of the brick(Hitzers dimensions are 20.50W x 21.25D)and I even have brick along the front that I added and I didn't see your disclaimer you have to remember I'm a coal burning Neanderthal .Keepaeyeonit

Perhaps you have a very conservatively rated heat monster there!
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

DS Machine model 1627
Advertised BTU= 170,000
Firebox dimensions is a huge 16"x 27", hence model 1627
I don't know about it's efficiency but it dam sure is cranking out some great heat in tonight's below zero weather we're having, I actually had the house too hot last night at 75*
Last edited by Bruce M on Fri Jan 03, 2014 8:59 pm, edited 1 time in total.
Bruce M

Hand Fed Coal Stove: DS Machine 1627 basement stove

### Re: Need internal length and width dimensions for your firebox

The formula for a trapezoid (I'm assuming that's what a cross section of your fire box would be) is the average width multiplied by the height.

So if I understand your formula correctly it would be.

(Width of bricks at top + width of grate / 2), x length of firebox, x 375= maximum btu output
carlherrnstein

Hot Air Coal Stoker Stove: combustioneer model 77B
Coal Size/Type: pea stoker/Ohio bituminous

### Re: Need internal length and width dimensions for your firebox

Bruce M wrote:DS Machine model 1627
Advertised BTU= 170,000
Firebox dimensions is a huge 16"x 27", hence model 1627
I don't know about it's efficiency but it dam sure is cranking out some great heat in tonight's below zero weather we're having, I actually had the house too hot last night at 75*

Thanks Bruce! 16" x 27" x 375 = 162,000 max BTU's

As I said, the DS Machine stoves seem to work fairly well with this formula.
lsayre

Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)