Need Internal Length and Width Dimensions for Your Firebox

KingCoal wrote:just passing the 24 hr. mark at -35F . during that time I've had the DSM 1400 running at 525* and used 60#'s of nut to keep the house 66* i'm good with that.

we're going into the -40 / -50 range tonight and tomorrow, I expect it to be about the same.

Is that actual temp or wind chill temp?

SMITTY wrote:Been meaning to post this for a while now ...

Harman Mark lII:

20-5/8" x 13-7/8" x 9-1/4" in the back. In the front it's 4-7/8" deep ... but since you can heap the coal up in the middle, maybe that shorter measurement can be canceled out ...

20-5/8" x 13-7/8" x 375 = 107,314 max BTU's.

20-5/8" x 9-1/4" x 375 = 71,543 BTU's

The top figure seems right for a Mark III.

lsayre wrote:

KingCoal wrote:just passing the 24 hr. mark at -35F . during that time I've had the DSM 1400 running at 525* and used 60#'s of nut to keep the house 66* i'm good with that.

we're going into the -40 / -50 range tonight and tomorrow, I expect it to be about the same.

Is that actual temp or wind chill temp?

wind chill, if that's what it feels like, that's what it is to me. we also didn't go as deep as they expected so that's real good.

KingCoal wrote:Larry, at 14 x 16 the DSM 1400 is rated at 80,000. the formula shows 84,000.

Lightning, 75 #'s a day ?!?

i'm running 45#'s a day at a constant 500* stove top, house is balmy to say the least.

we are about to get up to 12" of snow followed by 3 days not above 0* F and wind chills to -20* and under. i'll let you know how the use changes.

How big and tight is your house. I only ask to get some sort of guideline as to how much I might burn in a 404 once I fix the
##$%@! hinge pins... My house 1300 sq ft and very loose 1874 construction with single glazed windows.

ddahlgren wrote:

KingCoal wrote:Larry, at 14 x 16 the DSM 1400 is rated at 80,000. the formula shows 84,000.

Lightning, 75 #'s a day ?!?

i'm running 45#'s a day at a constant 500* stove top, house is balmy to say the least.

we are about to get up to 12" of snow followed by 3 days not above 0* F and wind chills to -20* and under. i'll let you know how the use changes.

How big and tight is your house. I only ask to get some sort of guideline as to how much I might burn in a 404 once I fix the
##$%@! hinge pins... My house 1300 sq ft and very loose 1874 construction with single glazed windows.

the first and second floor are matched at 625 sf. each. for about 1250 I guess.

this house is OLD,made entirely of native chocolate walnut, walls, floors, rafters, the whole thing. I could get more for it by taking it apart board by board and selling it off than it will ever be worth otherwise.

only has insulation in 2 of the first floor walls, none upstairs and little in the attic. single pane period windows ( covered with plastic ), except for 2 new replacements I put in the bathroom when I did a remod. in there.

hard to tell what you might use, but I have to say you sure have a great stove to work with.

A correction.

With the warm weather I shut down the range and did some long over-due maintenance.

I chiseled away most of the clinker scale build up on the fire box walls, back to the one inch original thickness of the fire box linings. After years of build up it was only about 5-1/2 inch wide, but it turns out that it was originally 7 inches wide - not the 6 inch I thought. It's now back to the 7 inch by 15 inch full size.

So that's 39,375 BTUs.

I also caulked all the leaking seams under the top, in the water tank jacket and all the oven seams. And tightened the spring handle of the secondary damper which was leaking air in over the fire. The right end of the stove farthest from the fire box, the top plates are running about 100 degrees hotter. Overall, the heat output has substantially increased, for just the same primary damper opening as before.

And, the oven temp has gone from normally in the 200 degrees at this moderate primary damper setting to the low 400 degree range.

Paul

Harman SF260 boiler 16X22=352 x 375=132000BTU, mfg rated output 130,000btu

wilder11354 wrote:Harman SF260 boiler 16X22=352 x 375=132000BTU, mfg rated output 130,000btu

That's the best fit to the formula so far!

Adding in some data computed via this method (some from within a different thread asking much the same thing) to consolidate it all in one location:

Hitzer 983 insert = 161,250 BTU's
DS Machine model 1627 = 162,000 BTU's
Glenwood 208 cook stove = 39,375 BTU's (corrected to 7" x 15" firebox dimensions)
Crane 404 = 50,625 BTU's
Crawford #40 = 42,400 BTU's
Glenwood #6 = 75,400 BTU's
Glenwood #8 = 95,400 BTU's
Many old stoves with 111 in their name = 35,600 BTU's
Many old stoves with 114 in their name = 57,700 BTU's
Many old stoves with 116 in their name = 75,400 BTU's
Many old stoves with 118 in their name = 95,400 BTU's
Harman Mark III = 107,300 BTU's
DS Machine model DS-1400 = 84,000 BTU's
Harman SF260 = 132,000 BTU's
American Standard Severn = 141,750 BTU's
Clayton 1537G = 126,000 to 152,250 BTU's

Interesting post Larry if we knew the surface area of each stove we would then know the average temperature you would have to run the stove at to get those ratings and a feel for how hard you have to push to get the rated heat.

I can do the Crane 404 and will this weekend.

ddahlgren wrote:Interesting post Larry if we knew the surface area of each stove we would then know the average temperature you would have to run the stove at to get those ratings and a feel for how hard you have to push to get the rated heat.

I can do the Crane 404 and will this weekend.

My guess would be glowing red in spots and burning whopper loads of coal to reach those ratings.

For 95,000 BTU's/hr. of input, and assuming anthracite at a potential of 12.150 BTU's (as received, not lab dried), that would mean burning through 7.8 lbs./Hr., or 187 lbs per day if that temperature was to be sustained for one day.

And for 162,000 BTU's of input you are burning through 13.3 lbs. of anthracite per hour, or 320 lbs. per day.

imho, this single post should be enough to put the whole subject of manufacturers BTU ratings to bed completely.

good for you Larry

I would think if you burned 50 lbs a day the best you can hope for is 25312/hr. on a perfect day at 100% efficiency... Burning 200 or 300 lbs. a day would seem like a full time job in a small stove and not melt it while doing it.

I think francob had it right when he said that in Europe all of these stoves would only be permitted to list BTU inputs of roughly half of their USA ratings. You would still be pushing them very hard to achieve half the USA rated input, but I believe it to be far more safely achievable and sustainable.

Based on that, a better formula for BTU input would be:

If the firebox is square or rectangular: L x W x 187 = Maximum (safe) BTU's of input
If the firebox is round: Radius Squared x 3.1416 x 187= Maximum (safe) BTU's of input

Allowing for 75% efficiency, the formulas to compute maximum BTU's of output would then become:

If the firebox is square or rectangular: L x W x 140 = Maximum (safe) BTU's of output
If the firebox is round: Radius Squared x 3.1416 x 140 = Maximum (safe) BTU's of output

All of the stoves we have looked at so far would then more honestly have achievable hourly BTU rated output potentials closer to those shown here:

Hitzer 983 insert = 60,500 BTU's
DS Machine model 1627 = 60,750 BTU's
Glenwood 208 cook stove = 14,775 BTU's
Crane 404 = 19,000 BTU's
Crawford #40 = 15,900 BTU's
Glenwood #6 = 28,300 BTU's
Glenwood #8 = 35,800 BTU's
Many old stoves with 111 in their name = 13,400 BTU's
Many old stoves with 114 in their name = 21,650 BTU's
Many old stoves with 116 in their name = 28,300 BTU's
Many old stoves with 118 in their name = 35,800 BTU's
Harman Mark III = 40,250 BTU's
DS Machine model DS-1400 = 31,500 BTU's
Harman SF260 = 49,500 BTU's
American Standard Severn = 53,200 BTU's
Clayton 1537G = 47,250 to 57,000 BTU's

Looking at the DS-1400, it would need to burn through 83 lbs of coal in a day to achieve this output. Does that sound doable on a really cold day?
And the Harman Mark III would need to burn through 106 lbs. of coal per day to achieve this output. Does this sound about right for a really cold day?

Larry,

concerning the calculated 83 #'s per day for the DSM 1400, even with my less than optimally sealed house, I can't imagine the weather needed to require that.

we had over 72 hrs. of -25 / -35 F wind chills here already and I burned 60 #'s per 24 hrs. ( putting 20 #'s in the stove every 8 hrs. ) at 525* stove temp. for that period. this was achieved with the intake flap 3/16" open and -.04 WC both MPD's closed to hold it there against the wind.

BUT, I have a small area being heated ( 1250 sf.) and I bought this size stove purposely, expecting NOT to need more than 1/2 it's rating even in the worst case situation, but having excellent reserve capacity if needed.

EDIT. you may have gone alittle far on the equation. i'd go half way back to "187", that would be 57,750 for the DSM 1400 and very realistic I think.

57,750 / 12,500 = 4.62 #'s per hour. I was burning 2.5 's per hr. at 525* during the coldest so I guess I could see putting 2 more pounds an hr. thru it, just not in MY house.