# Coal Consumption: Theoretical Formula Vs. Practice

### Coal Consumption: Theoretical Formula Vs. Practice

The quasi-empirical formula that I use to calculate theoretical daily coal consumption is as follows:

Daily Coal Consumption = (Daily HDD's x 1.34) +4.33
where I assume 4.33 lbs. per day to be used for the homes DHW needs, and not for home heating
and where: daily HDD's = 65 - (days high temp + days low temp)/2
and where I burn a flat 14.75 lbs. on all warm days with daily HDD's that are at or below 7.78
[the above 14.75 lbs. figure is because (7.78 x 1.34) + 4.33 = 14.75 lbs., and because my boiler needs to burn at least 14.75 lbs. per day to maintain its fire]

Here is my theoretical vs. actual coal consumption this season by month using the above empirical formula:

October: Theoretical = 775 lbs., Actual = 756 lbs.
November: Theoretical = 1,222 lbs., Actual = 1,110 lbs.
December: Theoretical = 1,351 lbs., Actual = 1,303 lbs.
January: Theoretical = 1,694 lbs., Actual = 1,705 lbs.
February: Theoretical = 1,598 lbs., Actual = 1,595 lbs.
March: Theoretical = 1,443 lbs., Actual = 1,466 lbs.
April (so far): Theoretical = 290 lbs, Actual = 270 lbs.

Totals to date: Theoretical = 8,373 lbs., Actual = 8,205 lbs.
lsayre

Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)

### Re: Coal Consumption: Theoretical Formula Vs. Practice

Pretty close calculating. I played with numbers and
spread sheets for a year or so after I built my boiler.
Now I just empty the ash pan and fill the hopper.
When the bin gets low I call for more coal.

If you want to really get crazy, try a different coal next year
as see if the formula holds out.
tsb

Stoker Coal Boiler: Binford 2000
Hot Air Coal Stoker Stove: LL Pioneer top vent
Hand Fed Coal Stove: Saey Hanover II
Baseburners & Antiques: Grander Golden Oak , Glenwood # 6
Coal Size/Type: All of them

### Re: Coal Consumption: Theoretical Formula Vs. Practice

I already had to modify it for Harmony, as I burned noticeably more Blaschak per HDD last heating season. Something like 7% more.
lsayre

Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)

### Re: Coal Consumption: Theoretical Formula Vs. Practice

So in theory, if you insulate, you should be able to drop the 1.34 to a lower number.
mozz

Stoker Coal Boiler: Axeman Anderson 1982 AA-130 Steam

### Re: Coal Consumption: Theoretical Formula Vs. Practice

mozz wrote:So in theory, if you insulate, you should be able to drop the 1.34 to a lower number.

Correct!
lsayre

Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)