Whats the Difference Between a Wood & Coal Stove?

Modern and vintage hand fired coal stove are similar to a wood stove and in some cases can burn either. They need to be regulated and fed by hand usually every 12 to 24 hours depending on your usage. They require no power to operate making them ideal for rural settings with long power outages.
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lsayre
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Posts: 12252
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Sep. 23, 2012 12:50 pm

65 degrees F. minus the days average temperature (in degrees F.) = Heating Degree Days (HDD)

The easiest way to calculate it (not exact) is:

65 - [(Days High Temp + Days Low Temp)/2] = HDD

Example:

Days high temp = 20 degrees F.
Days low temp = 5 degrees F.

65 - [(20 + 5)/2] = 52.5 HDD's

I find that the calculation as done above is improved overall by multiplying by a kludge (or fudge) factor of roughly 1.06, and I believe this is so because in the depths of the winter there are fewer daylight hours than dark hours in a day, and you are trying to estimate the days average temperature from only two data points (days high and days low).

Therefore, an improvement to the above formula (with admittedly an empirical kludge, also not exact) is:

(65 - [(Days High Temp + Days Low Temp)/2]) x 1.06 = HDD

The kludge bumps up the heating degree days for the example day above to 52.5 x 1.06 = 55.7 HDD's

In my case I would expect to burn 1.57lbs/HDD x 55.7 HDD's = 87.5 lbs. of coal for the example day.

Or you can just go here: http://www.degreedays.net/

***The company I work for uses HDD's to estimate its monthly heat bill, and to keep the energy company honest.***
*** Your energy company uses monthly HDD's to compute your bill when they send you an estimated rather than an actual monthly bill. ***
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

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Lightning
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Posts: 8303
Joined: Wed. Nov. 16, 2011 9:51 am
Hand Fed Coal Furnace: Overmodified/Bored out Clayton 1537
Coal Size/Type: Anthracite/Awesome Size
Location: Olean, NY

Post Sun. Sep. 23, 2012 1:56 pm

Oh wow, thank you for the detailed explanation :) I think this winter I will use that formula to calculate coal usage.. I agree with the "Kludge" factor since HI and Low temps don't represent a true average for the day lol... Thats very interesting!

Um but the 65 degree base.... Shouldn't that be the temp you keep your house at? I run my house 75 degrees 8-)

Visit Hitzer Stoves

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lsayre
Member
Posts: 12252
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Sep. 23, 2012 3:37 pm

Official HDD's are based at 65 degrees, but you are free to base as you see fit. Perhaps you will get even higher correlation of coal to HDD's in so doing?

The average temperature for the day is an integration function. The more data points, the better you can simulate this integration. 24 hourly temperature points summed and then divided by 24 would get you rather close overall. I choose to make it as simple as I can, and I reduce it to but two data points (using data that is readily available), accepting the error that this inevitably brings to the calculated HDD.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

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