# Q&A BTU ratings of various fuels

Posted By QandA, Jun 17, 2007 at 7:32 PM

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### QandA New Member 2. ```NULL ``` Staff Member

Nov 27, 2012
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Question:

I am trying to determine if a given size coal stove will heat a given volume of air to over 120F. The application is an eight by eight foot Sauna. I need 30,000 btu. 9kw of Electric will do it but what size firebox do I need for wood or for coal? How much energy per lb. (or any other unit) in btus does coal contain, wood, propane, natural gas etc. contain? Where is to table that will tell me this?

Http://chi.hearth.com/addcalc.html compares the cost of various fuels.

9KW is approx 32,000 BTU per hour. Each pound of coal produces about 14,000 BTU input, or 10,000 output in a decent stove. So, burning three pounds per hour would do the job.

In the case of wood, about 5,000 BTU per pound per hour, so it would take 6 lbs/hour to match the electric heater.

Either should be easily attainable with even the smaller stoves. Wood may be preferable to coal since it heats up much faster.