How many gallons of water are needed to heat a 504 cubic feet greenhouse?
steve l asked:
I need to know how much water will be needed to keep the temperature above freezing in a greenhouse that is 12x7x7 if temperatures drop as low as 5F. I know metal cans filled with water, painted black absorb a lot of heat, but is 50 gallons enough?
I need to know how much water will be needed to keep the temperature above freezing in a greenhouse that is 12x7x7 if temperatures drop as low as 5F. I know metal cans filled with water, painted black absorb a lot of heat, but is 50 gallons enough?
I too am looking forward to hearing the answer….
Is 50 gallons enough?
Short answer: No way.
Long answer: A lot more data would be necessary to calculate the actual amount, including type of insulation, time to keep it warm, what temperature you want to maintain it at. One problem would be that the greenhouse would be overheated before until it cooled to suitable temperatures if you were to use enough water for the job.
A BTU, short for British Thermal Unit, is a basic measure of thermal (heat) energy. One BTU is the amount of energy needed to heat one pound of water one degree Fahrenheit. 50 gallons is 400 lbs of water, so if boiling water were allowed to cool to freezing, it would yield 2520 total bTUs. (400 lbs * 180 = 2520 TOTAL BTUs)
To give you an idea, most window single room air conditioners are 5000-10000 BTUs PER HOUR) and you’re not even talking about how much heat would be lost, and you’re talking about creating a kind of thermal inertia, not radiant or circulated heat.
To recap: No way.