So planning on getting a 400,000 BTU NG heater for a new build 15,000 - 15,500 gallon pool and was trying to do some cost estimates of running the heater. First my assumptions:

- from some research it appears that 1 BTU will heat 1 pound of water 1 degree.
- There are 8.34 pounds of water per gallon.
- 400,000 BTU heater puts out 400,000 BTUs per hour
- 1 CCF is roughly 102,500 BTU

So for this pool and heater I can expect to raise the pool 400,000 / (15,500 * 8.34 ) = 3.09 degrees per hour of run time.

My current cost for NG is $.19 per Ccf. so roughly 4 Ccf per hour to get 400,000 BTU or about 80 cents per hour of run time. Or if I want to think about it in cost per degree roughly 80 cents / 3.09 degrees = 25.85 cents per degree of temperature increase.

Is my math correct? It seems like it will just cost me 26 cents and 20 minutes to raise my pool 1 degree.