How much heat?

To heat a pool that has a volume of 13,500 gallons, I'm hearing 100,000 and 150,000 btus. Our neighbor has a 17,000 gal. pool, and was sold a 100k heater, which he ditched after a year for a heat pump (due to propane prices). Will a 150k heater be more costly to keep the pool warm than a lower btu unit? Is it overkill or is it a wash?

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Originally Posted by lauriefree

To heat a pool that has a volume of 13,500 gallons, I'm hearing 100,000 and 150,000 btus. Our neighbor has a 17,000 gal. pool, and was sold a 100k heater, which he ditched after a year for a heat pump (due to propane prices). Will a 150k heater be more costly to keep the pool warm than a lower btu unit? Is it overkill or is it a wash?

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It takes 8 BTU to heat a gallon 1 degree, so for a 13,500 gallon pool, it would take 108,000 BTU to raise it one degree. Size comes into play with speed. A 100,000 BTU/hr heater would raise your pool roughly 1 degree per hour. A 150,000BTU/hr unit would be roughly 50% faster.