# How many BTUs does it take to heat a 1250 gallon pool of water from 50 degrees to 82 degrees?

{Sigh} I hate English units.

A BTU is defined as the amount of heat required to raise the temperature of 1 lb of water by 1 deg F.

The basic relation is

Q = mcdT

Heat = mass * heat capacity * change in temperature.

A gallon of water weighs about 8 lb, so you're talking about 500,000 gal * 8 lb/gal = 4 million pounds.

The constant c for water, by the definition given above is 1 Btu/lb-deg F.

So

Q = 4 million pounds * 1 Btu/lb-degF * 32 deg F = 128 million BTU

Note: 500,000 gal should be changed to 1250 gal or 3.2 million BTU?

### How many BTUs will it take to change 1 gallon of water at 32 degrees to ice at 32 degrees?

You would need to remove approximately 1200 BTUs of heat to convert a gallon of water to ice. There are 8.34 lb in a gallon of water, which converting to lb-moles is 0.463. The latent heat of crystallization for water is -2583.4 BTU/lb-mole. Multiplying the two together and you get -1197 BTUs, which means you need to remove that amount of heat to convert the gallon of water to ice.

### How many BTU's does it take to evaporate one pound of water?

BTUs to Evaporate One Pound of Water Quick Answer: Somewhere around 1000BTU/lb Long answer: It depends on the temperature of the water you start with. Before you can evaporate the water, you must heat it to it's boiling point. The warmer the water you start with the fewer BTUs will be needed to heat the water to its boiling point. Keep in mind the BTUs require to raise the water to its boiling point are…