How fast can pool heater heat my pool?

How do you figure out the size of pool heater that you need to heat a 16x30 13000 gallon in-ground gunite pool?

• Answer:

  Heat your pool right While the heater manufacturers have all kinds of charts and graphs, as a pool service provider in the desert southwest U.S., I can tell you that you want at LEAST 300,000 BTU's, depending on your local climate. In colder areas where you need to heat the water from a lower starting temperature, I would recommend 400,000 BTU's (about as big as they get for residential pools). The initial expense is slightly higher for the larger units, however, they tend to heat the water with more fuel efficiency as they make the water hotter, faster, thereby requiring the unit to burn fuel for less time.