Answer
Mar 10, 2026 - 02:02 PM
To heat a 40,000-gallon pool, you'll typically need a pool heater with at least 400,000 BTU output for efficient heating. One 400,000 BTU heater is usually sufficient, but using two 200,000 BTU heaters can provide redundancy and flexibility. The exact size may vary based on your climate, desired temperature increase, and how quickly you want to heat the pool.
