When it comes to cost, the conversation starts with equipment price. Gas heaters generally enter the market at a lower price point. A compact 175,000–200,000 BTU model often sells for around $1,800 to $2,500. Mid-range heaters in the 250,000–300,000 BTU class usually run between $2,500 and $3,500, while the biggest 350,000–400,000 BTU units for large pools can exceed $5,000. Heat pumps begin higher. Most standard residential models range from $2,800 to $4,000, and larger 120,000–140,000 BTU or inverter-driven units with heat-and-chill features can climb to $6,000 or even $7,500.

The real difference shows up in monthly energy bills. A gas heater running on natural gas typically costs $200 to $400 a month to operate, depending on pool size and how frequently it’s used. Propane can push those costs even higher. Electricity costs for a heat pump are much lower, usually falling between $50 and $150 per month in most regions. That efficiency makes heat pumps especially attractive for homeowners in warmer climates where the units can draw plenty of heat from the surrounding air.

Over the lifetime of the equipment, gas heaters tend to last five to ten years, which means most owners will spend between $12,000 and $18,000 over a decade when fuel and equipment are combined. Heat pumps last longer—typically ten to fifteen years—and although they cost more to install, the lower operating expense brings total ten-year ownership costs closer to $7,000 to $10,000.