Pentair MasterTemp 400 Natural Gas Heater vs Raypak 266,000 BTU Digital Gas Pool Heater

Buy the Pentair MasterTemp 400 for a large pool or spa that needs fast heat; its 400,000 BTU output and 82–84% efficiency move a big body of water quickly, and owners rate it 4.8/5. The Raypak 266 is the better fit for a smaller pool, roughly 25,000 gallons, where its lower output still heats well and its Protek Shield and two-year warranty address the corrosion that kills heaters. Both use copper heat exchangers and digital controls; the Pentair is the stronger heater, the Raypak the more protected one.

• Choose the Pentair MasterTemp 400 if you have a large pool or spa, need fast heat, and have the gas supply and electrical service to feed 400,000 BTU.
• Choose the Raypak 266 if your pool is around 25,000 gallons or less and you want corrosion protection and a two-year warranty over raw heating speed.