Pentair Master-Temp In-Ground High-Performance Low-NOx Pool Heater Natural Gas 250,000 BTU Heavy Duty Cupro-Nickel P/N: 460806 Gas Type: Natural gas BTU Input: 300,000 Heater Size: 32.61" W x 23.02" D x 28.15" H Vent Diameter: Works for vent sizes 6-10" (Outdoor: Stackless Outdoor Venting System) Ignition: Hot Surface Ignition Thermostats: 2 (1 for Pool / 1 for Spa) 6" clearance on all sides needed for proper operation. New MasterTemp heaters offer all the efficiency, convenience and reliability features you want in a pool heater, plus a lot more. As easy to use as your home heating system, plus, use-friendly indicator lights make system operation and monitoring a snap. The compact design and super-quiet operation won't intrude on your poolside leisure time. Heavy-duty unit with cupro-nickel exchanger stands up to the harshest of applications, like low pH, high flow or heavy use.