BEST FOR: In-ground pools and spas with a surface area up to 400 ft. where natural gas is available. Its low environmental impact makes it ideal for pools and spas located where low-NOx emissions are required.PREMIUM PERFORMANCE: The Hayward Universal H-Series 150,000 BTU Natural Gas Heater delivers fast premium heating performance for years of reliable, long-lasting comfort.CORROSION PROTECTION: The Universal H-Series boasts exceptional protection against corrosion and premature failure caused by unbalanced water chemistry.ENERGY SAVINGS: The efficient, industry-leading design reduces circulation pump run time to provide energy savings.EASY-TO-USE: Intuitive front control panel provides easy operation, service and maintenance.