The Hayward Universal H-Series gas heater is the "universal" energy efficient remedy for any new or existing pool or spa. An industry-leading hydraulic design reduces circulation pump run time to provide energy savings of up to 18% when compared to less efficient competitors. The energy efficiency of the Universal H-Series gas heater combines with environmentally friendly low NOx emissions, a standard cupro nickel heat exchanger, and ultimate installation flexibility to responsibly heat a pool or spa today and for years to come.