Universal H-Series pool and spa heaters from Hayward® boast industry leading hydraulic performance coupled with lightning-fast speed-to heat capability. Rated at 83% thermal efficiency, this powerful heater offers you less time to wait and more time enjoying the water. Extends the swim season, delivering 83% thermal efficiency powered by natural gas Designed for on-demand heat performance with fast heat up times Corrosion-resistant titanium heat exchanger works well with salt systems Compare Savings Designed with "totally managed" water flow, Universal H-Series heaters save energy (and money) by reducing pump run time. Universal H-Series heaters boast industry-leading hydraulic performance coupled with lightning-fast speed-to-heat capability. Compare savings with the Hayward Energy Calculator