Hayward HDF275 Universal HC Series NP/LG Dual-Fuel Low NOx Heater 275K BTU - Universal HC Series dual-fuel technology gas heaters are uniquely engineered for use with Hayward® plumbing adapters, making them an easy drop-in replacement for other heater brands. The heat exchanger is made from cupro nickel for added reliability, and the easy-out air/gas mixing orifice makes propane conversion fast and simple. The industry's smallest footprint* with zero wall clearance fits in even the most compact equipment pads, while the refined gas controls and remote connectivity provide a simple user experience with added service convenience