The Hayward Universal HC Series HDF400 Dual Fuel Heater is designed for easy replacement of existing heaters in an existing pad. It features dual-fuel technology, allowing it to efficiently operate on either natural gas or propane. The heater is specifically engineered to fit seamlessly with Hayward plumbing adapters, making installation quick and hassle-free. Its drop-in capability ensures a straightforward and effortless replacement process. In addition to its dual-fuel capability and adaptable plumbing, the Hayward Universal HC Series HDF400 stands out with its zero wall-clearance design. This feature allows for flexible installation options, making it suitable for even the most space-constrained locations. Despite its compact size, the heater is incredibly powerful and durable. It is built to withstand demanding conditions and deliver reliable performance over an extended lifespan. Overall, the Hayward Universal HC Series HDF400 Dual Fuel Heater combines efficiency, adaptability, and size to provide an ideal heating solution for any pad.