Hayward W3H400FDN Universal H-Series Natural Gas 400,000 BTU Low NOx

Hayward W3H400FDN Universal H-Series Natural Gas Pool Heater – 400,000 BTU Low NOx

The Hayward Universal H-Series W3H400FDN is the highest-capacity heater in the H-Series lineup, delivering 400,000 BTU of heating power for large residential pools and high-demand spa systems. Designed for rapid heat-up performance, this natural gas heater allows pool owners to reach desired temperatures quickly while maintaining efficient operation.

The heater features a corrosion-resistant Cupro-Nickel heat exchanger and advanced hydraulic design that improves durability and protects against erosion from high water flow rates. Its Low NOx emissions design meets strict environmental standards while maintaining strong heating performance. :contentReference[oaicite:2]{index=2}

Maximum Heating Power for Large Pools

The Universal H-Series heater combines fan-assisted combustion with a digital LED control panel for accurate temperature control and system diagnostics. Flexible plumbing and gas connections allow easy installation on both new and existing equipment pads.

Key Features

• 400,000 BTU natural gas heating capacity
• Universal H-Series Low NOx emissions heater
• Cupro-Nickel heat exchanger for superior corrosion resistance
• Fan-assisted combustion system for consistent heating
• Electronic ignition with LED diagnostic controls
• Polymer header protects against high-flow erosion
• 2 in x 2.5 in CPVC union plumbing connections
• Designed for large residential in-ground pools and spas