The Hayward H400FDNASME Universal H-Series ASME Pool & Spa Heater is a high capacity, low-NOx natural gas heater engineered for commercial grade reliability and fast heat up performance. Rated at 400,000 BTU, this ASME certified heater is designed for large residential pools, commercial pools, and installations requiring code-compliant pressure vessel construction. Built with a premium cupro nickel heat exchanger, bronze header, and ASME pressure relief valve as standard equipment, the H400FDNASME delivers durable, efficient heating while meeting strict emissions and safety requirements.

Key Features

• 400,000 BTU natural gas heater provides rapid heat up for large residential and commercial pool and spa applications
• ASME certified pressure vessel meets commercial code requirements in many states and municipalities
• Low NOx forced draft combustion system complies with stringent air quality regulations
• Patented cupro nickel heat exchanger offers superior resistance to corrosion and aggressive water chemistry
• Low lead bronze header with patented bypass design improves hydraulic efficiency and extends heater life
• ASME pressure relief valve included as standard for enhanced system safety
• Universal left or right side plumbing, gas, and electrical connections simplify installation and retrofits
• Front single panel access allows fast service and maintenance without rear clearance
• Certified for installation on combustible surfaces with non corrosive feet
• Designed for indoor or outdoor installation with appropriate venting

Product Overview

The Hayward H400FDNASME Universal H-Series Heater is built to deliver powerful, reliable heating performance while meeting the structural and safety standards required for ASME regulated installations. Its 400,000 BTU output ensures fast temperature recovery, making it ideal for larger pools, high use facilities, and environments where downtime must be minimized.

Engineered with Hayward’s industry leading hydraulics, the H-Series ASME heater includes premium components as standard equipment, eliminating the need for costly upgrades. The cupro nickel heat exchanger and bronze header provide exceptional durability in demanding water conditions, while the low-NOx combustion system supports environmental compliance. With flexible installation options and service friendly access, the H400FDNASME is a dependable, professional grade solution for long term pool and spa heating performance.