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HAYWARD UNIVERSAL H-SERIES W3H400FDN LOW NOX NATURAL GAS POOL & SPA HEATER – 400K BTU, CUPRO-NICKEL HEAT EXCHANGER
Dimensions: 24" H x 34" W x 29.5" D
Heating Capacity: 399,900 BTU
Thermal Efficiency: 84%
Fuel Type: Natural Gas
Heat Exchanger: Cupro-Nickel
Water Flow Rate: 30-125 GPM
Emissions: Low NOx
Installation: Indoor & Outdoor
The Hayward W3H400FDN Universal H-Series Low NOx Natural Gas Pool & Spa Heater delivers 399,900 BTU of heating performance for in-ground residential pools and spas. It is part of Hayward's Universal H-Series line, designed as a direct fit for new construction, renovation, and aftermarket replacement installations.
The cupro-nickel heat exchanger provides excellent resistance to salt water and pool chemical corrosion, while the patented bypass header design manages water flow through the exchanger to protect it from thermal stress.
A forced-draft combustion system moves air through the combustion chamber at a precise flow rate, which eliminates the need for a high-wind stack and allows the heater to operate reliably in exposed outdoor locations. The unit accepts a water flow rate of 30-125 GPM and ships with CPVC union plumbing connections for straightforward installation.
Key Features
- 399,900 BTU heating capacity
- 84% thermal efficiency
- Natural Gas
- 30-125 GPM water flow rate
- Cupro-nickel heat exchanger for salt water and chemical corrosion resistance
- Patented bypass header design
- Forced-draft combustion system - no high-wind stack required
- Low NOx design meeting SCAQMD Rule 1146.2
- Included 2" x 2-1/2" CPVC union plumbing connections
- Low ambient operation down to 40 F
- Compact cabinet with 12" side and 6" rear clearance requirements
- Indoor and outdoor installation capability
- 3-year parts warranty
Specifications
| Specification | Details |
| Brand | Hayward |
| Part Number | W3H400FDN |
| Model | H400FDN |
| Series | Universal H-Series |
| Fuel Type | Natural Gas |
| BTU Input | 399,900 BTU |
| Thermal Efficiency | 84% |
| Heat Exchanger | Cupro-Nickel |
| Water Flow Rate | 30-125 GPM |
| Plumbing Connections | 2" x 2-1/2" CPVC Union |
| Dimensions | 24" H x 34" W x 29.5" D |
| Unit Weight | 195 lbs |
| Shipping Weight | 213.5 lbs |
| Voltage | 120/240V |
| Phase | Single Phase |
| Frequency | 60 Hz |
| Circuit Amps | 5.5 A |
| Maximum Breaker Size | 15 A |
| Emissions | Low NOx (Meets SCAQMD Rule 1146.2) |
| Clearances | 12" Sides / 6" Rear |
| Minimum Operating Temperature | 40 F |
| Pool Type | In-Ground |
| Installation | Indoor & Outdoor |
| Warranty | 3-Year Parts / 1-Year Labor |
What's Included
- Hayward W3H400FDN Universal H-Series Low NOx Natural Gas Pool & Spa Heater
- Cupro-nickel heat exchanger assembly
- Two 2" x 2-1/2" CPVC union plumbing connections
- Installation and operation documentation
The Hayward W3H400FDN pairs 399,900 BTU of heating output with a corrosion-resistant cupro-nickel heat exchanger and a forced-draft burner, making it a dependable choice for in-ground residential pools and spas.
Learn more at Hayward:
https://www.hayward.com/universal-h-series-heater-400-000-btu-natural-gas-low-nox-h400fdn.html
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