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Universal H-Series Heater 400,000 BTU - Propane Gas, Low NOx (Open Line)

Hayward

SKU: W3H400FDP

The Universal H-Series is an energy efficient, high performance, installation adaptable commitment to the pool service professional.

Replacement SKU: W3HS400FDP

Features

Hayward Universal H-Series gas heaters are the “universal” energy efficient remedy for any new or existing pool or spa. An industry-leading hydraulic design reduces circulation pump run time to provide energy savings of up to 18% when compared to less efficient competitors. The energy efficiency of the Universal H-Series gas heater combines with environmentally friendly low NOx emissions, a standard cupro nickel heat exchanger, and ultimate installation flexibility to responsibly heat a pool or spa today and for years to come.

Features and Benefits

  • Standard cupro nickel heat exchanger
  • Excellent salt water and chemical corrosion resistance
  • Exclusive "Totally Managed" cupro nickel heat exchanger water flow
  • Same water velocity through all tubes for faster heating
  • Patented header by-pass design
  • Reduction in pump run-time results in significant cost savings
  • 2" x 2 1/2" CPVC union plumbing connections
  • Forced draft system constantly moves air through the combustion chamber at a precise flow rate, eliminating the need for a high-wind stack
  • Low NOx emissions - meets clean air quality standards

NOTE: Hayward Universal H-Series heaters meet or exceed the South Coast Air Quality Management District (SCAQMD Rule 1146.2) Low NOx emissions standards in all Low NOx areas that apply the SCAQMD standard.

Active Defrost No
Application New Construction, Renovation, Aftermarket
Boost Mode No
Brand Hayward
Channel Open Line
Circuit Amps 5.5
Compressor Speed N/A
Cooling Capability No
Fuel Type Propane (LP)
GTIN 610377387279
Heating Capacity (BTU/hr) 400,000
Hertz - Heaters 60 Hz
Kilowatts 117 kW
Warranty - Labor None
Low Ambient Operation Yes
Master Carton Qty 1
Maximum Breaker Size (Amps) 15
Minimum Operating Temperature 40 °F
Pallet Qty 1
Warranty - Parts 1-year
Phase - Heaters 1
Pool Type In Ground
Product Dimensions 24 " x 34 " x 29.5 "
Product Height 24 in
Product Length 29.5 in
Product Weight 195 lb
Product Width 34 in
Rear Clearance - Heaters 6"
Refrigerant No
Series Heaters Universal H-Series
Shipping Dimensions 30.6 " x 32.8 " x 39.6 "
Shipping Weight 214 lb
Side Clearance - Heaters 12"
Silent Mode No
Voltage - Heaters 120/240V
Water Flow Rate Max 125
Water Flow Rate Min 30

Questions & Answers

5 answered question(s)

06/24/26

Q: What indoor vent kit do I need for this specific heater? W3H400FDP

A:
Hi, that would depend on the type of venting your installer is planning to use. For negative pressure venting you will need a UHXNEGVT14008. For positive pressure venting you will need a UHXPOSHZ14006 vent kit, and also either a UHXDVA006 for use with...

By Hayward Support

06/24/26

Q: Can this be easily converted to natural gas?

A:
Hi, this heater can be converted, but it would need to be done by a certified gas service technician. You can find a list of them on our website by clicking on the Dealer Locator tab on the home page of our website Hayward.com

By Hayward Support

06/24/26

Q: What is the recommended propane water column for peak performance, best burner function?

A:
Hi, the H400FDP propane heater requires 10-13" wc inlet gas pressure, and 6.8-7.0" wc manifold pressure.

By Hayward Support

06/24/26

Q: What's the price of this W3H400FDP

A:
Hi, we do not sell direct and therefore do not quote pricing. You can find a list of Hayward Authorized Dealers by clicking on the dealer locator tab in the upper right on the home page of our website Hayward.com

By Hayward Support

06/24/26

Q: What gas pressure does the heater work off of

A:
Hello Brian, This is an email regarding Case # 00465377. Thank you for contacting Hayward Support for assistance. Our apologies for the delay in responding to your enquiry. Attached to this email is a PDF of the product manual for the Universal H-...

By Hayward Support