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Universal H-Series Heater 400,000 BTU - Propane Gas, Low NOx

Hayward

SKU: H400FDP

Hayward Universal H-Series gas heaters are the"universal" energy efficient remedy for any new or existing pool or spa.

Replacement SKU: HS400FDP

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.

  • EXPERT LINE products can only be purchased through your local pool professional or in-store.  Exclusions, other terms, and conditions may apply.
  • 3+ Year Parts and Labor Warranties*

*When sold by a Hayward Rewards® partner. Exclusions, other terms and conditions may apply.

Active Defrost No
Application New Construction, Renovation, Aftermarket
Boost Mode No
Brand Hayward
Channel Expert Line
Circuit Amps 5.5
Compressor Speed N/A
Cooling Capability No
Fuel Type Propane (LP)
GTIN 610377027267
Heating Capacity (BTU/hr) 400,000
Hertz - Heaters 60 Hz
Kilowatts 117 kW
Warranty - Labor 1-year
Low Ambient Operation Yes
Master Carton Qty 1
Maximum Breaker Size (Amps) 15
Minimum Operating Temperature 40 °F
Pallet Qty 1
Warranty - Parts 3-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 Yes
Series Heaters Universal H-Series Low NOx
Shipping Dimensions 30 " x 32.5 " x 39.5 "
Shipping Weight 213.5 lb
Side Clearance - Heaters 12"
Silent Mode No
Sub Brand N/A
Voltage - Heaters 120/240V
Water Flow Rate Max 125
Water Flow Rate Min 30

Questions & Answers

15 answered question(s)

06/24/26

Q: Why did the end of my heat exchanger tubes rot off y the o rings after two years use

A:
Hi, this is normally due to poor water chemistry.

By Hayward Support

06/24/26

Q: What is the warranty on the H-400 for propane and a dealer close to Fort Oglethorpe, Ga please

A:
Hi, when purchased from a local Hayward Authorized Dealer the H400FD heaters will have 3 years parts and 1 year labor warranty You can find a list of them by clicking on the Dealer Locator tab on the home page of our website Hayward.com

By Hayward Support

06/24/26

Q: Hi, I have a Hayward Pool heater and need to replace 3 gaskets. 2x3" round and 1 oval. The warranty says it's model W3H150FD/ W3H200FD/ W3H250FD/ WEH400FD. On the warranty it also has the Model number ( 5130004201C) but I need to know which of the above it is: 150/200/250/400. I have found someone who can get the parts( unless you can) but they said that you would be able to tell which from the Model number that I have given you. I have pictures but I'm not with the pool heater at this time. I hope you can help. Thanks, Susi

A:
Hi, the model number is on the heater. There is a label on one end that has the model number on it, and then if the front panel is taken off the model number is on the data plate in the bottom of the heater. You can find a list of local Hayward Authorized...

By Hayward Support

06/24/26

Q: I'm buying a new Hayward 400 heater since the prior one lasted 15 years. Question: Are the input / output ports the same distance from each other compared to the 2010 units? I'm hoping my plumbing pipes fit.

A:
Hi, your new heater should bolt right up! Nothing has changed on the plumbing configurations since 2010.

By Hayward Support

06/24/26

Q: What part # do I need For Model H400fdp Heat exchnger

A:
Hi, you need a FDXLHXA1400 heat exchanger.

By Hayward Support

06/24/26

Q: I’m looking to have this heater for my above ground pool. I see it’s recommended for in ground pools. Why will it not work for an above ground pool. We wanted a bigger heater then the one we had which was a 250k a friend has this heater for their above ground pool and loves it. Faster heating of water and better.

A:
Hi, the H250 is as you say designed for inground pools. Our above ground heater is the H135.

By Hayward Support

06/24/26

Q: What is the ventilation area needed for the 400,000 BTU gas heater?

A:
Hi, for indoor installations of gas appliances you would need to work with a local HVAC contractor to verify correct air and venting requirements.

By Hayward Support

06/24/26

Q: Looking for a propane heater for above ground pool. Will this one work?

A:
No. This heater is designed for inground pools, and is much too large for any above ground pool. We would recommend the H135IDP1 aboveground gas heater.

By Hayward Support

06/24/26

Q: Is the h400 item number 50033 the one with brass fittings?

A:
Hi, someone from our Technical Service Department will contact you via email.

By Hayward Support

06/24/26

Q: do you have a check list for maintenance

A:
Hi, the installation and service manual has recommended maintenance. It should ONLY be done by a qualified gas professional. Here's a link to the manual. https://hayward.com/media/akeneo_connector/asset_files/U/n/Universal_H_Series_Install_Manual_Bilingual_1f1f...

By Hayward Support

06/24/26

Q: What is the warranty on a Hayward natural gas heater

A:
Hi, it is 3 years parts and at least 1 year labor depending on where it is installed and by whom.

By Hayward Support

06/24/26

Q: How much propane does the SKU: H400FDP burn per hour?

A:
Hi, the H400 burns ~4.5 gallons of propane per hour of operation.

By Hayward Support

06/24/26

Q: Can the W3H400FDP heater run on 50Hz?

A:
it will not.

By Hayward Support

06/24/26

Q: What is the average pool size (gallons) recommended for this heater?

A:
Hi, there are several factors that play into how big a pool this 400,000 BTU heater can maintain. Ambient conditions, temperature desired, shade on the pool, speed to heat required, etc. Contact a local Hayward Authorized Dealer for help in choosing ...

By Hayward Support

06/24/26

Q: Any distributor in United Arab Emirates??

A:
Hi, someone from our International Group will be in touch via email.

By Hayward Support