Hayward H-Series Heaters - Further Reading

Hayward H-Series Heaters

Hayward has been producing different models of gas heaters under the H-Series label. It can be confusing when you have a problem and find information talking about a Hayward heater but not your specific model.

Universal H-Series

The Universal H-Series consist of the HXXXFDN, HXXXFDP, W3HXXXFDN, and W3XXXFDP models. N denotes Natural Gas, and P denotes propane gas. FD means the heater is Forced Draft using a blower to create air flow.

The H models are Hayward's EXPERT LINE products that are only available through your local pool professional. The W3H models are available through other channels. I believe they are functionally identical and the only difference will be Hayward's warranty.

Cupro nickel is the standard heat exchanger on the Universal H-Series gas heaters. Cupro nickel heat exchangers last longer than standard copper and superior corrosion resistance protects the heat exchanger from damage and premature failure caused by unbalanced water chemistry.


Altitude of Installation - Heaters may be installed at any altitude up to 10,100 ft above sea level, provided the appropriate modification(s) are performed. The altitudes which require modification vary depending on the model. Parts necessary to convert the heater for outdoor installation at altitudes up to 7,700 ft (minimum) are included with the heater. More information can be found on page 9 and 10 of the Installation Manual.

Universal H-Series Diagnostics Guide provides detailed diagnostics for troubleshooting problems and error codes.

IF Fault

IF, ignition failure, usually means it attempted to light and the flame went out. It will try three times and then give you the IF code. Could be as simple as a bad flame sensor. On the FD units, the flame sensor is a separate sensor and sometimes you can use emery cloth or steel wool to clean it and it will work.[1]


The HXXIDL heaters are from early 2000 vintage and were replaced by the Universal H-Series heaters. XXX is the BTU rating of the heater in thousands and IDL means "Induced Draft Low NOx". The Installation, Operation, & Service Procedures for the H250IDL2, H350IDL2 & H400IDL2 can be found here. Troubleshooting begins on page 36.

The IDL models use an air blower for the induced draft. There are apparently 4 different blower parts/kits available for the H400IDL2 heater:[2]

  • IDXLBWR1930 - Original model w/240V motor which is listed in the manual
  • IDXL2BWR1930 - New model w/120V Jakel motor, used in heaters mfg after 9/20/04, (I'm guessing this is the one I have mine is a Jakel motor which says 115V)
  • IDXL2BWR1931 - upgrade kit with yet another new blower w/120V Fasco motor, along with a new control board & vacuum switch - which I'm guessing are needed to make the switch from the Jakel to Fasco motor.
  • IDXL2BWR1932 - Newest blower w/120V Fasco motor, does not include new control board & vacuum switch - you would only buy this if your heater already has the 120V Fasco motor in it.

The original blower used in these heaters - model IDXLBWR1930 - was a 240V motor. Then in 9/2004 they updated it with a 120V Jakel motor. And then sometime after that (after S/N (21)130701100532001, according to several websites) they switched again to a 120V Fasco motor. The 120V Fasco motor is different from the older 120V Jakel model. The 120V Jakel motor pulls 1.3A and has a 9.0 MFD capacitor, and the newer Fasco motor uses 1.6A and has a 7.5 MFD capacitor.[3]

The heater is equipped with a Hot Surface Ignition Control System that automatically lights the burners. An external power supply is required to power the control system.

Sea Level/high altitude installation - The H-Series IDL heaters may be installed up to 2,000 feet of elevation above sea level.

HXXX Models


The HXXX comes in a millivolt model and an electronic ignition model.

The millivolt heater must be lit manually. The millivolt operated heater is equipped with a standing pilot and a thermopile (pilot generator). All of the electric current required to operate the controls within the heater is provided by the pilot generator. No external wiring or electrical connections are required.

The electronic ignition models are lit automatically on each call for heat. The electronic ignition system is equipped with the same basic controls as the millivolt operated heater but a direct spark ignition device (DS) is used to automatically light the main burners on each call for heat. With the DS module these controls operate on 24 volts so an external power source is required.

The HXXX models use a natural draft and do not have an air blower.

Sea level/high altitude installation - The early H-Series heaters may be installed up to 2000 feet of elevation above sea level. For elevations from 2000 to 4500 feet above sea level, heater shall be a high altitude model which has a suffix “H” in the heater model designation (Example: Model H400H1). For elevations above 4500 feet, consult Hayward Customer Service.

By now any of these HXXX series heaters are old and are rarely worth repairing. Even in their day they had consistent problems and poor performance. If you have one of these heaters and it is working then continue to run it often. Spiders love to lay eggs in the heater orifices and running it cooks them out and extends the life of the heater.

Lighting Pilot in Millivolt Heater

Normal sequence for lighting the millivolt (MV) pilot would be to turn the gas valve knob to the "pilot" position and push it down to allow gas flow to the pilot. While holding the gas valve knob down, push the piezoelectric " spark generator" button multiple times until you observe a pilot flame.[4]

Keep holding the gas valve knob down for about 2 minutes. At this time ( after 2 minutes ) you can use a multimeter to measures the output of the thermopile in DC millivolts (the part that sits in the pilot flame and has 2 electrical leads attached to the gas valve ). It should measure 325 MV or above with no load. If it doesn't measure 325 MV or above, replace the thermopile.