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Elizabeth WilliamsAug 17, 2025
What to do if my Hayward Heater shows 'Ignition Failure'?
- GGary SmithAug 17, 2025
If your Hayward Heater is experiencing ignition failure, you should inspect the ignition system for faults.
What to do if my Hayward Heater shows 'Ignition Failure'?
If your Hayward Heater is experiencing ignition failure, you should inspect the ignition system for faults.
What to do if my Hayward H400FDN Heater displays a 'Communication Error Between Control Module and Display Interface Assembly'?
If your Hayward Heater shows a communication error between the control module and the display interface assembly, verify the connections between these components.
What to do if my Hayward H400FDN Heater displays 'Temperature Sensor (thermistor) input failure'?
If your Hayward Heater shows a 'Temperature Sensor (thermistor) input failure', check the temperature sensor and replace it if necessary.
What to do if my Hayward H400FDN shows 'Ignitor Circuit Open'?
If your Hayward Heater displays 'Ignitor Circuit Open', check the ignitor circuit for continuity.
What to do if my Hayward Heater indicates 'Keypad failure'?
If your Hayward Heater indicates a 'Keypad failure', the solution is to replace the keypad.
What to do if my Hayward Heater displays 'Maximum return water temperature exceeded and / or rapid water temperature rise'?
If your Hayward Heater displays 'Maximum return water temperature exceeded and / or rapid water temperature rise', check the water temperature sensors and system settings.
What to do if my Hayward H400FDN shows 'Flame present with Gas Valve not energized'?
If your Hayward Heater shows 'Flame present with Gas Valve not energized', check the gas valve and ignition system.
What to do if my Hayward H400FDN displays 'Voltage polarity reversed, low voltage detected'?
If your Hayward Heater displays 'Voltage polarity reversed, low voltage detected', correct the polarity and ensure proper voltage is supplied.
What to do if my Hayward Heater shows 'Water Pressure Switch, Vent Pressure Switch, or Temperature Limit Switch Fault'?
If your Hayward Heater indicates 'Water Pressure Switch, Vent Pressure Switch, or Temperature Limit Switch Fault', inspect all associated switches for proper operation.
What to do if my Hayward Heater displays 'Blower Vacuum Switch open'?
If your Hayward Heater displays 'Blower Vacuum Switch open', inspect the blower vacuum switch for faults.
General| Type | Natural Gas |
|---|---|
| BTU Input | 400, 000 BTU |
| Pool Type | In-ground |
| Heat Exchanger | Cupro Nickel |
| Voltage | 120V |
| Efficiency | 84% |
| Water Flow Rate | 40-120 GPM |
| Inlet/Outlet Size | 2 in |
| Ignition | Electronic |
Essential safety information and warnings for operating the heater.
Describes the normal and failure-to-light operating sequences for the UHS heater.
Details on how to connect power and gas supply to the heater unit.
Step-by-step instructions for specific heater operations and adjustments.
List of diagnostic codes and associated replacement part numbers.
Step-by-step troubleshooting for common issues like no power, open fuses, and service LED codes.
Details on heat exchanger flow requirements, inspection, and failure causes.
Visual representations of the heater's electrical connections and components.
