F11
Aquacomfort Air Pressure Switch / Prover Fault

Heater shows F11; fan may run but ignition sequence does not start.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Blocked combustion air intake, Faulty air pressure switch, Disconnected or cracked pressure tubing, Blower not achieving proper speed

How to Fix / Troubleshooting

Safety first: Disconnect power before opening the heater cabinet.

  • Check intake and exhaust: Ensure both the combustion air intake and exhaust vent are clear of obstructions.
  • Inspect pressure tubing: Locate the small silicone or vinyl tube running from the blower housing to the air pressure switch. Check for cracks, kinks, or disconnections. Replace if brittle.
  • Test pressure switch: With power off, disconnect the wires from the switch and check continuity while gently applying suction or pressure to the tubing. The switch should change state. If it does not, replace the switch.
  • Verify blower operation: If the blower is weak or noisy, it may not be generating enough pressure to close the switch, requiring blower service.
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Repair Difficulty

Hard 4/5

Required Part

Air Pressure Switch
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