H7
AstralPool Water Temperature Sensor (NTC) Fault

Heater displays H7 and will not start; no ignition attempt is heard.

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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

Failed AstralPool NTC sensor, Broken or shorted sensor wiring, Corroded connector at control board, Control board input fault

How to Fix / Troubleshooting

Safety first: Turn off power before accessing the control compartment.

  • Locate the NTC sensor: It is usually threaded into the water manifold or attached with a clip. Inspect the sensor body and wiring harness.
  • Check connections: Ensure the sensor plug is fully seated on the main control board and that there is no corrosion or water ingress at the connector.
  • Visual inspection of cable: Look for cuts, rodent damage, or pinched sections along the sensor cable.
  • Basic resistance check (if you have a meter): With power off and sensor disconnected, measure resistance across the sensor leads. Compare to AstralPool’s temperature/resistance chart. An open or shorted reading indicates a bad sensor.

Replace the NTC sensor if defective. If a new sensor does not clear H7, the control board may be faulty.

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Repair Difficulty

Medium 3/5

Required Part

AstralPool Water Temperature Sensor (NTC)
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