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Grant Aerona R32 fault E4

Outgoing water temp. sensor error

Heat pump

What it means

Fault in the outgoing water temperature sensor.

Likely causes

  1. Faulty outgoing water temperature sensor
  2. Thermal store set point reached (normal stop)
  3. Outgoing water temperature reaching protection limit (abnormal/protective stop)
  4. Low room air temperature
  5. Low outdoor ambient air temperature
  6. Low flow water temperature

Where to start

  1. Check the resistance by tester
  2. Verify pump activates for Time ON period set by Parameter 4201
  3. Check water temperature detection occurs 5 seconds before end of cycle

The full answer, free

  • 32 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 57), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Grant manual for the Aerona R32. Check the model on the data plate before you order parts.

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