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Mitsubishi Ecodan fault 9

Water heating takes longer

Heat pump

What it means

Water heating time is extended beyond normal, which may be due to heat pump malfunction, booster/immersion heater trips, or reduced flow rate in the sanitary circuit.

Likely causes

  1. Heat pump not working
  2. Booster heater cut-out tripped
  3. Booster heater breaker (ECB1) tripped
  4. Booster heater thermal cut-out tripped and cannot be reset using manual reset button
  5. Immersion heater cut-out triggered
  6. Immersion heater breaker (ECB2) tripped
  7. Flow rate of the sanitary circuit may be reduced

Where to start

  1. Check heat pump - consult outdoor unit service manual
  2. Check booster heater thermostat and press reset button if safe (located on side of booster heater under white rubber cap)
  3. Check immersion heater thermostat and press reset button located on immersion heater boss if safe

The full answer, free

  • 16 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 55), 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 Mitsubishi manual for the Ecodan. Check the model on the data plate before you order parts.

Other Mitsubishi Ecodan fault codes