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Mitsubishi Ecodan fault 8

Cold water at tap

Heat pump

What it means

Water at the tap is cold instead of hot, with multiple possible causes ranging from hot water run-out and mode settings to heat pump, booster heater, immersion heater, and 3-way valve faults.

Likely causes

  1. Outdoor unit abnormal stop
  2. Hot water run out
  3. Prohibit, schedule timer or holiday mode selected
  4. Heat pump not working
  5. Booster heater cut-out tripped
  6. Earth leakage circuit breaker for booster heater breaker (ECB1) tripped
  7. Booster heater thermal cut-out tripped and cannot be reset using manual reset button
  8. Immersion heater cut-out tripped
  9. Immersion heater breaker (ECB2) tripped
  10. 3-way valve fault
  11. Immersion heater degradation causing earth leakage, triggering circuit breaker (heater always OFF)
  12. Water circulation pump wear leading to pump failure

Where to start

  1. Check for error code and contact number displayed alternately on remote controller
  2. Confirm DIP SW2-5 is ON to enable backup operation
  3. Ensure DHW mode is operating and wait for DHW tank to re-heat

The full answer, free

  • 37 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 54), 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