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Midea Heat pump fault HB

Repeated PP protection in heating/DHW mode

Heat pump

What it means

Triggered when PP fault occurs 3 times in heating/DHW mode. If Twout<7°C occurs during this period, the number of PP failures counted increases by one, accelerating the trigger of Hb.

Likely causes

  1. Repeated occurrence of PP fault (abnormal temperature difference between outlet and inlet water) in heating/DHW mode
  2. Twout dropping below 7°C increases PP failure count
  3. Low ambient temperature (T4<3°C) combined with low water-side temperature triggers freeze protection
  4. Water side temperature dropping below critical thresholds due to low flow, low ambient temperature, or system stoppage

Where to start

  1. Identify CN30 terminal block pins 1-10 (A, B, X/HA, Y/HB, E, T1, T2, E1, H1, H2)
  2. Confirm correct wiring of A, B, X/HA, Y/HB, E to external Modbus module terminals X1/HB, X2/HA, H1, H2
  3. Verify B-/A+/E connections to Modbus interface

The full answer, free

  • 19 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 137), 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 Midea manual for the Heat pump. Check the model on the data plate before you order parts.

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