H2 on a Hisense Hi-Therma Monobloc: Wired Remote Controller and Master Controller transmission alarm
Short answer
On a Hisense heat pump, H2 means: Wired Remote Controller and Master Controller transmission alarm. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Wired Remote Controller and Master Controller transmission alarm.
Part involved: PCB / communication wiring / settings.
When it shows: Wired Remote Controller is configured as room thermostat but no Wired Remote Controller is detected.
Likely causes:
- Wired Remote Controller is configured as room thermostat but no Wired Remote Controller is detected.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
What you can check
- Note the code shown on the controller and the unit model numbers (on the rating plate label) before contacting your installer.
- Check the heat pump's breaker/isolator at the consumer unit is on; do not open any casing.
- Check the controller display is lit; a single power cycle at the isolator may be tried only if your installer or manual allows it.
- Check controller mode/temperature/timer settings have not been changed; setup (DIP switch) errors need the installer.
What the engineer will check
- Follow the handbook alarm-code flowchart (O.U. section from printed p.335, I.U. section from viewer p.383).
- Check communication wiring, terminals and fuses between units/controller.
- Check DIP/rotary switch and address settings.
- Replace PCB if the fault persists per the flowchart.
Who to ask for: Heat pump engineer.
Certification: Heat pump installer competence; F-gas / flammable-refrigerant (R290/R32) handling competence for any refrigerant-circuit work.
What you might notice
Sources
- Air-to-Water Heat Pump Technical, Installation and Service Handbook - Hi-Therma Series (TCY12021017E) ↗ · TCY12021017E · page p.334 (printed; ManualsLib viewer p.355) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026