Heat pumps · Error codes · Hitachi
71Hitachi · Yutaki S (split air-to-water)
71 on a Hitachi Yutaki S: Water pump feedback alarm
Short answer
On a Hitachi heat pump, 71 means: Water pump feedback 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: Water pump feedback alarm.
Likely causes:
- No feedback signal from the water pump.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
No need to switch off — call an engineer if it comes back.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Read and note the alarm code and any retry code (e.g. P70) shown on the unit controller.
- Check the heat pump supply breaker/isolator at the consumer unit is ON.
- Restart once via the unit controller (or switch off/on at the isolator) - the manual states the unit must be stopped to release most alarms; if the code returns, call an engineer.
- Check the system pressure gauge on the indoor unit (Yutaki S / S Combi have a factory manometer; Yutaki M uses a field-fitted gauge) - Hitachi gives about 1.5-2.0 bar as normal and it must stay above 1 bar and below 3 bar.
- Check the filling loop is closed.
What the engineer will check
- Follow SMGB0146 section 6.7 troubleshooting flowchart for alarm 71.
- Check water pump operation and fuse, pump feedback.
- Check all circuit valves open, clean strainers/filters (Filter+ valve).
- Check water pressure > 1 bar, bleed air, check flow and pressure switch/sensor continuity.
- Check heater contactors, water thermistors and minimum system water volume.
Who to ask for: Heating engineer / MCS heat pump installer.
Certification: G3 unvented qualification where a DHW cylinder is involved.
What you might notice
Sources
- YUTAKI S Series Technical Catalogue (RWM-(H)FSN3E indoor units; RAS-H(V)RNME-AF / RAS-HVRN2 outdoor units) ↗ · TCGB0070 rev.3 - 04/2012 · page p.163 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026