Heat pumps · Error codes · Hitachi
b1Hitachi
b1 on a Hitachi heat pump: Incorrect setting of address or refrigerant cycle number
Short answer
On a Hitachi heat pump, b1 means: Incorrect setting of address or refrigerant cycle number. 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: Incorrect setting of address or refrigerant cycle number.
Part involved: outdoor PCB address setting.
Likely causes:
- Over 64 indoor units set by number or indoor unit address.
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.
Resetting itself: no.
Manual reset: Correct setting then restart.
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.
- Call the installer - this is a commissioning/setting fault.
What the engineer will check
- Follow SMGB0146 section 6.7 troubleshooting flowchart for alarm b1.
- Check DIP switch capacity/model settings on indoor and outdoor PCBs.
- Check unit controller installer configuration.
Who to ask for: Commissioning engineer / MCS heat pump installer.
What you might notice
Sources
- Installation & Operation Manual - YUTAKI series and YUTAKI Cascade Controller (R410A series / R32 series) ↗ · PMML0510 rev.1 - 10/2019 · page p.149 (PDF p.160) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026