Heat pumps · Error codes · Ideal Heating
127Ideal Heating · Logic Air
127 on an Ideal Heating Logic Air: Anti-Legionella Temp' Fault
Short answer
On an Ideal Heating heat pump, 127 means: Anti-Legionella Temp' Fault. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Anti-Legionella Temp' Fault.
Part involved: immersion heater / contactor.
Likely causes:
- No 230 V to indoor unit contactor L In; contactor not switching (RVS21 wiring/PCB); no 230 V at immersion heater; immersion thermostat not at maximum; failed immersion heater.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
What you can check
- Note the code or fault message shown on the controller/Halo and when it appeared; check the heat pump's isolator and consumer-unit breaker are on.
What the engineer will check
- Check 230 Vac at contactor L In and L Out using relay test; check wiring RVS21-contactor; set immersion thermostat to max; replace immersion heater.
Who to ask for: Heat pump / heating controls engineer.
Certification: Electrical work by competent person.
What you might notice
Sources
- Logic Air Monobloc Heat Pump System - Installation & Maintenance (UIN 241428 A03) ↗ · UIN 241428 A03 · page 81 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026