Heat pumps · Error codes · Trianco
E122Trianco
E122 on a Trianco heat pump: Abnormal Adjustment of Mixing Valve
Short answer
On a Trianco heat pump, E122 means: Abnormal Adjustment of Mixing Valve. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manual says: Abnormal Adjustment of Mixing Valve.
Part involved: water flow / water temperature.
Likely causes:
- Mixing valve is incorrectly connected.
- Mixing valve is damaged.
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 exact code shown on the controller (a photo helps) and report it to your installer or the manufacturer's service line.
- Check the heat pump's supply breaker/isolator at the consumer unit is on (do not open any casing).
- Check the heating system pressure gauge reading (if one is fitted) and tell your engineer if it is below the level set at commissioning; do not attempt to refill unless you have been shown how.
What the engineer will check
- Plug and unplug terminals.
- Replace the mixing valve.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer (manufacturer training recommended).
What you might notice
Sources
- Trianco Activair R290 High Temperature Indoor Air Source Heat Pump (3.2kW wall hung) - Installation Operation and Service Manual ↗ · 2026-08 · page 33 · Reviewed 23 September 2026
- Trianco Activair Pro Air Source Heat Pump (R290 6/12/17kW) - Installation Operation and Service Manual ↗ · 06/2026 · page 40 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026