Heat pumps · Error codes · Trianco
E221Trianco · Activair Commercial R290 50kW (FG9550)
E221 on a Trianco Activair Commercial R290 50kW: Syst2: 4-Way Valve Abnormal Switch
Short answer
On a Trianco heat pump, E221 means: Syst2: 4-Way Valve Abnormal Switch. 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: Syst2: 4-Way Valve Abnormal Switch.
Part involved: pressure switch / compressor discharge-suction.
Likely causes:
- The system 4-way valve switching failure.
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 outdoor unit is not blocked by debris/snow and has its required clearances.
What the engineer will check
- Check if the state of the 4-way valve switching direction is the desired state.
Who to ask for: refrigeration.
Certification: F-gas certified refrigeration engineer (REFCOM or equivalent).
What you might notice
Sources
- Trianco Activair Commercial High Temperature Air Source Heat Pump (R290 50kW FG9550) - Installation Operation and Service Manual ↗ · 2024-10 · page 39 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026