Heat pumps · Error codes · Trianco
T5STrianco · Activair Pro (AI) R290 6/12/17kW
T5S on a Trianco Activair Pro R290 6/12/17kW: Cooling Not Allowed Due to Large Temperature Difference Between Indoor and Outdoor Temperature
Short answer
On a Trianco heat pump, T5S means: Cooling Not Allowed Due to Large Temperature Difference Between Indoor and Outdoor Temperature. The manual does not say whether the heat pump stops.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Cooling Not Allowed Due to Large Temperature Difference Between Indoor and Outdoor Temperature.
Part involved: controller configuration / service.
Likely causes:
- When dew point control is enabled and outdoor temperature is less than indoor temperature minus DP3, cooling is temporarily disabled.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Warning |
| Engineer needed? | No |
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).
What the engineer will check
- Wait - the fault clears automatically.
- Adjust parameter DP.
- Disable dew point control (DP1 =.
Who to ask for: heat pump commissioning.
Certification: Manufacturer-trained commissioning engineer.
Sources
- Trianco Activair Pro Air Source Heat Pump (R290 6/12/17kW) - Installation Operation and Service Manual ↗ · 06/2026 · page 41 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026