E19 on a Trianco heat pump: Primary Antifreezing Prot. In Winter
Short answer
On a Trianco heat pump, E19 means: Primary Antifreezing Prot. In Winter. The manual does not say whether the heat pump stops. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 4 sources
What it means
On the Activair Commercial R290 50kW (FG9550)
The manual says: Primary Antifreezing Prot. In Winter.
Part involved: ambient / water temperature protection logic.
Likely causes:
- Excessively low environment temperature.
On the Activair High Temperature R290 (5/9/15/22kW)
The manual says: Primary Anti-freezing Protection.
Part involved: ambient / water temperature protection logic.
Likely causes:
- Ambient temp <=0C and water inlet between A04-2C and A04 (alternative printed condition: 2C <= water inlet <= 4C).
On the Activair R290 Indoor (3.2kW wall hung / 5kW floor standing)
The manual says: Primary Anti-freezing Fault.
Part involved: ambient / water temperature protection logic.
Likely causes:
- The ambient temp. is low.
On the Activair Pro (AI) R290 6/12/17kW
The manual says: Primary Anti-freezing Fault.
Part involved: ambient / water temperature protection logic.
Likely causes:
- The ambient temp. is low.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
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 snow, ice build-up or debris.
- Leave the heat pump powered: frost protection needs a permanent electricity supply.
What the engineer will check
On the Activair Commercial R290 50kW (FG9550)
- The environment temperature is more than 4C (clears when ambient rises).
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer.
On the Activair High Temperature R290 (5/9/15/22kW)
- Frost protection in winter.
- Once the water temperature rises to A04+4C (or 8C) or the ambient temp is higher than 1C, the error code disappears.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer.
On the Activair R290 Indoor (3.2kW wall hung / 5kW floor standing)
- Check the ambient temp value.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer.
On the Activair Pro (AI) R290 6/12/17kW
- Check the ambient temp value.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer.
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
- Trianco Activair High Temperature Air Source Heat Pump (R290 5/9/15/22kW) - Installation Operation and Service Manual ↗ · November 2024 (PDF regenerated 2026-08) · page 34 · Reviewed 23 September 2026
- 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