Heat pumps · Error codes · Trianco
08Trianco · Activair (first generation) S300/S500/S800/S1200/S1300/S1800
08 on a Trianco Activair S300/S500/S800/S1200/S1300/S1800: Refrigerant pressure cutout #1
Short answer
On a Trianco heat pump, 08 means: Refrigerant pressure cutout #1. The heat pump stops until the fault clears or is reset.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Refrigerant pressure cutout #1.
Part involved: water flow / water temperature.
Likely causes:
- No water in appliance.
- Air lock.
- Impaired water flow.
- Faulty pump / stuck pump impeller.
- Cylinder sensor detecting incorrect temperature.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Unit automatically resets after refill/air removal (manual p.21).
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
- Refill system with water (filling guide p.2.
- flush air and refill.
- ensure pipework is clear and correctly sized.
- ensure pump is working and free a stuck impeller.
- ensure cylinder sensor is correctly positioned and cylinder flow/return correctly piped.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer (manufacturer training recommended).
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- Keeps stopping / cutting out on the Activair (first generation) S300/S500/S800/S1200/S1300/S1800: 1 report
Sources
- Trianco Activair Air-to-Water Air Source Heat Pump S300 & S500 - User, Installation, Commissioning & Servicing Instructions (224511) ↗ · 224511 · page 21 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026