Heat pumps · Error codes · Trianco
Er04Trianco · Activair R32 (S700 / S1200 - FG 9007 / FG 9012)
Er04 on a Trianco Activair R32: Anti-freeze protection in winter
Short answer
On a Trianco heat pump, Er04 means: Anti-freeze protection in winter. The manual does not say whether the heat pump stops.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Anti-freeze protection in winter.
Part involved: ambient / water temperature protection logic.
Likely causes:
- This function occurs when ambient temperature is too 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
- No action needed.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer.
What you might notice
Sources
- Trianco Activair Air Source Heat Pump S700, S1200 - Installation and Service Manual (R32, FG 9007 / FG 9012) ↗ · 2022-04 issue · page 11, 20 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026