Heat pumps · Error codes · Trianco
Er23Trianco · Activair R32 (S700 / S1200 - FG 9007 / FG 9012)
Er23 on a Trianco Activair R32: Low outlet water temperature protection under cooling mode
Short answer
On a Trianco heat pump, Er23 means: Low outlet water temperature protection under cooling mode. 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: Low outlet water temperature protection under cooling mode.
Part involved: water flow / water temperature.
Likely causes:
- Inadequate water flow rate.
- Low inlet water temp.
- Unreasonable anti-freeze protection temp setting.
- Main PCB damaged.
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 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
- Check the water filter and water circuit (no block).
- Adjust the setting temp to normal working range.
- Adjust to right anti-freeze protection temp setting.
- Replace the main PCB.
Who to ask for: heating / hydraulics.
Certification: Competent heating engineer (manufacturer training recommended).
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, 21 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026