Heat pumps · Error codes · Thermia
low-evap-temp-1Thermia · Atec
low-evap-temp-1 on a Thermia Atec: Evaporation temperature too low
Short answer
On a Thermia heat pump, low-evap-temp-1 means: Evaporation temperature too low. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Evaporation temperature too low.
Part involved: evaporation temperature.
Likely causes:
- Low evaporation temperature (icing, airflow restriction, low charge) - not tabulated. (causes from the equivalent Danfoss DHP-AQ service instructions VMGFJ202).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Set operating mode OFF then back to the desired mode.
What you can check
- Note the exact alarm text. Check the outdoor unit is not blocked by snow, ice, leaves or debris and that airflow around it is clear. Acknowledge once (operating mode OFF then back); if it remains, contact a service technician (user manual 086L0130 p.25).
What the engineer will check
- Check airflow, icing/defrost, superheat and charge.
Who to ask for: heat pump engineer.
Certification: F-Gas category I certificate (refrigerant circuit work).
What you might notice
Sources
- Service Instructions Atec (VIIFM102) - silo.tips copy ↗ · VIIFM102 · page p.10 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026