1021 on an Alpha Heating Innovation Alpha E-Tec Hybrid: High pressure error: Outdoor unit evaporator/condenser fault (evaporator temperature below 0°C or condenser temperature >= 59.5°C)
Short answer
On an Alpha Heating Innovation heat pump, 1021 means: High pressure error: Outdoor unit evaporator/condenser fault (evaporator temperature below 0°C or condenser temperature >= 59.5°C). 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: High pressure error: Outdoor unit evaporator/condenser fault (evaporator temperature below 0°C or condenser temperature >= 59.5°C).
Part involved: E-Tec EHP outdoor unit.
Likely causes:
- Check evaporator fins clean and clear; condensate drainage clear; freezing/ice build-up; compressor pipes for leaks; all heat pump sensors. EHP manual: ensure minimum flow rate to avoid high pressure error (1021).
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 code and any text shown on the display/controller.
- Check the heat pump isolator and consumer-unit breaker are on.
- Check the outdoor unit is not blocked by debris, snow or leaves.
What the engineer will check
- Check evaporator fins clean and clear.
- condensate drainage clear.
- freezing/ice build-up.
- compressor pipes for leaks.
- all heat pump sensors. EHP manual: ensure minimum flow rate to avoid high pressure error (1021).
Who to ask for: heat pump engineer.
Certification: F-gas certified engineer (refrigerant circuit).
Sources
- Alpha E-Tec Hybrid - Installation Instructions (package, 06-23) ↗ · E-Tec Hybrid package instructions 06-23 · page 39 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026