H06.53 on a Baxi HP60 / Baxi Assure HP55 High Temperature Monobloc ASHP: Tambiant air minimum The ambient air temperature is below the allowed minimum
Short answer
On a Baxi heat pump, H06.53 means: Tambiant air minimum The ambient air temperature is below the allowed minimum. The heat pump keeps running with some functions stopped.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Tambiant air minimum The ambient air temperature is below the allowed minimum.
Part involved: protection function.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | No |
The heat pump keeps running with some functions stopped.
Resetting itself: yes - system restarts automatically when the cause disappears (may run in degraded/back-up mode meanwhile).
Manual reset: not required once cause removed.
What you can check
- No action normally needed - the manual says the unit returns to normal operation automatically.
- Check the outdoor unit is not blocked by snow or ice.
What the engineer will check
- Diagnose per manufacturer service procedure (manual gives description only).
Who to ask for: heat pump engineer (controls / sensors).
Certification: Manufacturer-trained heat pump engineer.
What you might notice
Sources
- Installation, user and service manual - Indoor unit ASHP Control ↗ · 7887625 - v04 - 22072025 · page 130 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026