high-pressure on a Danfoss DHP-M: Class A alarm. The heating circuit is the heat pump's high pressure circuit - check the circuit's level (pressure) and acknowledge
Short answer
On a Danfoss heat pump, high-pressure means: Class A alarm. The heating circuit is the heat pump's high pressure circuit - check the circuit's level (pressure) and acknowledge. 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: Class A alarm. The heating circuit is the heat pump's high pressure circuit - check the circuit's level (pressure) and acknowledge.
Part involved: high pressure switch.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Press the acknowledge button on the touchscreen (resets all alarms).
What you can check
- Check the heating-system pressure gauge is in the range given in the user guide (Thermia/Danfoss: 1-1.5 bar when cold) - do not top up yourself unless you have been shown how; check radiator/underfloor valves and room thermostats are open. Acknowledge once via the touchscreen; if it persists or recurs, call the installer. If an A-alarm cannot be acknowledged and hot water is needed, the guide allows selecting operating mode 'Auxiliary heater + service'.
What the engineer will check
- Pressure/flow checks on heating or brine side; refrigerant circuit checks.
Who to ask for: heat pump engineer.
Certification: F-Gas category I certificate (refrigerant circuit work).
What you might notice
Sources
- User Guide DHP-M (VUJSD302) ↗ · VUJSD302 · page pp.21-22 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026