Heat pumps · Error codes · Danfoss
no-of-tries-x-5Danfoss · DHP-AQ
no-of-tries-x-5 on a Danfoss DHP-AQ: Circulation pump is jammed. Start attempt made
Short answer
On a Danfoss heat pump, no-of-tries-x-5 means: Circulation pump is jammed. Start attempt made. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Circulation pump is jammed. Start attempt made.
Part involved: circulation pump.
Likely causes:
- Circulation pump jammed or air-locked; integrated shake function attempts up to 5 restarts (X = 1...5).
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Information only |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
What you can check
- Note the exact alarm text. 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. The manual allows acknowledging by setting operating mode OFF then back once; if the alarm returns, call an engineer.
What the engineer will check
- Vent heating system and TWS coil; cut power, manually run pump; replace if recurring.
Who to ask for: heat pump engineer.
What you might notice
Sources
- Service Instructions DHP-AQ (VMGFJ202) ↗ · VMGFJ202 · page p.10; p.19 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026