Heat pumps · Error codes · Danfoss
11Danfoss · DHP-AT
11 on a Danfoss DHP-AT: Low pressure protection
Short answer
On a Danfoss heat pump, 11 means: Low pressure protection. 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: Low pressure protection.
Part involved: Low pressure protection.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Note the 2-digit code. Check the outdoor unit is not blocked by snow, ice, leaves or debris and that airflow around it is clear. If the code persists, call an engineer.
What the engineer will check
- Low pressure switch trip (p.17): check airflow/icing, fan (fan thermal protector can cause HP/LP alarms), charge, leak test.
Who to ask for: heat pump engineer.
Certification: F-Gas category I certificate (refrigerant circuit work).
What you might notice
Sources
- Installation Guide DHP-AT - Installation and service manual (VMGFI302 / AN089486453198) ↗ · VMGFI302 · page p.32 (section 10.1.1); safety functions pp.16-17 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026