10048 on a Stiebel Eltron WPM heat pump manager / WPMsystem: The low pressure limiter has been triggered in cooling operation
Short answer
On a Stiebel Eltron heat pump, 10048 means: The low pressure limiter has been triggered in cooling operation. 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: The low pressure limiter has been triggered in cooling operation.
Part involved: compressor / expansion valve / pressure switches.
When it shows: The low pressure limiter has been triggered in cooling operation.
Likely causes:
- Non-return valve leaks. Expansion valve not working correctly.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: yes - heat pump restarts after idle time (~10-12 min); locks out after 5 faults in 2 h run.
Manual reset: after 5 faults in 2 h: IWS/WPM reset.
What you can check
- Do NOT bleed radiators (Stiebel R290 manual: possible refrigerant ingress into heating water); contact your installer/service department.
- Read and note the full message code and time from the WPM display (DIAGNOSIS / NOTIFICATIONLIST if accessible without a code).
- Check the heat pump and controller circuit breakers/isolators at the consumer unit are on.
- Check the heating system pressure gauge reading is in the normal range stated by your installer.
- Check the outdoor unit air intake/discharge is not blocked by leaves, snow or ice (air source units).
What the engineer will check
- Non-return valve leaks. Expansion valve not working correctly.
Who to ask for: F-gas/refrigeration-qualified heat pump engineer (R290/A3 flammable-refrigerant competence for R290 models).
Certification: F-gas certification for fluorinated refrigerants (R410A/R454C); flammable refrigerant (R290) handling training for R290 models.
What you might notice
Sources
- WPM notification list (WPM V2.9) - multilingual; English section pp.15-26 (DOC-00081866) ↗ · WPM V2.9 · page 15 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026