DB on a Viessmann Vitotronic 200: Refrig. circ (SHD) 2: Compressor heat pump stage 2 stops
Short answer
On a Viessmann heat pump, DB means: Refrig. circ (SHD) 2: Compressor heat pump stage 2 stops. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Refrig. circ (SHD) 2: Compressor heat pump stage 2 stops.
Part involved: Refrig. circ (SHD) 2.
When it shows: Compressor heat pump stage 2 stops.
Likely causes:
- Fault, refrigerant circuit, heat pump stage 2 (if installed):.
- Safety high pressure switch has responded.
- Compressor motor overload relay (thermal relay) has responded.
- Start-up resistor (Klixon) temperature switch has responded.
- Separate compressor motor overload relay (if installed) has responded.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: Not stated per code; Vitotronic messages remain until the cause is removed and are acknowledged with OK (6150133 p.82). Unremedied acknowledged faults are redisplayed the following day.
Manual reset: Measure text: "After removing the fault, switch the appliance first off and then on again.".
What you can check
- Note the 2-character message code and message text shown on the Vitotronic 200 display (press OK for details) and give them to your heating contractor (operating instructions 5817913 p.56).
- You may acknowledge the message once with OK as described in the Vitotronic 200 operating instructions; if it reappears, do not keep acknowledging it - call your contractor.
- Check the heating system pressure gauge reading and report a low reading to your contractor; make sure the filling loop is closed.
What the engineer will check
- Check flow and return temperature sensors in primary and secondary circuits.
- Check primary and secondary circuits for pressure and flow rate (see also message "A9 Heat pump").
- Have heat pump checked by a refrigeration engineer. The switching signal of the high pressure switch can be checked at terminals 214.2, 214.4 (see "Main ….
Who to ask for: Viessmann-trained heat pump engineer with F-gas refrigeration certification.
Certification: F-gas certificate (UK F-gas Regulations; Viessmann: refrigerant work by authorised refrigeration engineers only).
Sources
- Service instructions Vitotronic 200 WO1C (5790974 GB, 2023-09) – brine/water & split variants ↗ · 5790974 VSA00002 · page 90 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026