52 on a Viessmann Vitotronic 200: Cylinder sensor bottom: If only the lower cylinder temperature sensor is present: No DHW heating; If an additional upper temperature sensor is installed: DHW heating possible, switched on and off …
Short answer
On a Viessmann heat pump, 52 means: Cylinder sensor bottom: If only the lower cylinder temperature sensor is present: No DHW heating; If an additional upper temperature sensor is installed: DHW heating possible, switched on and off …. 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: Cylinder sensor bottom: If only the lower cylinder temperature sensor is present: No DHW heating; If an additional upper temperature sensor is installed: DHW heating possible, switched on and off ….
Part involved: Cylinder sensor bottom.
When it shows: If only the lower cylinder temperature sensor is present: No DHW heating; If an additional upper temperature sensor is installed: DHW heating possible, switched on and off via this sensor.
Likely causes:
- Short circuit, bottom cylinder temperature sensor.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
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: Acknowledge with OK on the programming unit (user level permitted per 5817913 p.56-57) after the cause is remedied.
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 heat pump breaker/isolator in the consumer unit is ON (do not repeatedly reset a breaker or RCD that keeps tripping).
What the engineer will check
- Check resistance value (NTC 10 k Ω) at plug F7 or at terminals X25.7/X25.8: See "Controller and sensor PCB".
Who to ask for: Viessmann-trained heat pump installer/service engineer.
What you might notice
Sources
- Service instructions Vitotronic 200 type WO1C heat pump control unit (air/water split & monobloc, brine/water) (6150133, 2023-07) ↗ · 6150133 VSA00004 · page 92 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026