Heat pumps · Error codes · Kronoterm
Caution-flowKronoterm · TERMOTRONIC-controlled heat pumps (legacy WP / WPL / WPLV water-water, brine-water, air-water)
Caution-flow on a Kronoterm TERMOTRONIC-controlled heat pumps: Flow switch not closed - no or insufficient water flow; after 120 s device enters compressor protection (Standby) and retries
Short answer
On a Kronoterm heat pump, Caution-flow means: Flow switch not closed - no or insufficient water flow; after 120 s device enters compressor protection (Standby) and retries. 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: Flow switch not closed - no or insufficient water flow; after 120 s device enters compressor protection (Standby) and retries.
Part involved: flow switch.
Likely causes:
- No or insufficient water flow.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
What you can check
- Note the exact message shown on the TERMOTRONIC display.
- Check the heating system pressure gauge reading.
What the engineer will check
- Check pump, valves, strainer, flow switch.
Who to ask for: heat pump engineer.
What you might notice
Sources
- KRONOTERM Owner's manual for heat pumps water-water, brine-water and air-water (TERMOTRONIC controller), Id 17-16-19-2972-05 ↗ · 17-16-19-2972-05 · page 52 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026