Heat pumps · Error codes · Kronoterm
Max-dTKronoterm · TERMOTRONIC-controlled heat pumps (legacy WP / WPL / WPLV water-water, brine-water, air-water)
Max-dT on a Kronoterm TERMOTRONIC-controlled heat pumps: Temperature difference between supply and return too high
Short answer
On a Kronoterm heat pump, Max-dT means: Temperature difference between supply and return too high. 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: Temperature difference between supply and return too high.
Part involved: flow.
Likely causes:
- Disturbance in the flow.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: After fixing the cause restart by holding ENTER for 3 s.
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, clean strainer, refill/vent.
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, 59 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026