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Heat pumps
Heat pumps · Error codes · Danfoss
high-returnDanfoss · DHP-H

high-return on a Danfoss DHP-H: Alarm that indicates that high return temperature prevents the compressor's operation

Short answer

On a Danfoss heat pump, high-return means: Alarm that indicates that high return temperature prevents the compressor's operation. 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: Alarm that indicates that high return temperature prevents the compressor's operation.

Part involved: return line temperature.

Likely causes:

  • Return temperature above compressor limit (e.g. heat curve/hot water set too high, closed emitters, flow imbalance) - causes not tabulated in VMGFC302.

Is it safe?

Does the heat pump stop?Partly
SeverityFault — clears by itself when the condition goes
Engineer needed?Yes

The heat pump keeps running with some functions stopped.

Resetting itself: Yes, when the condition clears.

What you can check

  • Note the exact alarm text. The manual allows acknowledging by setting the operating mode to OFF and then back to the previous mode - do this once; if the alarm returns, leave it and call an engineer. Check the heating-system pressure gauge is in the range given in the user guide (Thermia/Danfoss: 1-1.5 bar when cold) - do not top up yourself unless you have been shown how; check radiator/underfloor valves and room thermostats are open.

What the engineer will check

  • Check heat curve/MAX settings, hot water stop temperature, emitter flow and bypass arrangements.

Who to ask for: heat pump engineer.

What you might notice

Sources

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026