When noise, icing, cycling or lost comfort needs professional diagnosis. This guide explains the decision points without promising that one answer fits every property.

Repeated codes need context

Photograph the display, note weather and hot-water demand, and avoid repeated resets that erase useful clues.

Comfort changes can be system changes

A cold room may come from air, pressure, a valve, a control schedule or emitter balance rather than the outdoor unit.

Persistent ice is different from frost

Normal defrost should clear frost. A solid or recurring ice build-up with poor output needs investigation.

The practical next step

Use the guide to frame your questions, then ask for evidence that relates directly to this topic, the home and the proposed system. A measured assessment turns general information into a written decision you can compare.