Problem
Defrosting is a normal part of air-to-water and air-to-air units. The question is frequency and duration — too-frequent defrosting eats into the energy meant for heating.
In damp 0 to +3 °C weather, defrosting every 40–90 minutes is typical. Defrosting every 20 minutes or constant ice buildup under the base is reason to check further.
Free airspace around the outdoor unit, fin cleanliness, condensate drain function, and placement relative to snow. These are safe checks an owner can do themselves.
The flow temperature can briefly drop. In a well-set-up system this isn't noticeable.
Protection from snow helps, but airflow must not be obstructed. We recommend leaving enough space around the unit.
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