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When pre-heating is enabled, the system will start to heat the room before the start of the heating period so the room is up to temperature at the start of the heating period. For example, if you set a heating period between 14:00 and 16:00 the system will start to heat the room at 13:00 so the zone has reached its set temperature at 14:00. When a zone is pre-heating due, the pre-heating symbol will be coloured to show why the zone is heating before the heating period has started.
<image of tile /zone details with preheating symbol highlighted>
When pre-heating is enabled there are a further 2 options:
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