An amended sketch of my heating system. The overflow/expansion and refill were labelled the wrong way around on my pipes so the previous sketch was wrong.<br><br>a basic sketch of my central heating system.<br><br>The colour coding of the pipes relates to a posted question<br><br>Red: hot water system working fine<br>Purple: I can draw hot water off here without a problem<br>Blue: The problem effects whole CH system (and is not in purple or red pipes) therefore must be here.
