Hello Shaun, Ive investigated further. Both sides of the auto bypass are hot in all situations. I guess its set at the lowest pressure. Before this autobypass was fitted (a few months ago with the new boiler), it was simply a pipe...
about 9 months ago, my glowworm boiler was replaced by a new worcester bosch unit. At the same time, the system was flushed, fernox protection was added, new 3 way valve and the bypass pipe with gate valve was replaced by a auto bypass...