I fit a 1.8b poitive head pump under a bath to supply a bath shower mixer.
The bathroom is approx 3m below the storage cistern which is in in the loft , the hot
Water cylinder is horizontal , on the same floor as the bathroom .
I am now finding , every so often there are airlocks to every hot tap.
What can I do to prevent air being drawn into the system.
The cold water storage cistern is not running dry.