I have an airlock in the hot water supply.
Local builder has tried switching the washing machine feed pipes, but our machine has only one feed! He's tried blocking the mixer taps to force the air back - no use.
I would like to know - if I turn off the mains water and drain the cold tank and the hot water tank completely, then refill, will this solve the problem?

Go to the most distanced plumbing fixture from water heater, turn hot and cold water ON and let it run for few several minutes...

Water system is a closed system under pressure. It is not so easy to get "air lock" in the system that would stay in one place and refused to move. What makes you think you have "air-lock" in your plumbing system ? What does it do ? Or what doesn't it do ? Please, explain.

Back to you

Milo

Milo,

Google "domestic hot water systems in the UK"