M
Mike Jackson
I had a call last year. There had been a fire in a flat and the FB had shut off the water to the whole building. When it was turned back on the basement flat had a very poor flow of hot water, it ran briefly then stopped. The previous 3 plumbers had turned up tried to get it going and declared that it must be a blockage and left. I turned up, checked the cistern for debris, found none and said it must be an airlock. Apparently the other guys had said this but changed their minds when they couldn't clear it. I got my highly expensive £35 Wickes wet vac out, put it on the bath tap and sucked. 30 seconds later, gurgle, gurgle splutter and they had a good flow of hot water.