Evening I have a Client that is contstantly getting air locks in her DHWS I have been around a few times and blown cold mains pressure up her hot pipe which has knocked the air lock out which works for a while but then the problem appears again a week or so later, its a 3 story house with kitchen on ground floor, bathroom on 1st floor plus another shower room on the top floor. the air locks only occur in the kitchen sink and 2nd floor. she has a conventonal boiler with a HWSV, I've got a lot of ideas of what I should do to clear this but have any of you lot come across this and point me in the direction of the correct solution rather than going through the motions?