I've got combi boiler which is running fine. It heats and produces hot water from all taps apart from 1. If I open up all the other hot taps for a short period then turn them of, the issue tap works fine for a while. It then ends up as a trickle and eventually stops. That would indicate to me that there's no blockage in the pipework, yet my research shows that it's not really possible to get an airlock on a sealed system. If the boiler is happily supplying hot water at all of the other taps it seems to indicate the boiler is functioning properly. To my mind it only leaves the tap being faulty, but I don't understand why it seems to work ok after all the other taps have been opened for a while, in fact it works ok all the time provided the other taps are on. Is the answer a faulty tap, or am I missing something.