We have an indirect hot water system in a bungalow. The previous owner reports that for many years an air lock has developed in the hot water system. This prevents water flowing to the kitchen sink of hand basins in the bathroom or utility room. This can be remedied in one of two ways. The first is to simply run the hot water tap in the bath. When it is turned on it flows slowly for perhaps 15 - 20 seconds then 'splurts' out a combination of hot water and air. After 5 or 6 such 'splurts' the hot water flows freely from any tap in the bungalow. The second way of sorting the problem is to block the kitchen sink mixer tap with your thumb. Then turn on the hot water followed by the cold water. Because the water cannot escape in the normal way, the cold water passes back up the hot water pipes and pushes out the air through the hot water tank. It is possible to hear the air escaping through the hot water tank in the loft. Once this has been done the water flows freely from all taps.
Until recently this problem only arose after a bath had been run and the hot water tank emptied. However, lately the problem has increased and it is necessary to purge the system several times a day.
Any suggestions as to where to start with this problem would be greatfully received.
Cheers
Bill