DIY Projects - Airlocks
Air trapped in the system may cause a gurgling and hissing noise in the pipes and the water may splutter. Usually the systems affected are indirect where the water pressure is low.
The easiest way to remove an airlock is to attach a piece of hose between the affected tap and a tap that is supplied direct from the mains, securing the pipe with hose clips. First turn on the affected tap and then the tap supplied direct from the mains, leave them both on for 30 seconds and then close the taps, close the mains supplied tap first. Check if the airlock has cleared, if not repeat the process, it may take several goes to clear the airlock.

Always seek the cause of recurring airlocks. A common problem is that the cold water storage tank is not filling up as quickly as it is being drained. To check this, watch the tank while someone else fills the bath to see if the tank empties before the bath fills which would draw air into the system. If this is the case it may be that a stopcock is not open enough or the float valve on the tank is faulty.