A tap which doesn’t supply water when switched could be air locked. To resolve this, attach a length of hose to the tap and connect the other end to a working tap. In most cases this will be the cold tap on the kitchen sink. Open both taps to allow the pressure of the mains water to force the air back out of the pipes. Leave to act for several minutes and then turn off at the air locked tap first. Barbican Plumbers have the necessary skills required.It is possible that you will need to do this a few times to release the air and allow water to flow correctly. When this is done, undo the hose from the higher of the taps, then releasing the lower and allowing the water in the hose to drain into the sink
Air lock at more than one tap.
If more than one tap is air locked, you should always clear from the lowest tap first. Using cold water pipes from the loft cistern, it may also be possible to blow out the airlock if the above method does not work. Put a length of hose into the outlet pipe in the tank. Open the tap at the other end, blowing through the pipework to dislodge the airlock.
Draining down to remove an air lock.
Another and probably final method is to drain the system down. Isolate the water feed and open all the taps to drain the water. Close the taps to about a three quarters closed. Turn the water supply back on. Adjust them all until a light, even flow of water is achieved. Now go round opening them one by one to the half-open position, starting with the lowest and working upwards. Repeat at the three quarters open position. Once all air has been discharged, turn all taps off to a point where there is only a minimal flow. Broadgate Plumbers carry out this work fully guaranteed.