lack of water

[greenfingers1966]

Hi my cold water in the bathroom was running fine all of a sudden there was very little water coming out of the tap even when turned fully on. I have no radiators, only a rayburn which heats the hot water, there is a pipe going from the rayburn straight to the hot water cylinder. The rayburn is only lit up when the weather turns cold. I have a shower and no water comes out of that at all either. On the odd occassion air seems to be trying to come out of the cold water tap, I turn it on the water will come out spitting and spurting then go back to comig out very slowly. My water pressure down stairs is as it had always been. Has anyone got any suggestions.
Many thanks

 

[Congreave]

Does the hot draw any water?

 

[algeep]

is the water in the bathroom fed by header tank in the attic as the feed valve could be blocked so not filling the tank to feed the bathroom