fitting an outdoor water supply

[oops!!!]

I have fitted an outdoor water supply for my garden hose.
via a pipe inside the combi boiler in the kitchen.
It has worked perfectly well for a couple of years.
When the combi was on 24 hours there was no problem with the water flow to the outside hose.
Recently we changed the central heating from 24 hrs on, to the automatic on/off cycle and we have noticed that the water is now trickling through the outside tap when turned on
Now I am not sure if the change has affected the flow or is there a blockage in the pipe
When I take off the outside hose fitting and turn on the outside tap, water is trickling out and I hear a noise like air being blown into a balloon.
Hope you can understand my long winded query and
any help will be greatly appreciated.

[buildersmate]

Are you referring to the water feed that goes into a combi that allows you to repressurise the system back to about 1 bar if it falls? If you are, that supply is nothing more than an extension off your cold water mains feed, and there should be no problem using it to feed elsewhere, as you have done to supply the outside tap. What doesn't make sense is the recent change you have experienced. Please clarify if I am referred to the right water feed.

[oops!!!]

Yes mate you are referring to the right water feed.
But checking again today I have noticed that when I turn on the hot water or when the central heating kicks in ,there is a noise that sounds like air escaping from the outside vent of the boiler !!!