Intermittent hot water after turning off stop cock

[sparky3659]

Hi all.

I live in a new build, and have recently had some plumbing work to install an insinkerator in the kitchen sink. Some of the copper piping needed moving to do this, so the mains water was isolated under the sink in order to do so.

However, ever since then (and only occasionally) I have sometimes found no hot water out of some of the taps upstairs. The kids will complain about cold showers, yet when I run a different tap I get hot water after a few seconds, so I know we have hot water- it just doesn't come out of some of the taps sometimes. Could this be air in the system, and if so, is this a fix I can attempt myself?

We have a hot water cylinder fed by a Greenstar 24i condensing boiler.

 

[CountryFan]

Does the water not actually run or do you get water but it's cold? If the former then there could be detritus on the float valve seating.

 

[sparky3659]

water runs, but just freezing cold. But then I go to a sink in an adjacent room and it gets hot water. Then the original tap will then get hot water

 

[CountryFan]

I wonder if the pipes got crossed?