Hot water coming out of cold tap

[TamHam]

I stripped out the downstairs bathroom yesterday which involved closing the main stop cock which I noticed was a wee bit stiff and that it was barely open.

When i turned the stop cock back on, the pressure seemed to be greater than before. In fact it flushed through a lot of gunk through the taps.

Since then the shower appears to be coming out colder but at a greater pressure and addition to this there is hot water coming out the bathroom tap.

Could this be because of the water pressure?

Any advice would be greatly appreciated.

 

[DaveHerns]

Is this in your upstairs bathroom ? Does it stay running hot? What sort of heating system have you got?

 

[TamHam]

It's a system boiler with a calorifier. Hot water coming out of the upstairs bathroom only.

 

[TamHam]

Runs cold after 10 seconds

 

[picasso]

One of your shower non return valves is probably stuck open.

 

[TCCHeating]

One of your shower non return valves is probably stuck open.

+1

 

[TamHam]

One of your shower non return valves is probably stuck open.

+1

What are the chances of that resolving itself?