Faulty Stop Tap - drop in pressure

[geocalico]

I recently installed a new kitchen tap, isolating the cold supply from the main incoming stop tap and the hot supply at the combi boiler. When I turned the stop tap back on it didn´t engage as expected, rather nothing happened when I turned it a small amount, then I heard a bang before hearing water flowing through.

Now when someone is having a shower (for example), and someone turns on the cold tap or flushes the toilet, the shower looses considerable pressure. Shower is connected to the combi.

What might I have done for this to happen. Could the stop tap jumper/washer be stuck half-open meaning I´m not getting full pressure to all appliances.

Can just the tap jumper/washer be replaced or is it easier to replace the entire stop tap

Cheers

 

[AGAS]

Did you get the same cold pressure on kitchen tap when you turned the stop tap back on.

 

[geocalico]

Yes, same pressure at the cold kitchen tap

 

[HERTS P&D]

Take out the stop cock and fit a full bore lever valve.

http://www.screwfix.com/p/full-bore-lever-ball-valve-15mm/80413

Andy

 

[jackthom]

Have you tried closing the stop tap and reopening it a few times while one of the cold taps is turned on full.
If it is sticking that might help shake things up.