Replace hot water washer tap

[Wulfgar]

Hello all.
I know this topic has endless threads but each one is different.
I am needing to change washer on downstairs hot tap. So I went to airing cupboard and turn the gate valve on the feed to the HW cylinder from the cold water tank in the attic. This is a Peglar valve and has a very short turn right to left. But the hot water does not stop flowing. Bizarre as no other pipes feed the cylinder.
18 months ago I had new WB system boiler fitted which is fully pumped and this replaced a CF Ideal standard gravity HW pumped CH. This was done by a competent engineer who left the HW system in place and just connected the boiler to the HW feed and return to the cylinder from the new boiler with diversionary valve/tank thermostat.
The Peglar valve has a very short turn right to left. I presume this is correct and not one you use to screw in tightly.
Any ideas? Thanks

 

[cross thread]

If it’s a standard gate valve it will be around 4 full turns to close

 

[terryplumb]

Bung the cold water cisterns outlet to the hot water cylinder,it sounds like the isolation valve isn't fully closing.

 

[Wulfgar]

Thank you all. Yes, the valve needed a bit of 'working' back and forward to get it moving al the way closed. It was very tight to start it at all. It does not need to touching for a long time so becomes very stiff. OI was a little wary of using brute force as that could lead to a worse situation.
Thanks