Hot water shut off?

[joelpeyton]

Why is it that when I turn my mains stop cock off, then shut off the cold water supply to my hot water cylinder that I still get a small amount of hot water coming through my hot taps.

I thought the above process was meant to isolate the hot water, even after two hours there was still hot water coming through the taps.

Mmm

 

[Hugh Jaleak]

Assuming you've a tank fed system, the gate valve from the cold storage tank is probably letting by. (They are prone to this after a while.) As the hot cylinder is fed from the tank you have the contents of this tank, (usually about 25 gallons) that is still getting (albeit now slowly) into the cylinder and thus to the hot taps.

 

[JPC]

to isolate the hot u only need to turn off the later. i can only guess that it does not close off fully , its normally a gate valve

 

[landyandy]

Sounds like the valve is passing.

 

[joelpeyton]

OK cool, GV letting by, but if I need to work on my hot water pipes, this means that i will have to drain down the CWSC?

If I turn off the mains stop cock, then run the hot taps persumely this would be the best way of doing it? Its a massive tank, it could take a life time!!!

 

[landyandy]

Change the gate valve whilst you can.

 

[Hugh Jaleak]

Running off the hot water is one way of draining the CWSC, but also costs you all your hot water in the process! If there is any cold outlets from the CWSC (e.g. mixer shower) then whilst it may take longer, it'll retain the cylinder contents and save energy having to reheat the water when you have finished.

As said, whilst the system is drained, it would be wise to replace the GV, either with another or a lever type valve which may have a longer lifespan.