need to work on on water pipe, can i without draining the hot water cyclinder

stolt

hi i've got to plum in a new sink in our utility room, the cold is fine i no where the stop !!!! is but i also have to sort out the hot tape for the sink (theres a pipe which has a stop end on it) but i dont want to drain the hot water cyclinder if i can help it) tried googling it, and kind of confused myself, can i just turn the mains cold stopcock into the house and then the the big cold water storage tank off in the loft and then there will be no pressure for the hot water to come out.


thanks

crazyguy

Is there not a seperate feed running off of your hot water tank that you can just turn off ?

ariba10

A hot water cylinder works on an overflow system. (The input is on the bottom of the cylinder and the hot water overflows out through the top)

If you stop the water going in, none will come out.

stolt

ok thats how i understood it, so i have to either turn the mains stopcock off and then just as precaution either find a cold water stopvalve feeding the hot water tank or tie up the ball in the cold water tank.

ariba10

Tying up the ball valve is the way that I would do it.

The valves that are usually put in these systems are gate valves and not very efficient.

stolt

ariba10 wrote: »

Tying up the ball valve is the way that I would do it.

The valves that are usually put in these systems are gate valves and not very efficient.

yeah good point, i remember a plumbing saying that too me once, something along the lines that the gate valves just spin round.

cheers

stolt

andrew-b wrote: »

There should be a stopvalve somewhere between the cold water tank in the loft and the hot water cylinder. Either it'll be near the cylinder or in the loft. If you merely turn off the cold feed to the cold tank you've still got probably 50 gallons of water heading for the hot cylinder that you would have to drain down.

You'll still have some water in the pipework so have bucket or two and old towels to hand. If your unlucky the stopvalve might let-by - ours did so i got quite wet rather than drain the whole lot down!

Add an isolator valve onto the pipework for future use.

cheers andrew, do you remember me mentioned when i took the old sink out and was face by boiling hot water coming out and me running around like a nutter not sure what i'm doing..... lol

mikey72

andrew-b wrote: »

There should be a stopvalve somewhere between the cold water tank in the loft and the hot water cylinder. Either it'll be near the cylinder or in the loft. If you merely turn off the cold feed to the cold tank you've still got probably 50 gallons of water heading for the hot cylinder that you would have to drain down (Edit. by running the hot taps).

You'll still have some water in the pipework so have bucket or two and old towels to hand. If your unlucky the stopvalve might let-by - ours did so i got quite wet rather than drain the whole lot down!

Add an isolator valve onto the pipework for future use.

Or just be seized solid and refuse to turn.
I usually stuff a cork/cloth/stopper into the outlet pipe of the header tank, than wrap a towel around the pipe to the hot tap, get an insolating valve ready, cut the pipe, and get the valve on.
Don't drop the valve.
And it's a real pain if the customer has left the immersion on.