I need to change my tap in the kitchen and obviously need to shut off the hot and cold supplies. Handily there isn't any isolating switches on either! To save me having to drain the whole hot water system does anybody know of a product which can clamp around the hot water feed and then turn into an isolating switch?
Are you gravity fed hot water? If so isolate the cylinder by the gate valve in the airing cupboard where the cold feed enters the cylinder at the bottom. This will stop cold water entering from the loft tank and ppushing hot water out the cylinder.
The cylinder is still full but the water cant get out.... open the hot tap and the flow should stop in less than 30 seconds.
if you have a combi then turning the mains off will do the job
if you have a vented system then turning off the cold feed to the hot water cylinder will the job
if there is no gate valve on the cold feed to the hot cylinder,thats the pipe coming from the cold water tank and entering the bottom of the cylinder see if its located by the cold water tank
Hi Nitro, thanks for your feedback. I believe that I do have a gravity fed system as I have a tank in the airing cupboard and also a cold tank in the loft.
I would say that I'm quite a competent diy-er, but just to be sure how can I make sure that I'm turning off the cold feed to the cylinder as there's about 4 different taps and none of them are an obvious cold feed source.
I guess I could try each one and see when the hot water goes off, but I'm a bit paranoid that I could be messing with things I don't know what they do and seeing that it's winter time the good lady indoors might not be too chuffed with a plumbers call out charge!!!
The hot water shut off is normally on the pipe run somewhere that is labelled '2' in that picture above. It might be higher up that pipe though, but still on that pipe somewhere (maybe even ceiling height or even in the loft as Bob said). Also remember that your cylinder might be in a different orientation than that of the picture i.e. pipe '2' might appear on the left in your house and not right as pictured and 3 and 4 might be on the right (3 and 4 are return and feed from the central heating respectively that heat the water)
So if you shut off pipe number 2, you stop cold water from the loft tank entering the cylinder at the bottom. Normally when you open a hot tap hot water leaves the cylinder by number 7 as cold from the loft (via pipe 2) pushes the hot out of 7 via the height (and thus pressure) of the loft tank water pushing down. If you isolate pipe 2, this cannot happen. The cylinder is still full of hot water but it cant go anywhere as it cant be pushed out via the 'head' of water from the loft tank. So if you now turn the hot tap on, you will get a trickle for say 30 secs whilst the water already in the pipes empties - it will then stop.
If your still in doubt, post a picture and Il tell you which to shut off.
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