Turned of water at mains - but hot water still run

defluxing, Jan 3, 12:08am
Afternoon I have turned the mains tap off at the gate, and cold water has stopped flowing, but the hot water is still feeding through. I’ve filled two buckets worth and it ain’t showing any signs of slowing. Ive never encountered this before, to me when the mains is off, neither hot nor cold should flow. What trick am I missing?
The cylinder is a 1969 low pressure (yes, very much in need of replacement!) that is wetback (although wood burner it is/was connected to doesn’t work) so not sure if this is why there is an extra step I’m not aware of?
There is a tap running off a pipe which appears to go into the roof (I assume to the header tank?) at the very top of the cylinder but it won’t budge left or right, so not sure if this should move, and would be my solution? Suggestions gratefully received.
gabbysnana, Jan 3, 12:46am
Cripes turn off the cold water in tap at the bottom of the cylinder, before you empty your tank. Turn all taps on so you don't get an airlock. Turn element off so you don't burn it out.
stevo2, Jan 3, 12:53am
hot water will run until header tank is empty. Look for a tap between it and the cylinder.
defluxing, Jan 3, 12:55am
I’ve turned the element off already, did that before turning the water mains off, and there is not a tap under the HWC. I’ve also run the hot water for 4mins solid - which I would have thought should have drained whatever is in the header tank.
defluxing, Jan 3, 12:57am
There is one, but it is not moving at all. so essentially will the header keep filling with what’s in the main HWC if I cannot turn that tap?
nzmax, Jan 3, 1:05am
As long as water is getting into the cylinder from the header tank, you will have water at the tap. The header tank will become empty at some point. My last house didnt have a tap between the header tank and cylinder so couldnt be stopped that way. Now its time to get your arm wet (hopefully your tank isnt too deep) and block the outlet with something that isnt too difficult to remove. cork, wine bottle stopper, gladwrap rolled into a ball, rag, or anything else you have lying round. You will still get some water out of the hot tap until the outlet pipe from the tank is empty.
defluxing, Jan 3, 1:51am
Righto - will give that a crack! Thanks.
bethd754, Jan 3, 5:00am
My hot and cold water tap just been replaced yesterday and the plumber turn off the main water then asked me where was the hot water cylinder so he can turn it off before replacing the taps.
lythande1, Jan 4, 12:21am
Cylinder isn't empty. Turn the tap off by cylinder.
bryshaw, Aug 29, 10:04am
The hot cylinder gate valve can be very hard to budge if not turned for a while. My plumber curses when he has to cut the water off.