Turning off water supply?

Question

hi im a little bit impaired when it comes to plumbing- I need a bit of help here- I want to change the washer in a tap- so i turned off the water mains outside- then opened up all the cold taps to drain them- but now boiling hot water is coming out the cold tap??? do I also have to shut off the geyser

Answer 1

Open the hot water supply and let the pressure out.

Answer 2

The hot water water is finding a path through a faulty valve (tap) washer to the cold water side. Since you shut off the main water supply, it can only be the pressure from your hot water tank. Open the drain at the bottom of your hot water tank to relieve the pressure from there.