After shutting off the water for several hours to install new sink and toilet now I have warm,almost hot water coming out of every faucet from the cold tap. It takes a full minute for it to get cold.

My plumber is stumped.

Can you help?

  • 1
    Hello, and welcome to Stack Exchange. Almost certainly the problem is the sink bridging the hot and cold lines. Test the temperature of the supply lines to the sink, and see if the cold side seems hot. – Daniel Griscom Dec 20 '18 at 3:40
  • One other posssiblity.... a mixing valve that someone touched. A plumber shouldnt be stumped by this issue. – noybman Dec 20 '18 at 3:55
  • Ohhh, one more possibility, The tank is on, cooking away, but the outlet is blocked, so as pressure builds, (even though it is moderate), it is forcing its way backwards, into the cold feed. – noybman Dec 20 '18 at 5:46

I'm inclined to side with nobyman's shower mixing valve failure. A typical issue resulting from the water being turned back on all at once or too quickly and rupturing the rubber and plastic parts of this century's shower valves.

This is most common with ball valves. The best practice, especially with ball valves, is to just crack them to open and wait for the system to fill and return to silent before opening the valve the rest of the way.

Very rare but also happens with basement shut-offs that are quite a distance from the fixtures by creating a water hammer. This is one reason to have individual shut-offs for each and every fixture everywhere.

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