I just had my gas water heater replaced. Ever since the replacement, when I turn on the cold tap on any faucet in my house, it runs cold for about 15 seconds, then hot water starts coming out. The hot water keeps getting hotter and runs for about 30 seconds, then cools off and goes back to cold. This happens on every faucet in my house and has been happening for the past two weeks since the new water heater was installed. I called the plumbing company that installed it and they are stumped. I cannot live like this, my daughter has almost scaulded herself several times. Can you please help?