Hot water coming from cold pipe

Old 06-25-12, 06:12 AM
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Hot water coming from cold pipe

This is in a 2 family home - up and down. When you turn on the cold water, it turns hot for a while and then goes cold and stays cold. If you feel the cold water inlet pipe to the tank, (upstairs tank) it's very hot and if the water hasn't run, it extends up to the main cold water pipe, which is why the water comes out hot for a while. Something is pushing the hot water up the cold inlet pipe. I installed new hot water tanks because I was told that the inlet pipe in the tank had to be broken, but it didn't change anything. Any suggestions? Ken
Old 06-25-12, 06:26 AM
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Most tanks have a little rubber flapper check valve on the inlet to help prevent the back flow of water. Maybe it was removed or damaged when the new tank was installed. The stickler is if it was also happening with the previous tank as well.
Old 06-25-12, 06:54 AM
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Its thermal expansion.

Do you know what the pressure of the incoming water is?

Did you install expansion tanks at the water heaters?

mike nj

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