Cold Faucet On = Water out of Hot Pipe

[MasterPlumbersKeymaster]

I have removed the existing hot water heater. With the cold pipe reconnected, and the hot out pipe still disconnected, I used the cold water in the house temporarily. Every time I turned the cold water faucet on, water came flowing out of the disconnected hot water pipe. If I disconnected the hot water pipe from the hot water heater, why does water come out of it only when I turn the cold water on in the sink? If cold water is somehow connected to the hot water line somewhere else in the house, how do I find it?

[nicktheplumberParticipant]

I guess that some of your fixtures (sinks/showers/bathtubs) have “mixer” valves or “diverter” valves, and when you open the cold water side water is diverted back into the hot water supply lines…

NtP

[Author]

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