Shutting off the Hot Water

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Old 11-30-20, 01:57 PM
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Shutting off the Hot Water

I have 2 water heaters. I have shut off valves installed on the hot and cold side of each water heater. I turn on my double handle faucets hot only and I am getting hot water. Keeping the faucets on, I turn off the hot water valves at the water heater. Now I am getting cold water from the hot side of the faucets. Shouldn't the faucets turn off? I suspect there is a crossover somewhere, but I don't have an idea on how to trace it. any suggestions on how to trace the lines?
 
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Old 11-30-20, 03:03 PM
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Hot to cold crossover.

Bathtub or shower or sink with a "mute" control at the spout or shower head used to turn off the water but the wall or tub faucets are still turned on.

Washing machine hookup still open and there is a defect in the machine mixing valve allowing crossover.

Anti scald device (sold separately) consisting of a hot-cold crossover, under a plumbing fixture or above a water heater.
 
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Old 12-01-20, 01:43 PM
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I appreciate the response. Can you elaborate what the "mute" control is? I've never heard of it. I realize that I asked multiple questions in my initial posting. I also noticed many views to the thread as well. So the first question of; turning off the hot water line, should turn off all hot water correct?

@moderator should this be moved to water heater section?
 
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Old 12-01-20, 03:10 PM
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I would have expected that turning off the hot water outlets from the water heaters, all flow from the hot water faucets should have stopped.

Other causes:

A recirculation loop whose purpose is to bring hot water to faucets without waste and so you don't have to wait when you first turn the hot faucet on.

I was going to mention an expansion tank releasing its contents but you said you opened the upstairs faucets first and by the time you ran downstairs to turn off the water heater outlets and got back, the expansion tank would have finished doing that and you would not see any more water coming out. Also the expansion tank should be on the cold side going into the heater so it would not cause cold water to come out a hot faucet.

I used the word "mute" for a water shutoff that did not change the hot-cold or low-high settings of the faucets. Something like the sound mute button on a TV remote control.
 
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Old 12-02-20, 10:00 AM
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Hi Ė

Not an expert but as has already been pointed out: You have a faulty valve somewhere in the house which is allowing a flow from the cold pipe over to the hot pipe. I think it could be anywhere. One method to find it is :

(1) Turn off the valves to the washing machine to eliminate a faulty valve there.

(2) turn on the water at the hot faucet where you are observing the problem (i.e., cold coming out of hot even though hot water from water heater shut off) and just let the water run.

(3) Any place in the house where you have a single action faucet check the hot and cold pipes going to that faucet. If both pipes are cold that faucet would be the problem.

I havenít had this problem or done this myself, but I think if any of the locations with a single handle faucet or wherever the cross-over might exist, also has a hot water shutoff valve, then I think if you closed that hot water shutoff valve that would stop any crossover and the water flow from the hot pipe would stop.

(Take a look at the plumbing around the 2 water heaters, I canít exactly picture how but make sure that with certain valves open and others closed you are not sending cold water into the hot water pipes.)
 
 

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