About 2 weeks ago our hot water started getting less and less hot, now it is completely cold. If I turn the cold angle stop off at the sink, so only the hot water line can feed the faucet, and turn it on, water flows. If I turn it to the completely hot setting water flows, but if I turn it to the completely cold setting the water stops. (No crossover in the faucet). Here is the tricky part, if I turn off the cold water feed to the hot water heater, with the faucet on hot only, the water will still run. This happens in all of my sinks except one. In the hookup closest to the hot water heater, if I hook the hose to the hot water angle valve and turn it on, HOT water flows out. If I then turn off the supply to the hot water heater, the flow stops (as it should). Only this one sink functions this way. When this is happening I can hear the water being taken out of the hot water heater, and new water being put in. When I turn on any other faucet it is not even trying to draw water out of the hot water heater, even if I have the cold angle valve on the faucet turned off (so it can only draw from the hot circuit). Also, I turned off the angle valves to the dishwasher and washer/dryer for all the tests.

To summarize, the faucet closest to the hot water heater works flawlessly. All other faucets will only run cold. When the cold water angle valve is turned off, and the faucet is turned onto hot, water runs, but is cold, and is not even trying to draw from the hot water heater. Everything seemed to work fine 2 weeks ago, and no plumbing has been tampered with.


Thanks Will

  • 1
    I'm trying to visualize your circuits as described, but a graphic would be very helpful in diagnosing your problem. – bigbull15 Apr 25 '16 at 3:43
  • Perhaps there's an intermediate cutoff and mixer valve in the hot line feeding all your "other" sinks and someone accidentally closed it. This would be a weird arrangement but would explain why you still get water (cold) from the sinks' hot taps even when the heater is shut off. – Carl Witthoft Apr 25 '16 at 12:48
  • The cold water enters the house right above the hot water heater, it then tees to the hot water heater (with the shutoff valve in line) then continues down under the floor. The hot water goes up from the hot water heater into the space between the 1st floor and the basement. – William Maroon Apr 25 '16 at 15:29
  • There has to be a mixing valve of some sort somewhere, I turned off all the faucets at the angle valves and replaced all the cartridges in the showers. The cross-over isn't happening at those points. And the cold water is full strength when coming out of the hot side of the sink, so it has to be a pretty sizable connection feeding it. No one touched any of the plumbing. Is there something that could have corroded/failed allowing the water to mix? – William Maroon Apr 25 '16 at 15:31

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