TX Hot water in tank, cold water in taps

[TXIslander]

Are you sure the water leak alarm valve is open? You should be feeling hot coming out the pipe on the top of the water heater, even if there is a crossover somewhere else in the house. The symptom of a crossover is usually lukewarm water. The hot pipe at the top of the heater gets fully hot, it just gets diluted down to lukewarm somewhere downstream. The fact that you're not feeling any heat in that pipe at all makes me wonder if the alarm valve is closed.

If there was a pre-existing crossover, it might have gone unnoticed for a long time. Now the water alarm valve was triggered somehow by the power outage & is stuck closed. The pre-existing crossover is still there, and this allows some cold water to go into the hot pipes. Now when you draw water off the drain valve at the bottom of the water heater, there is reverse flow into the water tank, from the cold pipes in the house, into "hot" pipes, via the pre-existing crossover, then finally into the tank. Maybe? It's hard to diagnose this kind of stuff without being there.

Hot damn! The award goes to PHOG! I pushed the power button on the leak alarm and immediately the WH went “glug, glug, whoosh, pop, hiss...” I yelled down to my family to open a hot water faucet and right away the pipe out of the machine got hot. I haven’t tried every faucet yet but, but there’s hot water coming out of the first one we tried. I’m sure there’s still a crossover issue, which we’ll address, but the more immediate issue seems to be fixed. Thank you!!

PS The alarm was installed by the plumbers who replaced our WH a couple of years ago and we thought it just beeped like a smoke detector. Turns out it’s Z-wave technology that allows us to control the whole machine with an app and can obviously shut things down when it thinks there’s a problem. We learned a lot today.

 

[Phog]

Glad you got it fixed, isn't it amazing how much of an inconvenience not having hot water is? You don't realize how important until you don't have it.

The most common source of crossover is usually the pressure-balancing single handle shower valves. There is a cartridge inside with a rubber diaphragm that wiggles back and forth to balance the hot/cold mixing according to pressure. It wears out eventually and then gets a tear, which allows water to go across. You can usually buy the cartridges for most common brands and models of shower valves in-stock at your local plumbing store. Many come in a kit that comes with everything you need (and sometimes even includes a little packet of silicone grease).

Not definitely a shower valve, but definitely the first place I'd look.

Honestly though if you're not having problems with lukewarm water unexpectedly coming out of random fixtures, it could wait until a different & more convenient season for your attention.

 

[Sponsor]

 

[WorthFlorida]

I was under the same impression that the leak detector was nothing more than an alarm.

Here is a recent post where the shower cartridge replacement fixed his crossover problem. It was the the same suggestion to close all stop valves. What made it some difficult was he had a recirculating system and had hot water coming out the cold side.
https://terrylove.com/forums/index....-coming-out-the-cold-inlet.92285/#post-667109

 

[Phog]

Crossover can lead to all kinds of funny things. Like toilets filling up with hot water from the crossover

 

[Reach4]

Finding that there is a crossover could be a beneficial side effect of the leak detection failure.

Crossover can lead to all in kinds of funny things. Like toilets filling up with hot water from the crossover

Crossover in progress can be detected by checking the temperature of the pipes. If no flow for a long time, the pipe temperatures should be room temperature. An IR thermometer can be useful, but so can the fingers.

 

[Phog]

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