Hot water mixing in with cold?

[sportykev]

Hello,

First time member, first post, hoping for a helping hand.

We just started experiencing the sound of water running behind the shower on the top floor. There is no indication of a leak. But I have a theory (without fully understanding how the hot/cold valves work), but please hear me out. This noise stops if I shut the hot water line coming from the hot water heater.

We have a Moen single handle shower faucet. I was thinking to 'bleed' the hot water lines by shutting off the cold water intake into the hot water heater while leaving the hot water line open. I then opened all the faucets in the house to hot to allow for the pressure to be released, and have all the hot water go back to the basement exiting the slop sink.

There is one problem, the shower (top floor) where we hear water constantly flowing, has a constant trickle of water coming out, and it's cold. No hot water exiting. Does this indicate that the hot water is 'mixing' with the cold water causing a constant running of the hot water? This would solve a couple of things for us. Our water bill has increased almost double, and we've been noticing that our hot water heater is turning on more often than it should.

Is this mixing normal? Is it a setting? Is it a bad valve / cartridge? I only know about the Posi-Temp pressure balanced shower cartridge from all the YouTube I've been watching lately.

TIA!!

Kevin

 

[RS]

If your water bill has doubled, where is the water going? If it's going down the sewer that's one thing, if it's inside the wall you should notice it, and it could do serious structural damage. If it's only a bad faucet cartridge it should just be circulating and not be wasting water, you need to get this fixed. Until you do, shut the water off when you don't need it.

 

[sportykev]

I would add that we have an under-the-sink RO unit that is one route of 'escape'. Our en suite shower, which is also a 1-handle Moen, and during the test in my initial post, no water was coming out, rather air could be heard sucking (the vacuum created) with the hot water retreating back. Is the 'mixing' a behavior of a bad cartridge?

 

[Jeff Handy]

Mixing hot and cold water is commonly called crossover, it can definitely happen inside a defective single handle valve cartridge.

And the symptoms can appear at other fixtures downstream of the bad cartridge.

But that would not lead to any extra water usage.

 

[sportykev]

Mixing hot and cold water is commonly called crossover, it can definitely happen inside a defective single handle valve cartridge.

And the symptoms can appear at other fixtures downstream of the bad cartridge.

But that would not lead to any extra water usage.

Thanks Jeff. Would the sound of water flowing when faucet is off be a symptom of a bad cartridge at least?

 

[Jeff Handy]

Yes, there can definitely be a sound from water flowing through the cartridge between hot and cold, even with the faucet or valve turned off.
But if your water bill is truly way up, then you also should start investigating for a leak somewhere.
Or look for problems like furnace humidifier stuck on, or set too high.
Water softener running too often or control valve damaged.
Water heater frequently discharging water out of the relief valve and not being noticed.
Toilets running constantly, from bad fill valve or bad flush valve.
Broken hose spigot leaking water outside.

 

[sportykev]

I got around to replacing the Moen cartridge, the shower head is less drippy but the sound of water flowing is still... flowing. I can't tell if the sound is from the mixing valve or somewhere below, the sound resonates everywhere but it's most loudest at the mixing valve. There are no indications of leaks that I can tell.

As far as mixing valves are concerned, are those adjustments on the sides of this for dialing in the balance between Hot and Cold?

I'm in denial that there is a leaky pipe since that would ultimately lead to breaking of walls.

 

[Jeff Handy]

Those slotted stems operate the service stops, built in shutoff valves for the incoming hot and cold water.
Very handy, because you can turn them off to service the cartridge, and leave water on everywhere else in the house.
Or in a condo or apartment, no need to contact maintenance to turn off the water to your whole floor or wing.
They are usually set to fully open.
If they are not operated for many years, they might freeze up and not rotate.
Not all valves have them, because they are optional and they cost extra.

 

[Twowaxhack]

Sounds like you have a leak that you can’t find. I suggest calling a professional.

 

[TomFOhio]

Is your house on a slab, crawl space or basement. I agree, you have a leak somewhere on a hot water line. Could
be underground

 

[sportykev]

Hello, just following up, hate to leave threads hanging. Worse case was realized. I eventually found the leak after hearing sounds for weeks. A puddle started to develop from behind the walls towards the bottom in the garage, I cut a bunch of drywall and could not find any pipes so it was determined that our hot water line was indeed running through the slab, and a leak was on the hot water line rising up.

I hired plumbers to circumvent the copper pipes in the slab, and they rerouted using PEX. Leak is obviously gone but it took too long to diagnose as there was no visible leaks for such a long time. Anyway, case closed, thank you all for listening.