Cold/Hot water crossover problems

[JoeWras]

Well I learned something today that I never realized existed: cold <-> hot water crossover due to defective faucets. It is a "silent killer" of steady, tempered water for your shower or sink.

Anyone ever have this problem, know about, and fix it?

Symptoms: cold water in hot, hot water in cold, showers that fluctuate wildly, showers that only get lukewarm.

Did you know that your single handle sink can cause this? Silently, without any indications that it is letting your warm and cold water cross-over without your knowledge?

I didn't, until today.

I'm helping our facilities guy at a non-profit facility that has a kind of motel layout. We have all kinds of problems with the water temperatures. Turns out that well-used single handle faucets have internally worn and now are allowing mixing, while just sitting there doing apparently nothing.

It's a real problem, especially when you have 38 mixing faucets to test.

 

[HawkeyeNFO]

It's a real problem, especially when you have 38 mixing faucets to test.

Ain't scared.

 

[sengsational]

At first I thought "A stethoscope is your friend" but it probably crosses over only when certain fixtures are running (pressure differentials).

 

[old medic]

We have a similar issue with camper showers. If you hit the showerhead botton to cut off to save water. The hot water being slightly higher pressure due to expansion from heating, will push into the cold water line.... then when you open the showerhead... it gets real hot for a few. You can put a check valve on the cold side to prevent it.

 

[JoeWras]

At first I thought "A stethoscope is your friend" but it probably crosses over only when certain fixtures are running (pressure differentials).

Actually, using some sort of listening device is one of the ways to diagnose this. You are spot on!

After I dumped a thread, I did more research. Basically, it involves turning off the cold water feed to the water heater. Then turning on the taps to hot. If water comes out, you have a cross-over.

To figure it out, both listening and touch can be employed. Listening works a lot of times because the water is scooting through a worn groove or something in the cartridge and makes some noise. Touch of the pipes below can detect a hot to cold fast change.

For showers, it is a challenge. The only method I found is called the "Eatherton Method". This guy has 15 minutes of fame, you can look him up. Here you can take off the shower valve escutcheon and then feel the pipes for cross-over.

All of this is time consuming.

For most people who dare to wander to this thread, "old medic's" issue is very actionable. If you have a shower valve that allows a turn off at the sprayer and you decide to leave the valve open, be prepared for all kinds of problems with your sink. You may even get hot water to your toilet. Don't do this. Always turn off the valve, not the shower head.

As for me, someone who is helping with a commercial building... well, it is just time. I am retired, I am a volunteer. I will, however, beat up the CEO and facilities director to never buy a single handle faucet again. Two handles fixes the problem.