Intermitted Leak

Have you ever seen this


Had a call about a leak on the my NEWLY remodled unit. I went there and it look like the tp valve let out water like it was suppose to and tenants had the temperture way tooo high!! I turned it down and said call if any other issues. Did not see any leak going on while i was there.


Well 2 days later this time its alot worse, carpet satuarated with water. I check the water heater again, just see water , no leak,hmm maybe the bottom is leaking. Look at the bottom its rusted pretty good so its POSSIBLE but still didnt see a leak happen while im there. I even check the pipes and everything. I buy new heater just to be sure (everything else is new anyway). Well while i install the water heater, I test it and turn on faucets/main water too. still no leaks.


Turn off faucet and start cleaning, then WAALLA!! a leak starts. I see from The ceiling theres water going. I go upstairs, no leaks,or anything on!!I scratch my head , go back down and start tracing that leak.


Well i found it, I could KICK myself. the old copper flex to the water heater had a pin hole 'pressure' leak. the spray too light to almost see.


I call it a PRESSURE leak because it ONLY leak when there was enuff pressure. See when the tenant would use the shower/sink hot water, it would NOT leak. So when the faucet is off the water tank heats and builds pressueR and then at night when everyone is sleeping, it leaks and when they get up and use the bathroom it STOPS!!


Ever see anything like this?? How would one ordinary find this type of leak??Im still amazed at how some plumbing works

There is a similar problem that occurs when you have a closed system. Your system is "closed" when you have a pressure regulator valve in the supply line. Some newer water meters have a check valve which create the same symptoms. Basically what happens is when water is heated it expands. In an open system, this expansion is just absorbed by the city water main and causes you no problems. However, in a closed system, the PRV or meter check valve prevent the expansion from escaping into the main and the pressure in your water heater will rise rapidly and to 150 psi and the TP valve will trip. In a closed system, you need to install an expansion tank which handles the expanded water. It sounds to me like your copper flex line was bent too much and created a crimp and the pinhole leak. The cure for that is to get a new flex line. You do not need an expansion tank unless you have a PRV or the newer style meter. These meters are installed to prevent the possibility of contaminated water from getting into the city water main.

We recently had a thread on this. The conclusion was that the flex copper products are not all the same quality. Probably best to change it out anyway when you replace a HW tank.

As for a "trick" in finding a small leak like that. No trick. You just use your eyes and perhaps a flashlight and keep searching 'til you find it. You're lucky you didn't have to open up the ceiling or a wall to find it.

Gary Swart said:

You do not need an expansion tank unless you have a PRV or the newer style meter. These meters are installed to prevent the possibility of contaminated water from getting into the city water main.

Click to expand...

What is PRV??