Expansion Tank?

Hello,

Do I need an expansion tank? Here is the series of events that leads me to ask this question:

1. Back yard sodded
2. New irrigation meter installed by city
3. City adds irrigation meter and replaces old house meter, both include backflow device
4. T&P valve starts to leak
5. T&P valve replaced
6. T&P valve still leaking
7. Plumbers called and discover pressure of 140 PSI
8. Water line replaced (galvanized->PVC), regulator added and set to 78 PSI
9. T&P valve still leaks

It seems like the only thing I am missing is an expansion tank. Is my thinking correct? If an expansion tank does not stop the PRV leak what do I look at next?

Thanks...

tank

Proabably, but if it doesn't fix it find a better plumber who can diagnose the system and find the cause of the high pressure.

PRV = Pressure Reducing Valve

Is this what is leaking? This is the same as the regulator you mentioned.

Cass said:

PRV = Pressure Reducing Valve

Is this what is leaking? This is the same as the regulator you mentioned.

Click to expand...

I meant T&P. The T&P is still leaking.

I would not call those plumbers who installed the PRV back. You now have a "closed system". This occurred when the new meter with the backflow prevention was install, and even if the meter didn't have the backflow prevention, the PRV has one. When your water is heated, it expands. Without any backflow prevention, you do not have a closed system and the expansion is absorbed by the city water main. Once the system is closed, you must provide an expansion tank. Whomever installed the new meter should have told you that and the plumbers who install the PRV should have told you that.

With out a doubt it needs an exp tank and they should have known that when they did the job.

The backflow preventer was the original source of the problem. The plumber did not serve you well when he added a PRV that probably wasn't needed.

He probably figured he would get a second call and more money if he did the PRV first and then you had to call him back.

Get an expansion tank, the kind made for potable water, not for boilers. Connect it anywhere in the cold water line after the PRV. Most people like it somewhere on the input side of the water heater.

Bob NH said:

The backflow preventer was the original source of the problem. The plumber did not serve you well when he added a PRV that probably wasn't needed.

He probably figured he would get a second call and more money if he did the PRV first and then you had to call him back.

Get an expansion tank, the kind made for potable water, not for boilers. Connect it anywhere in the cold water line after the PRV. Most people like it somewhere on the input side of the water heater.

Click to expand...

My pressure was measured at 140 PSI, I thought I needed the PRV valve.

Thanks...

errodr said:

My pressure was measured at 140 PSI, I thought I needed the PRV valve.

Thanks...

Click to expand...

You did. Everything that requires water to operate as a plumbing fixture is engineered for 60psi. You take it beyond that and premature wear and a slew of other problems will crop up.

When I install PRV's I will not install it without a EXP tank, period. I tell them they go together like peanut butter and jelly and if I was to install the PRV without the tank......I can actually recreate the high water pressure they once had........until someone flushes a toilet or runs a sink.

Get rid of the plumbers as it seems they are uneducated on simple issues regarding thermal expansion in closed systems.

Make sure the expansion tank is set to the working static pressure you set the PRV BEFORE INSTALLING. Setting that PRV at 78 is 2 pounds from enforcement of putting the device on the line.

Back it down to 60.....it will operate everything in the house with no problems. The rest is waste, literally.