I'm replacing a toilet ballcock for the 3rd time. Never occurred to me what was causing them to fail...

1st one, when we moved in some 15 yrs ago.

2nd one, when the city switched us to the "new" main, some 5 years ago. Meanwhile, I had replaced ALL the plumbing in the house (minus a PRV - none there). House was supplied with a 3/4 galvanized main.

Now, back to the ballcock. It failed, and in a big way. The water would NOT stop. AND, the shutoff failed; thankfully the overflow tube could handle it while I rummaged through the garage (doesn't everyone keep a spare?). I'm thinking the new main and the new plumbing probably let loose some of the HARD water sediment that attracts all of the Urologists to our area and lodged in the seat of the shutoff valve. (BTW, I put in one of those 1/4 turn balls.)

Having done all that, I started thinking. Then I went back to BigBox and got a pressure gauge. 120 PSI at the main shutoff inside the house!! Seems WAY too high to me.

Going back to BigBox - PRV.

What I'm now worried about is the new PRV failing because of such a high head pressure. Should I put 2 in series to knock the pressure down in stages? What say the experts on this?

Regards,
Stew

Hi Stew,
[QUOTE][/I went back to BigBox and got a pressure gauge. 120 PSI at the main shutoff inside the house!! Seems WAY too high to meQUOTE]
Me Too! Smart move to check your pressure. The average house pressure runs somewhere between 45 and 60 PSI. You have twice that much. A single PRV should do the trick. You shouldn't have to stack them in series. Good luck, Tom

OK, now I'm digging deeper - missed one GREAT post on high water pressure. Reading that, I'm seeing that if I install the PRV, AND it has a check valve. I'm going to need an expansion tank to avoid my Hot Water heater from popping it's PRV. True?

Should I install an expansion tank while I'm at it, just to avoid the inevitable headache?

Yes, you will need to install the expansion tank, to avoid pressure relief valve from leaking or popping off. And yes, as Tom said, one prv is all you need. Just check the pressure periodically. If you are adding a prv, just as well add an inline pressure gauge while your at it. This way you will be able to keep an eye on pressure constantly.. And yes, 120 psi is way, way, way to high. My code states that if the incoming pressure is over 80lbs you have to have a prv. That said, I agree with Tom that normal pressures should be between 45 and 60. I tend to lean closer to 60. Lee.

Stew,

I agree with Tom and Lee, the pressure should be set 45-60 psi, and also I have the link attached for info regarding the expansion tank, Thanks.

John

Learn About - What is thermal expansion, selecting an expansion tank, Potable vs. Non-Potable systems. (http://www.watts.com/pro/divisions/watersafety_flowcontrol/learnabout/learnabout_thermexpansion.asp)

Speedball - still can't add more reputation to you - Cheers! Very helpful as always.

OK. PRV - check, Gauge - check, Expansion tank - check. Appreciate the help. Hope to return the favor. Regards.