Water Pressure Low - But Builds Up

[Chris]

All,

I own a condo that was built in the mid to late 70's. Recently, we had individual water meters installed at each unit, and a plumbing company installed PRV's at each unit as well. Started noticing some strange things after this happened. First - the water pressure was cut in half...which is not all that bad, being that our pressure was around 105 pounds prior. Over the past few weeks, I have noticed that our pressure seems to build. For example, after some time not using the water, I can flip on the kitchen sink and the pressure is extremely high - then levels out.

The plumber came out again and replaced the PRV - still notice the problem!

Anyone have any suggestions as to what might be the problem here? I would also mention that our hot water heater is quite old (not sure how old...but during the inspection we were told that it probably had a couple of years left). Could this be a potential culprit?

Thanks

Chris

[Speedy Jim]

Anytime a PRV is installed, a thermal expansion tank is *required* on the water heater. The PRV prevents the high pressure created by expansion from returning to the street main. More:

If you get flack on this, call the city inspector to get their official position.

Jim

[Chris]

Interesting...

I have an electric water heater...does the expansion tank still apply?

Chris

[Anthony]

Chris wrote in news:Fi_Jd.19223$ky2.4539 @bignews4.bellsouth.net:

You are still heating water, water expands when heated. Pressure is a factor of volume in a given area. Since with all the water taps off, and the PRV in the line, you have a 'closed' area. Increasing the temperature of the water increases it's volume, the area is fixed, so the pressure goes up.