Water pressure and volume problems

[Gurrenteed]

Here's the background:

My 4 bedroom house was built in 1994. There is a 3/4" copper supply line that comes through the foundation and later splits into pex for the rest of the house.

I recently was looking at installing a sprinkler system and found that the static pressure coming into my house is 130 psi! I initially didn't believe the gauge and thought it must be faulty, so I took the gauge to work (I'm a firefighter) and tested the pressure readings on a fire truck outlet and the pressures matched. The pressure gauge is good.

If I crack open any faucet in the house while the gauge is in place, the residual pressure drops to less than 60 PSI. If I fully open the faucet, the residual pressure drops below 30 PSI.

PRV - the pressure reducing valve is a 3/4 Zurn Wilkins #70. I found the adjustment to be all the way in, which I believe provides the highest pressure. Adjusting this valve did nothing to the static pressure but it significantly reduced volume to almost nothing.

I know I need to either replace or rebuild the PRV. Could this valve also be causing my volume problems? Thanks.

 

[Reach4]

You could have a blockage after the PRV. Do you have a whole-house filter? Have you checked that there is not a partially closed valve before or after the PRV, but after the pressure gauge?

http://www.zurn.com/media-library/web_documents/pdfs/installation/is70xl-pdf says there is a cartridge. Often the low lead and older units can use the same replacement parts. Check on that.

Some PRVs have a screen, but yours does not seem to be one of them.

Edit:
Oooh... http://www.homedepot.com/p/Zurn-Wil...er-Pressure-Reducing-Valve-RK1-70XL/203374788 shows a screen for the 1-inch repair kit. I presume other sizes would be the same in that regard. Perhaps you could just clean your screen.

http://www.zurn.com/products/water-control/pressure-reducing-valves/rk1-70xl says this kit is good for the Zurn 70.

 

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[Jadnashua]

A malfunctioning PRV can affect both the outlet pressure and the volume.

Do you also have an expansion tank in your system? If not, thermal expansion can temporarily increase water pressure high enough to open the safety T&P valve on your water heater unless there's a leak somewhere in the house (water doesn't really compress, so any increase in volume spikes the pressure unless it can go somewhere like into an expansion tank).

 

[Gurrenteed]

Yep. I do have an expansion tank.

I went ahead and pulled my PRV apart to check the screen. It was very corroded on the inside. The diaphragm bolt just spins. Yes, I was holding the diaphragm disc and the bolt was still just spinning and wouldn't come out.

I went ahead and cut the old PRV out and replaced it with a new one. All problems are solved. Volume is great and pressure is right at 75 PSI.

Thank you guys very much for your responses!