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oldave79 01-01-2016 07:22 PM

Checking Water Pressure
 
Good Evening,

I have an under counter water filter installed that is about 1.5 years old. I recently changed the filter cartridge, and found that the housing was cracked. To determine if this was a defective product or if I had a water pressure problem, I purchased a water pressure gauge from a home improvement store.

With all faucets turned off, pressure read 85. With a faucet running, it read 60.

I adjusted pressure reducing valve. Now with all faucets turned off, it still read 85. With a faucet on, though, it read 40, and the pressure coming out of the faucet was obviously reduced. That said, when I first turned on a faucet, the pressure would be higher, and then quickly drop off to the noticeably low pressure.

Does this indicate a faulty pressure reducing valve or a bad pressure gauge, or something else? I would like to set my pressure at 60.

Thanks for the input.

Ghostmaker 01-01-2016 07:25 PM

That would be a sign of bad PR valve. Make sure though that the outside faucet your testing at is not piped in the inlet side of the PR valve. It occasionally is done this way to allow higher pressures for a lawn sprinkler.

raylo32 01-01-2016 07:28 PM

Could possibly be a bad regulator. Only way to be sure is to check the pressure upstream of the regulator and compare to downstream. 85 sounds typical of city supplied pressure and if your regulator fails it can pass that through. I had this happen a couple years ago and had to rebuild my regulator.

oldave79 01-01-2016 08:03 PM

So even though adjusting the reducing valve caused the pressure to drop with a faucet running, it would still indicate that the PRV isn't working correctly?

PRV (and house) is only 2 years old. Do they normally fail that quickly? Guess I need to get a plumber out to check it.

Ghostmaker 01-01-2016 10:20 PM

Yes. The PR valve should reduce pressure when water is not running.

Because that is all it allows to enter the house.

jmon 01-01-2016 10:24 PM

Quote:

Originally Posted by oldave79 (Post 2846234)
PRV (and house) is only 2 years old. Do they normally fail that quickly? Guess I need to get a plumber out to check it.

Sometimes a piece of debris gets stuck in the incoming screen which may affect the way it works. This can be easily checked and cleaned.

Do you have an expansion tank on the water heater? If so, check and make sure it's set at the proper psi and not water logged.

If you can't get it figured out, your suggestion of getting a plumber to check it out is a good option. Hope you get it figured out soon. Happy New Year.

oldave79 01-01-2016 10:57 PM

Thanks! I will probably see if I can get someone out next week to look at it. I'm pretty handy, but my plumbing knowledge is more or less limited to changing fixtures and supply lines, though I suspect if I watch what the pro does to fix the situation, I may be able to rectify it myself should it reoccur in the future.

raylo32 01-02-2016 06:57 AM

I doubt the reg would fail in 2 years but I guess possible. Getting grit in it more likely.

As for the expansion tank.... if you have one and it is working properly the pressure rise after shutting a faucet may be slow and will depend on how fast the reg is leaking by, but will ultimately maximally compress the bubble and reach city pressure. IOW expansion tanks are really good for normal transients from water heaters and such but when a reg fails and leaks by you have an unlimited transient that even the biggest expansion tank can't cover.

BTW, replacing a reg isn't that difficult if you do decide to do it. The easiest way is to find the exact same reg unit and replace in kind. If it is difficult to remove the old one do what I did, just spin off the cap and swap the internals from the new to the old. 5 minutes and you don't even need to dust off your pipe wrenching, soldering, or gluing skills.

I also installed a permanent gage downstream of my reg in the port that the plumber used to set the reg initially so I can always look and see what my house side pressure is doing. I am not sure why they don't require them to be there since it is really hard to spot a bad reg without it. Without the gage you need to suspect you have a problem and get a gage to go look. Now I just glance at it whenever I am in my utility/laundry room.

Yodaman 01-02-2016 07:22 AM

Quote:

Originally Posted by oldave79 (Post 2846050)
With all faucets turned off, pressure read 85. With a faucet running, it read 60.

I adjusted pressure reducing valve. Now with all faucets turned off, it still read 85. With a faucet on, though, it read 40, and the pressure coming out of the faucet was obviously reduced. That said, when I first turned on a faucet, the pressure would be higher, and then quickly drop off to the noticeably low pressure.

Does this indicate a faulty pressure reducing valve or a bad pressure gauge, or something else? I would like to set my pressure at 60.

Thanks for the input.

After making a down PR adjustment the line pressure downstream is still high until relieved by opening a faucet valve.

After the PR adjustment and you relieved the pressure by opening a faucet valve did the line pressure go back up?

oldave79 01-02-2016 10:21 AM

Raylo, the pressure rise after shutting off the faucet occurred within a few seconds. So it sounds like I may have a faulty expansion tank then too. Thanks for the insight on pressure reducing valves.

Yodaman, when I adjusted the pressure down, the pressure dropped significantly with a faucet open, but once the faucet was closed, it returned to 85, regardless of where I set the pressure. Very strange.

oldave79 01-02-2016 01:02 PM

I also checked the pressure on the expansion tank, and there was no air charge in it at all. I guess the builder used really lousy materials and/or did a poor job of installation for things to be failing this quickly.

Yodaman 01-02-2016 01:51 PM

Quote:

Originally Posted by oldave79 (Post 2847962)
Yodaman, when I adjusted the pressure down, the pressure dropped significantly with a faucet open, but once the faucet was closed, it returned to 85, regardless of where I set the pressure. Very strange.


Not strange. This is what I would expect with a bad PR. The pressure is reduced when a valve is open. Much like a shower might be affected by someone flushing the toilet. The line pressure drops when valves are opened. When all are closed pressure should return to the set pressure. In your case the PR is not reducing the line pressure. Time for a new PR or rebuild.
Good luck

oldave79 01-02-2016 02:14 PM

Thanks. The insight and consensus here has convinced me that the PRV is indeed not working correctly. I'm going to get a plumber out here next week to rectify and hopefully avoid the larger problems that can come with high pressure.

2x_Tom 01-02-2016 03:59 PM

A pressure increase due to a faulty expansion tank is a result of heating water. It would take longer then a few seconds for your water heater to bring the pressure in the house up so don't use that as a gauge for whether or not your expansion tank is bad. If you want to see for yourself turn your water heater off or to pilot and retest, it will not affect the pressure readings.

It is normal for pressure to drop when a faucet is opened. This alone is not indicative of a problem. A pressure drop of 25lbs however is more then normal, something isn't right. What type of water service do you have? Is it galvanized? I doubt it is if the house is that new but perhaps if it was a remodel they tied back into the old service. If it is galvanized it may be rusted closed so much that a drop that large is normal and the only way to fix it is a new water service. More likely your PRV is bad, has a clogged screen or something is stuck in it. Are all your main valves fully open? Is their anything else before the PRV, a wye strainer perhaps that may be clogged?

85lbs of pressure isn't that bad. Find out what kind of pressure you have in the street. If it's only 85psi I wouldn't bother with a PRV unless you are required to have one there.

oldave79 01-02-2016 05:01 PM

My plumbing is PEX. Only one main valve and it's open. From the comments here, it sounds as though the PRV is malfunctioning. Code here requires a PRV, and I have water filters installed that call for a max 75 PSI, one of which I noticed was cracked while I was servicing it, which is what generated the concern.


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