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  • Water pressure again

    Hi everyone,
    Haven't been here in a while. Just a general question about water pressure, if you remember I installed an expansion tank (thermal expansion problems) and I have a now 9 year old PRV. Just checked water pressure, which I do periodically, usually the highest it goes is 65 or so. I saw today it went to about 70 overnight. The expansion tank shouldn't allow the PSI to go over 20psi of the regulated pressure (which is between 45-47)? Otherwise I'm thinking it should be fine...yes?

    Thanks.

  • #2
    Re: Water pressure again

    What side of your PRV are you taking your reading from? if you are taking it before the valve that pressure can vary depending on the time of day, the house side of the valve should be CLOSE to what it was set at.

    >>>The expansion tank shouldn't allow the PSI to go over 20psi of the regulated pressure (which is between 45-47)?<<<

    The expansion tank has nothing to do with regulating the incomming pressure, its purpose is to make sure when your water heater is on it dosen't expand and cause the T+P valve to blow off (150lbs)

    Comment


    • #3
      Re: Water pressure again

      The house side pressure could increase all the way up to equal street pressure, and would be limited to that IF the pressure regulator is the bypass-type. Now, an expansion tank will try to limit that increase, but the ability of the XT to hold down the pressure would relate to the gallon capacity of the XT itself, and the size and temp. settings of the water heater.

      Comment


      • #4
        shacko

        spot on. spot on. breid.............

        Comment


        • #5
          Re: Water pressure again

          Thanks. I took the pressure on the downstairs sink, so after the PRV. Street pressure is usually 80psi (that's what the water company said), but okay if the expansion tank is only supposed to keep the water heater from blowing, I guess this is fine. Yeah it's set to between 45-50 basically so I guess this is working fine. Just checking.

          Comment


          • #6
            Re: Water pressure again

            put the gage back on and check the pressure. then open a fixture, hot and cold for a few seconds to watch the gage drop.

            if the pressure creeps back up towards 70#, then your regulator is bad. at 80# max. from the city main, i wouldn't worry about it. but also take a reading on the high pressure main to verify it bot at late night, early morning and daytime. the pressure could vary based on area demand.

            80# is the max. high before a regulator is required.

            also check your expansion tank to make sure it's pre-charge is still there and it's not water logged.

            rick.
            phoebe it is

            Comment


            • #7
              Re: Water pressure again

              If a valve is opened, pressure drops back down to the regulated pressure. I think the PRV is fine. Left the gauge on overnight again, highest pressure was again 70 ish and since people were using water during the night, the current pressure at 7 am was close to regulated pressure.

              How do I check the expansion tank? It was installed about a year ago, doubt it's bad, looks fine.

              Comment


              • #8
                Re: Water pressure again

                Didn't I install that expansion tank and pressure relief valve last year? This all sounds very familiar.

                The tank I usually install is pressurized to 40 psi. I don't remember pumping it up any higher but maybe I did. I would keep monitoring the pressure but 70 peak is nothing to worry about but you may want to think about a new pressure reducing valve sometime in the future. Average reliable lifespan isn't much over 10 years.

                Bill

                Comment


                • #9
                  Re: Water pressure again

                  Hi there,
                  Yes you did! It works great was just concerned about the pressure. But yeah, I get the feeling the PRV will need to be replaced sooner rather than later since it'll hit 10 years this November. I'll just keep monitoring in the meantime.

                  Thanks.

                  Comment


                  • #10
                    Re: Water pressure again

                    >>>How do I check the expansion tank? It was installed about a year ago, doubt it's bad, looks fine.<<<

                    Your expansion tank should be charged to the house side pressure of your PRV, should be charged without any water in it, just pump it up with a tire pump or something similar. It dosen't have to be perfect, just close.

                    Comment


                    • #11
                      Re: shacko

                      Originally posted by breid1903 View Post
                      spot on. spot on. breid.............
                      What Breid said!!!
                      Time flies like an arrow.

                      Fruit flies like a banana.

                      Comment


                      • #12
                        Re: Water pressure again

                        Originally posted by natalie1999 View Post
                        Hi there,
                        Yes you did! It works great was just concerned about the pressure. But yeah, I get the feeling the PRV will need to be replaced sooner rather than later since it'll hit 10 years this November. I'll just keep monitoring in the meantime.

                        Thanks.
                        You might be able to get a repair/rebuild kit for the PRV. Depending on the make model I suppose. Not much to them. I seem to recall repairing Watts U-5Bs a few times.
                        Time flies like an arrow.

                        Fruit flies like a banana.

                        Comment


                        • #13
                          Re: Water pressure again

                          Well, I think my PRV is not working properly. I watched the water pressure gauge after everyone stopped using water for the day. It's set for 45-50 but it was slowly creeping to 65 until it stopped. Water heater was not running so thermal expansion is out. PRV is getting 10 years old so I guess it's starting to go.

                          Do I repair it or replace it? It is a Watts N35B (3/4 I believe). I got quotes last year -- for PRV and replacing main shut-off valve to (I forget what it is called) a different, safer valve was running around $600-700. What to do?

                          Comment


                          • #14
                            Re: Water pressure again

                            To check an expansion tank:
                            1. Tap on the side of it with a screwdriver/wrench and go from top to bottom. As you get to the threaded side of the tank and preferable about half way under stagnet load you will here the tank sound hollow. If it does tank is most likely good. If test #1 fails then go to #2

                            2. Remove the cap on the air side of the tank and depress the schrader valve. If water comes out, the tank is done. If no air comes out, the tank is done.

                            3. If you have air at the Schrader, the tank is not that old, the PRV is good standards...then:
                            A. Shut down the water supply and open a faucet. Keep it open during the filling process.
                            B. Reset the pressure to with in 2# of the inlet supply pressure.
                            C. Restore proper operation.
                            Replacing an expansion tank:
                            1. Verify there is an operational PRV.
                            2. Measure delivered pressure to the house after any PRV.
                            3. Reset tank to +/- 2# of the delivered pressure.

                            Comment


                            • #15
                              Re: Water pressure again

                              Thanks Kevin but I do think expansion tank is working. It's only supposed to kick in when water heater is running, and the water pressure is not being maintained at a steady PSI even though water heater is not running.

                              I actually found an old quote for replacing PRV and main water valve to ball valve (someone recommended this to me a while back) for $295. Should probably give them a call tomorrow.

                              Comment

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