Announcement Announcement Module
Collapse
No announcement yet.
HW Heater Temp/pressure relief valve Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • HW Heater Temp/pressure relief valve

    With company here for the weekend I turned the temp up on the hot water heater. I guess I turned it up too high because the relief valve opened and made a big puddle. I put the temp back down and opened/closed the valve a few times but the thing continues to drip slowly. Besides replacing the valve, is there anything else I can do?

  • #2
    some times when you open and close it the drip may stop'

    i would replace it anyway .
    make sure turn off the gas or electric before you drain the heater.
    Charlie

    My seek the peek fundraiser page
    http://observatory.mountwashington.o...nal&fr_id=1040


    http://www.mountwashington.org/weather/conditions.php

    new work pictures 12/09
    http://public.fotki.com/hvachawk/

    Comment


    • #3
      Originally posted by schreibdave
      With company here for the weekend I turned the temp up on the hot water heater. I guess I turned it up too high because the relief valve opened and made a big puddle. I put the temp back down and opened/closed the valve a few times but the thing continues to drip slowly. Besides replacing the valve, is there anything else I can do?
      Turning the temp up based on more people in your house is dumb-*** at best. What you would be dealing with is a volume problem, which is not solvable by higher heat. As a matter of fact, this can be dangerous and can have a wearing effect on your fixtures.

      Change the T & P valve, if it is blowing water, and lower the temp. to below 120F.
      the dog

      Comment


      • #4
        Thanks for the quick replys. Turning the temp up allows us to mix in less hot water and use more of the cold water when we shower. That means we can get more shower time in before the tank runs cold. Might be dumb, but if it works ...

        As for wear and tear on the fixtures - protecting my fixtures doesn't do me a lot of good if it means taking a cold shower.

        Comment


        • #5
          To paraphrase Ben Franklin: Fish and company tend to get ripe after three days
          A few cold showers will move them on their way!! I hope you're not feedin' them. You may never get rid of them!!

          A tidbit of trivia: Over 140 degrees farenheit, the corrosion rate of metal doubles for every 10 degrees. That means twice the rate at 150, 4 times the rate at 160, and 8 times at 170. Where the metal is thinnest (threads, bends, etc) is where it will leak first. A leaking water heater or hot water pipe may mean a lot of cold showers before its all said and done! Higher heat also speeds deterioration of plastic.

          My $.002
          Practicing at practical wood working

          Comment


          • #6
            replace the t and p valve. Opening it on a water heater older than a year will almost always result in it leaking and not shutting all the way. DO NOT attempt to make the current valve quit leaking. If you succeed somehow, it may not work when it needs to and the heater could explode. It's a $7 part - replace it!

            Comment


            • #7
              Originally posted by schreibdave
              With company here for the weekend I turned the temp up on the hot water heater. I guess I turned it up too high because the relief valve opened and made a big puddle. I put the temp back down and opened/closed the valve a few times but the thing continues to drip slowly. Besides replacing the valve, is there anything else I can do?
              you are correct in your thery about turning up the temp, and using more cold and less hot
              the problem is that this is a short term quick fix. also can be dangerous to the young and elderly

              a pressure relief valve, combination temperature and pressure relief valve needs to be piped to a proper location, outside 6''-24'' off the ground. it can't be trapped and needs to grade away from the valve to prevent trapping any water against the spring, outlet of the valve.

              replace the valve and install an expansion tank on the cold water side, inlet to the heater. set it to the proper air pressure and you will be fine

              take a shorter shower with all these new guest

              rick.
              phoebe it is

              Comment


              • #8
                OK, I am goingto replace the valve. I watched it done once. Does the following sequence maske sense:

                1. Turn the thermometer to "pilot"
                2. turn off cold inlet
                3. drain the water from the tank (should be flushed anyway)
                4. remove the 3-4 ft threaded copper pipe that directs the H2O to the floor
                5. remove the valve by turning it counter-clockwise
                6. teflon tape the new one
                7. install the new one - how tight? Hand tight? until flush with the water hearter?
                8. turn the cold water back on
                9. set the temp to 120

                What does an expansion tank do? Thanks for all the help.

                Comment


                • #9
                  Schreibdave,

                  The reason I responded is that what you are doing is dangerous for two reasons:

                  1) If the T & P valve you had did not operate, which is possible, that heater could have been in an explosive situation.

                  2) You are creating a scalding danger for someone who turns on a faucet without knowing your situation.

                  In addition, plumbing fixtures are rated for a maximum temp of 120F.

                  Your theory is not completly wrong, but misguided.

                  A water heater is the function of volume and retention time. Yes, a higher temp. means less retention time, but raising it to above the maximum defeats the purpose because the T & P valve will kick-on relieving pressure and volume, which will lower the heat.

                  Raising the temp. below the maximum (a few degrees) will result in minimal effect.

                  What you are attepting to do is use a standard water heater as an on-demand water heater, which it is not designed to be.

                  If you have excessive company, I would sugggest a larger heater, or an on- demand heater.

                  But since you are obviously a genious, I'm sure you will figure it out.
                  the dog

                  Comment


                  • #10
                    Here's a Q&A paper from Watts Regulator on T&P valves which may answer some questions and provide some background on why T&P valves are needed.

                    http://www.wattsreg.com/pdf/F-52Q&A.pdf

                    This paper covers troubleshooting T&P valves and some basic information on installation (your local plumbing code takes precedence as always).
                    http://www.wattsreg.com/pdf/F-RV.pdf

                    Here's another about lawsuits associated with high water temps. If you think your friends won't sue you, wait and see. http://www.wattsreg.com/pdf/F-H20LS-Reprint.pdf

                    The paragraphs below from the above text get right to your issue and what PlumbDog is trying to make you aware of but you choose not to listen to those with years of experience:





                    With a 115°F maximum hot water supply, the mixture initially
                    has 76.9% hot water, and the percent hot water will have to be

                    steadily increased to maintain a 100°F mixed water from the
                    shower. With these conditions note that the allowable shower
                    time is 4 minutes but only 7.5 minutes for recovery, or 11.5
                    minutes cycle time. So that means 4 people can take a
                    comfortable 4 minute shower at a constant 100°F by gradually
                    increasing the percent of hot water from 76.9 to 100 over the
                    4 minutes, with a cycle time for 4 people of 46 minutes.

                    Next, consider the hot water supply to initially be at 160°F.
                    This extends the allowable shower time at a comfortable
                    100°F mix to 10.5 minutes, but the recovery time is extended
                    to 30 minutes, or 40.5 minutes cycle time per person.
                    This now then requires 162 minutes or 2 hours 42 minutes
                    total for 4 people to shower.

                    Net effect of all of these numbers is that turning a hot water
                    heater up from 115°F to the extremely dangerous temperature
                    of 160°F, the allowable time for shower increases
                    by 10.5/4 = 2.62, but the cycle time increases more, by
                    162/46 = 3.52. So for how long a shower should the installation
                    be designed?

                    Substantially increasing the allowable shower time is just
                    like asking for a cup of coffee from a fast food restaurant at


                    the standard 180°F holding temperature so that you will be
                    able to drive down the highway for another 100 miles with
                    hot coffee. Why not just buy a thermos bottle? Or stop again
                    for a refill of coffee that you can drink without burning your
                    mouth or suffering 3rd degree burns when you spill excessively
                    hot coffee on yourself?

                    If the shower time simply must be increased, then the solution
                    is to buy a larger capacity tank, and not to increase the
                    hot water supply temperature to extremely dangerous temperatures.
                    And the lower the heater temperature, the greater the energy savings.



                    Last edited by Bob D.; 05-08-2006, 06:29 AM.
                    ---------------
                    Light is faster than sound. That's why some people seem really bright until you hear them speak.
                    ---------------
                    “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
                    ---------
                    "Its a table saw.... Do you know where your fingers are?"
                    ---------
                    sigpic http://www.helmetstohardhats.com/

                    Comment


                    • #11
                      Thanks to everyone for the information. I have found religion and will not turn the temp up on my water heater to try to squeeze out more shower tiem. It's amazing how much information you can get on this site, just by asking a question. So much so that I went from being a "dumb***" one day to a "genius" the next - Right Plumbdog?

                      Comment


                      • #12
                        My way

                        I do it this way.


                        2. turn off cold inlet

                        4. remove the 3-4 ft threaded copper pipe that directs the H2O to the floor
                        4.5- Relieve pressure by opening TP valve
                        5. remove the valve by turning it counter-clock wise
                        (I have new one taped and doped and ready. I can remove and install a new one and only lose about a half cup of water)
                        6. teflon tape the new one, (I also use pipe dope)
                        7. install the new one - how tight? Hand tight? until flush with the water heater? (ummm, I never thought about it. I’ve replaced so many I just know)
                        8. turn the cold water back on
                        9. set the temp to 120

                        This may help.

                        Temperature Time to Cause
                        of Water a Bad Burn
                        -------------------------------------
                        150°F (66°C) 2 seconds
                        140°F (60°C) 6 seconds
                        125°F (52°C) 2 minutes
                        120°F (49°C) 10 minutes
                        One of the best lessons I learned from my father is when he did nothing to help me. I then learned to help my self.

                        Comment


                        • #13
                          Thanks for the advice. Coincidentally, as you were posting, I was in the basement changing the valve. I did it just as you described but I also drained the tank to wash out any gunk.

                          How do you test the water temp at the tank - open the relief valve? Afraid that if I do that. it will continue to drip. I have measured the temp at a 1st floor faucet and it's 113 degrees, so presumably a little hotter at the tank.

                          Comment


                          • #14
                            let the heater come up to the temperature that you set it for, then open the hose bibb at the bottom of the tank to get a reading into a 1 gallon can.

                            also reading the temperature from an actual fixture is good for a real life test. just make sure that the fixture you are turning on is a 2 handle fixture, all hot.

                            don't use a single handle mixing valve for this test.

                            i would start at 125. no more than 135.

                            rick.
                            phoebe it is

                            Comment

                            Working...
                            X