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  • Suburban 12G water heater pressure relief valve leaking

    I've got the 12G Suburban SW12DEL water heater in my 2020 Solitude 310GK. It has been leaking about a 1/2 cup of water each day from the pressure relief valve. I tried the temporary "fix" that is listed in the owners manual (removing water from the tank to create an air pocket) but that isn't working. Does anybody else have a leaking pressure relief valve? It looks like replacement valves are cheap is I'll just order one from Amazon and replace it.
    Last edited by bertschb; 12-05-2020, 01:26 PM.
    Brian & Kellie
    2020 Grand Design Solitude 310GK-R, FBP, MORryde IS, 1,460w solar and 540ah BBGC3
    2020 Ford F-350 Platinum SRW PSD Tremor, 60g TF fuel tank, Hensley BD3-F air bag hitch

    Previous setups:
    2019 Grand Design Solitude 373FB-R, 2019 Ford F-350 Platinum DRW Powerstroke, Hensley BD5 air bag hitch
    2016 Grand Design Reflection 318RST, 2016 GMC 3500 Denali SRW Duramax, Hensley BD3 air bag hitch

  • #2
    Brain - I'm not sure if the owner's manual method is the same as the one below. But it's worth a shot.

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    Jim and Ginnie
    2024 Solitude 310GK
    GDRV Technical Forum Moderator
    GDRV Rally Support Coordinator

    Comment


    • #3
      Hi Jim

      Yes, that's the procedure I followed but it didn't resolve the leaking. Does your pressure relief valve leak?
      Brian & Kellie
      2020 Grand Design Solitude 310GK-R, FBP, MORryde IS, 1,460w solar and 540ah BBGC3
      2020 Ford F-350 Platinum SRW PSD Tremor, 60g TF fuel tank, Hensley BD3-F air bag hitch

      Previous setups:
      2019 Grand Design Solitude 373FB-R, 2019 Ford F-350 Platinum DRW Powerstroke, Hensley BD5 air bag hitch
      2016 Grand Design Reflection 318RST, 2016 GMC 3500 Denali SRW Duramax, Hensley BD3 air bag hitch

      Comment


      • #4
        Originally posted by bertschb View Post
        Hi Jim

        Yes, that's the procedure I followed but it didn't resolve the leaking. Does your pressure relief valve leak?
        Mine was dripping very slowly until I performed the procedure which resolved it.
        Jim and Ginnie
        2024 Solitude 310GK
        GDRV Technical Forum Moderator
        GDRV Rally Support Coordinator

        Comment


        • #5
          UPDATE:
          After unsuccessfully using the factory recommended procedure to drain a portion of the water out of the tank to restore the air expansion pocket, I replaced the pressure relief valve. It is now leaking as well. I drained quite a bit of water out of the tank to replace the valve so I was hoping if nothing else, I'd get a few days of no leaking. No dice. Am I the only one that has this annoying leaking water heater that can't be resolved by draining water form the tank periodically????? This is my third Grand Design RV and I've never had this problem before.

          I'm going to have to reseal the outside compartment where my water heater is located because the factory sealing isn't very good. Since I have so much water leaking, I'm worried about it leaking past the poor caulking and causing water damage. I have some butyl tape, Eternabond and regular ol' silicone caulking. Which would work better for this application?

          Cate&Rob I seem to recall you added an expansion tank to your system. Do you think this would resolve my problem?

          I've set a small towel at the bottom of the compartment to absorb the leaking water for now. I ring it out a couple times a day.
          Brian & Kellie
          2020 Grand Design Solitude 310GK-R, FBP, MORryde IS, 1,460w solar and 540ah BBGC3
          2020 Ford F-350 Platinum SRW PSD Tremor, 60g TF fuel tank, Hensley BD3-F air bag hitch

          Previous setups:
          2019 Grand Design Solitude 373FB-R, 2019 Ford F-350 Platinum DRW Powerstroke, Hensley BD5 air bag hitch
          2016 Grand Design Reflection 318RST, 2016 GMC 3500 Denali SRW Duramax, Hensley BD3 air bag hitch

          Comment


          • #6
            bertschb
            Hi Brian,

            From your description . . . the water is leaking through the valve, not around the valve past the threads . . . correct? Your description sounds like a faulty valve, but having this happen to the original and now the replacement valve seems to point to some other cause.

            The first thing that I would do is open and "snap" closed the pressure relief valve (with water pressure in the system). Do this a couple of times. This will be a little messy (water spray) but is intended too flush any possible contamination from the valve seat that might be holding the valve slightly open. Then, relieve the pressure and re-establish the air cushion as discussed earlier. If the valve is leaking, the air cushion will go away very quickly and the valve will begin to drip water in a few hours.

            Back to the other possible causes . . . this is a "pressure relief" valve . . . is it possible that your water system is building sufficient pressure to trigger the valve to do what it is designed to do? You have probably read my many posts on the value of a system water pressure gauge. This would be an ideal thing to have in sorting this out. If pressure spikes from the campground water system are getting past your (presumed) inline pressure regulator, this pressure spike would be held in the RV water system by the inlet check valve. Do you sometimes get a "burst" of pressure when you open a faucet?

            I did install an "accumulator" tank (sometimes called an expansion tank). The primary purpose of this is to hold water at pressure so that the onboard pump runs for longer when it comes on (filling the tank) and cycles less frequently (while the tank supplies water). Both of these things are good for the longevity of the pump. As you may recall, I have made mention of the observation that filling and pressurizing the water system and then turning on the water heater will cause the system pressure to climb past 70 psi (without an accumulator tank). With the volume of the accumulator tank available to absorb the volume increase from water heating, the pressure rise is barely noticeable on the pressure gauge. All this to say that if the "leaking" pressure relief valve is actually opening because of an over-pressure situation (which it is supposed to do) an accumulator tank would help. If it is a faulty valve, this tank will not solve the problem.

            You need a pressure gauge T'd into any cold water line or even attached to the cold water low point drain, to tell you what is going on.

            Rob
            Cate & Rob
            (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
            2015 Reflection 303RLS
            2022 F350 Diesel CC SB SRW Lariat
            Bayham, Ontario, Canada

            Comment


            • #7
              Cate&Rob

              Thanks so much for the response Rob. I think you've solved my problem.

              First, to reply to some of your questions. Yes, water was dripping from the valve, not around the threads. I watched it dripping this morning. I did snap both the old and new pressure relief valves shut. This leaves us with....

              Water pressure!

              One thing I've whined about for years is the "low water pressure" in our Grand Design RV's. You've probably read my posts about this. I bought an adjustable water pressure regulator when we bought our Reflection five years ago and used it everywhere we went. After trying all sorts of things to improve the water pressure for showers, I finally stopped using the water pressure regulator at the last two RV parks we visited prior to arriving at our spot here in Palm Springs this fall as an experiment. We now had a residential shower experience!!!! My wife was ecstatic! Me too! The one thing that reminded us each day that we were living in an RV was gone!

              After your post this morning it reminded me I actually purchased a water pressure gauge (not regulator) a few months ago but had never used it. I decided to dig it out of storage and see what our water pressure was. I was stunned. 90psi!!!! I've never seen water pressure this high. Now this is a cheap Rain Bird gauge but if it's accurate, it would explain my problem with a leaking pressure relief valve.

              I'm ashamed to admit that I missed an obvious clue earlier. I had a 3' section of hose that I leave connected to my Nautilus panel with a quick disconnect on the other end. I do this so when I disconnect my fresh water hose when breaking down camp for traveling, water doesn't drip from the Nautilus panel connection onto my black and gray tank gate valves. I noticed this short 3' hose had swelled. I have an identical looking short hose connected to my water softener and it looked fine so I figured it was just a cheap hose and replaced it. I'm pretty sure I know why that hose swelled and now I'm wondering what all the soft hose looks like in my RV. The last time I looked in the basement for leaks (I do this periodically), the hoses looked fine but I'll check them again at some point here soon. I'll need to take some Tylenol in advance to prepare my body for the gymnastics required to get back in there.

              Anyway....I'm pretty certain excessive water pressure was my problem. 90psi is a lot! I drained water from the water heater again to recreate the air expansion pocket. The water pressure regulator is set at 55psi. It drops to 40psi with a faucet open. This is at the post before my water softener, not T'd into a cold water line. If I can find the correct fitting, I think I'll buy another pressure gauge and "T" it into my cold water line under the bathroom sink.

              I hope I haven't done any permanent damage to the plumbing. Our desire for decent shower experiences clouded my judgement. As my wife said this morning - "The party is over!" I'm back to using water pressure regulators and now I have a good example for others as to why they should use them.

              Thanks again for taking the time to reply! I'm going to go dribble some water out of the kitchen faucet to wash my coffee mug...

              Brian & Kellie
              2020 Grand Design Solitude 310GK-R, FBP, MORryde IS, 1,460w solar and 540ah BBGC3
              2020 Ford F-350 Platinum SRW PSD Tremor, 60g TF fuel tank, Hensley BD3-F air bag hitch

              Previous setups:
              2019 Grand Design Solitude 373FB-R, 2019 Ford F-350 Platinum DRW Powerstroke, Hensley BD5 air bag hitch
              2016 Grand Design Reflection 318RST, 2016 GMC 3500 Denali SRW Duramax, Hensley BD3 air bag hitch

              Comment


              • #8
                Thanks for the follow up Brian. Yep, 90 psi is really high. PEX lines should be able to handle this, but I'm not so sure how the braided hose will stand up.

                I'm still a little confused on why the pressure relief valve would be leaking. RV pressure relief valves are factory set for 150 psi. I think it would be unusual (not impossible) for 90 psi to cause it to leak.

                Another possibility is that the water heater temperature is too high and the system is building up excessive pressure. If that's the case, the pressure relief valve is doing it's job. I wonder how hard it would be to measure the pressure in the hot water side of things?

                Jim
                Jim and Ginnie
                2024 Solitude 310GK
                GDRV Technical Forum Moderator
                GDRV Rally Support Coordinator

                Comment


                • #9
                  Originally posted by TucsonJim View Post
                  I wonder how hard it would be to measure the pressure in the hot water side of things?

                  Jim
                  Hi Jim,

                  I was in the middle of writing that the pressure on the hot side will be the same as on the cold side . . . and then, I remembered the Nautilus required check valve on the water heater output. This could retain a higher pressure in the hot water half of the system. (The Kantleak system does not require or have a check valve on the water heater output.)

                  One could compare pressures between hot and cold systems with a pressure gauge attached to the hot or cold low point drains.

                  Rob

                  Cate & Rob
                  (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                  2015 Reflection 303RLS
                  2022 F350 Diesel CC SB SRW Lariat
                  Bayham, Ontario, Canada

                  Comment


                  • #10
                    Originally posted by Cate&Rob View Post

                    Hi Jim,

                    I was in the middle of writing that the pressure on the hot side will be the same as on the cold side . . . and then, I remembered the Nautilus required check valve on the water heater output. This could retain a higher pressure in the hot water half of the system. (The Kantleak system does not require or have a check valve on the water heater output.)

                    One could compare pressures between hot and cold systems with a pressure gauge attached to the hot or cold low point drains.

                    Rob
                    Rob the water heater check valve is a one way valve to let water flow out and keep anti-freeze from flowing back in during the winterize function. Theoretically, if the check valve malfunctioned, the pressure in the tank could build and pressurize the system to the point that the pressure relief valve opened. But if the check valve wouldn't allow pressure to equalize between the tank and the plumbing, there would little to no hot water flowing out of the tap.

                    Checking the pressure differences between the hot and cold sides is a great idea. There's got to be a way to temporarily plumb in a pressure gauge on one of the faucets.

                    Jim
                    Jim and Ginnie
                    2024 Solitude 310GK
                    GDRV Technical Forum Moderator
                    GDRV Rally Support Coordinator

                    Comment


                    • #11
                      Hot and cold water pressure will be the same since the inlet to the water heater is the common cold water connection. The hot water line(s) upstream of the water heater outlet check valve will not be pressured higher unless some other heat source heats that line to a temp higher than that of the water heater.
                      I have on occasion plumbed a pressure gage into the outside shower outlet to see how high system pressure gets as water heats, expands and causes rising system pressure. I have seen pressure reach the water heater relief setting. I installed an expansion tank to give the expanding water some place to go without creating excess pressure and no relief valve drips. The expansion tank was installed connected to the water pump outlet. A point common to the cold water side of the system.
                      Ted
                      2021 Reflection 310RLS
                      2020 F350 PS,CC,LB,SRW

                      Comment


                      • #12
                        TucsonJim TedS

                        If the water system is over pressurized by inlet pressure or water heating, a properly functioning water heater output check valve could hold this higher pressure in the hot water plumbing, even if the pressure in the water heater and cold water system were allowed to drop such as by opening a cold water faucet. Cold water and water heater pressure could be dropped to zero and if the check valve is functioning properly it would hold pressure in the hot water system.

                        Rob
                        Cate & Rob
                        (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                        2015 Reflection 303RLS
                        2022 F350 Diesel CC SB SRW Lariat
                        Bayham, Ontario, Canada

                        Comment


                        • #13
                          Cate&Rob
                          I haven't used my quota of dumb questions for the day, so....

                          A quick internet search suggests our RV's water heaters (WH) have a 130 degree F thermostat. Apparently there is a safety that shuts down the WH at 180. If the temp is higher than 130 but not over 180, will that increase in temperature build more pressure in the tank? In other words, what would happen if the water routinely got to 150 degrees? 160? Could the increased temp cause the safety valve to slowly relieve pressure?

                          Can running hot water into a small container and measuring the temp with a meat thermometer verify WH performance?

                          ​​​​​​​Any difference expected between gas and electric?

                          Howard
                          Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                          2017 Ford F-350 DRW, '19 315RLTSPlus

                          Comment


                          • #14
                            In a closed water system with no expansion volume, pressure will increase with temperature. Occasionally opening either hot or cold faucet while water is being heated will drop water pressure and keep the water heater tank valve from dripping. I read somewhere, can't find the article, that the water heater volume will increase about a cup when rising from around 65F to around 120F.

                            No difference whether gas or electric heat.

                            If we did not have the city water inlet check valve, the water pressure would never rise high enough to open the relief valve. The expanding volume would back out to the city water supply system.
                            Ted
                            2021 Reflection 310RLS
                            2020 F350 PS,CC,LB,SRW

                            Comment


                            • #15
                              If I recall some of the burst soft hoses were red indicating that they were on the hot water side. Could all of this new information on the hot water pressure be a light to shine on the failing of the soft hose? Folks that are full time or set up in a park for extended periods would have there water heater on most if not all of the time , could this also be a link to pressure building in the system and possible cause of soft hose failure?
                              Do some recent soft hose replacement I have found that there have been no large bulges at the fittings. I have also found that once the pex clamp is removed it take a pretty good pull to get the soft hose off of the pex fitting.

                              Brian
                              Brian & Michelle
                              2018 Reflection 29RS
                              2022 Chevy 3500HD

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