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  • Thermal Expansion Tank

    Dead ends in potable water systems are the worst. Code usually dictates this on water lines, but does not discuss the possibilities of devices that fail over time during use that can create large dead ends collecting water that has little or no introduction to potable water, given its design.


    The bladder inside these tanks break down due to chlorine content, pressure variations along with inappropriate pressure settings both on the air side of this tank, along with static line pressure entering the structure whether it be a pressure reducing valve set too high or no protection at all.

    Hard drops or "jolts" in the water system that can create a negative draw in a positive flow system can leach this harmful contaminate, which is water that made it past the bladder on the air side.

    Certainly, no one would want this in their plumbing system knowing how disgusting that is. I'm sure a water evaluation would definitely be descriptive of how harmful that is.

    http://www.youtube.com/watch?v=ske4M4-gS5A
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  • #2
    Re: Thermal Expansion Tank

    While I see your point in the water getting past the intended point in the tank, and sitting there... Is that not the same as when you turn on a hosebib that has been sitting for awhile? (galvanized water system)

    And it looks like to me, that if it takes a hammer, and a grown man to get this sorta water to come out of that portion of the tank, then it is likely going to stay there.

    Furthermore, if the water is getting past the bladder , is it not safe to assume that all the air inside the bladder is gone to? And any jolt or hammering action, is extremely unlikely to remove the contaminated water? Since a water system with zero air in it has NO PRESSURE, then how is a bladder completely full of water going to be affected by any syphoning? I guess it could, if it were to collapse the tank.

    If I am wrong, please clear this up for me!

    Comment


    • #3
      Re: Thermal Expansion Tank

      Originally posted by Macgoose View Post
      While I see your point in the water getting past the intended point in the tank, and sitting there... Is that not the same as when you turn on a hosebib that has been sitting for awhile? (galvanized water system)

      And it looks like to me, that if it takes a hammer, and a grown man to get this sorta water to come out of that portion of the tank, then it is likely going to stay there.

      Furthermore, if the water is getting past the bladder , is it not safe to assume that all the air inside the bladder is gone to? And any jolt or hammering action, is extremely unlikely to remove the contaminated water? Since a water system with zero air in it has NO PRESSURE, then how is a bladder completely full of water going to be affected by any syphoning? I guess it could, if it were to collapse the tank.

      If I am wrong, please clear this up for me!

      First part, yes. I've opened up lines to hose bibbs in copper that the water went bad and contaminates were present in the line. The location of a hose bibb can cause non-usage.

      The difference between the thermal expansion tank and the hose bibb is one is expected to be used and has the capability to be used to prevent a dead end in the potable water system.


      If you look closely, I was holding the camera in one hand and swinging the hammer in the other. I usually use my 32oz eastwing that will pound a hole in that thin steel in one correct throw. You are incorrect on it "staying there" because there is no separation of a membrane between potable and contaminate; it's been compromised.


      As far as your last statement, here is what I've found:


      I catch these tanks in all stages of being defective. There are times that the bladder side is still holding somewhat of a charge and when I pierce the tank I get literally sprayed with black smelly water.

      In reference to your statement about zero air,

      Air is compressible, water is not. Remember that there is still a membrane inside this tank moving back and forth with pressure fluctuations. It is however very minimal when the tank is completely full of water, and the tank "collapsing" is highly unlikely. I should test both the black water coming out of the one side, then test the clear water coming out of the other to determine the concentrations of contaminates.

      When the separation between potable water and any contaminate in the water supply becomes combined, it's a potentially dangerous situation. You've made it sound that water can get past the membrane but can't reverse back, and that's not true.

      Hook a water pressure gauge to any outside hose faucet/laundry tub in the house and start turning on multiple fixtures, or just one. Instantly there will be a negative drop in static pressure as the demand from another fixture lessens the pressure coming into the structure.

      This scenario explains why a second floor lav faucet seat screw can end up in the basement level laundry tub faucet...because it moved around in the water supply by where the constant give and take/push-n-pull in positive flow water systems is ever so common.

      Envision a nascar race and everyone is going the same direction, but a car starts to slow down and looks like he's going backwards in the path of cars. Still forward direction.


      I'm surprised with you being a service plumber you would question anything defective in a potable water supply, especially this situation, why you would think this is normal to leave in?

      Dead ends in the potable water supply are written into IPC/UPC/NPC as to be prohibited. This tank in failure mode is a dead end and more dangerous since people aren't aware of its dangers.
      Last edited by DUNBAR PLUMBING; 08-20-2009, 07:46 PM.
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      • #4
        Re: Thermal Expansion Tank

        Oh I am not saying that it needs to stay in the system, but looks to me like the circumstances to get that water out of the tank is pretty extreme. I agree completely that it needs to go.

        Just would be hard to convince me, if I were a customer, that any of that bad water had gotten into my water supply. I mean, you had to use a hammer.

        As for the water pressure thing. Lets just take worst case scenario. Bladder has completely failed. there is old nasty rusted water in the tank. Why would this reverse in pressure draw it out of the tank?

        (at this point it is arguing for the sake of arguing, it needs to be replaced)

        But how would a reverse in pressure, draw that old water out? Unless there was some life left inside the bladder, even then, when the basic pressure drop happens, water is coming out anyways and then it will not be setting there. I mean if the bladder is partly working, then any pressure drop is theoretically going to syphon water out of the tank. Why wouldn't it? there is a pressure drop which allows the bladder to expand back to its original size, thus expelling any water.

        Unless, the bladder is completely failed. Now how is water going to exit the tank without completely collapsing it? And why on earth would old water exit the tank, and let new water flow in? Same theory applies to when you take a full bottle of water, in lets say a pond, and raise the bottle to just where the neck is underwater. What happens? Without air, there is no pressure, except by weight of the tower.

        Without air, there is no reason that water will ever leave the tank. Nasty, yes. Am I convinced that it is any worse than any galvanized system? No.

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        • #5
          Re: Thermal Expansion Tank

          Let me ask you a question,



          How can water in positive flow systems go reverse in direction, even though the system is pressurized.




          If you are a service plumber, you know this answer. Watch the video again and watch the water leaving the tank on the threaded port, then view the contaminates on the other side of that bladder.

          Tell me if that bladder leaked water in the air side of the tank, how is that membrane preventing the slow saturation back into the other side.


          You might know more than me, at least your trying but the references to galvanized ???? has more than just me wondering why you're referencing a pond.

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          Comment


          • #6
            Re: Thermal Expansion Tank

            Originally posted by DUNBAR View Post
            Dead ends in the potable water supply are written into IPC/UPC/NPC as to be prohibited. This tank in failure mode is a dead end and more dangerous since people aren't aware of its dangers.
            I agree with your theory about the danger of dead ends in a potable water system but they're not prohibited under the IPC. Dead ends are prohibited for dwv. 704.5
            Buy cheap, buy twice.

            Comment


            • #7
              Re: Thermal Expansion Tank

              Knowing the hazards found with dead ends, why would the IPC glance over this known danger?

              I run under NPC (National Plumbing Code) and they limit stubouts on water lines to 4" on future baths or other fixtures.

              On DWV, ours is the same but sets limits at 2 feet.

              A dead end in a potable water supply is far more dangerous than in a drain waste vent system...and last fixture should always wash the vent, always.
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              • #8
                Re: Thermal Expansion Tank

                Gear is right, dead ends aren't prohibited under IPC. the explanation I was given was that a dead end is no different than a spare bathroom that never gets used.
                No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

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                • #9
                  Re: Thermal Expansion Tank

                  They make spun poly-well bladder tanks.

                  Dunbar or anyone, are they making the same in TXT yet? The contamination you see, I'm thinking it related to contact with metallic tank.

                  Would the contaminated water not be present in a non-metallic tank?

                  Just thinking...

                  J.C.

                  Comment


                  • #10
                    Re: Thermal Expansion Tank

                    Originally posted by JCsPlumbing View Post
                    They make spun poly-well bladder tanks.

                    Dunbar or anyone, are they making the same in TXT yet? The contamination you see, I'm thinking it related to contact with metallic tank.

                    Would the contaminated water not be present in a non-metallic tank?

                    Just thinking...

                    J.C.

                    I think the "black" is the lack of chlorine and the slow deterioration of the membrane, as it's slick like a flapper after years of the chlorine breaking it down.

                    Any water that sits stagnant in a water line, vessel/tank, it slowly starts to lose its protective qualities as the constant introduction of water movement through the lines is absent.

                    You guys that have pointed out that IPC doesn't prohibit dead ends in potable water supply...

                    Are you encouraging this as a good thing? It was a mistake to include it in my statement but at all costs, we plumbers need to understand that just because it isn't in your book, doesn't mean it doesn't pose a hazard.


                    I would say Mark (ToUtahnow) would have the final say which code (UPC/IPC/NPC) offers the best protection to the public and potable water systems as a whole.

                    IPC is lacking, heavily against NPC if they cannot figure out how dangerous dead ends are in potable water supply systems.
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                    Comment


                    • #11
                      Re: Thermal Expansion Tank

                      Originally posted by DUNBAR View Post
                      I think the "black" is the lack of chlorine and the slow deterioration of the membrane, as it's slick like a flapper after years of the chlorine breaking it down.

                      Any water that sits stagnant in a water line, vessel/tank, it slowly starts to lose its protective qualities as the constant introduction of water movement through the lines is absent.

                      You guys that have pointed out that IPC doesn't prohibit dead ends in potable water supply...

                      Are you encouraging this as a good thing? It was a mistake to include it in my statement but at all costs, we plumbers need to understand that just because it isn't in your book, doesn't mean it doesn't pose a hazard.


                      I would say Mark (ToUtahnow) would have the final say which code (UPC/IPC/NPC) offers the best protection to the public and potable water systems as a whole.

                      IPC is lacking, heavily against NPC if they cannot figure out how dangerous dead ends are in potable water supply systems.
                      Are you gonna' make me cut the celophane off my new book?!?!
                      I think the allowing of dead ends in distribution piping may not be as harmful as some think. The molecules of water don't know shape and will constantly move from areas of higher/lower temperatures and the potential and kinetic energy of the water held within the piping. So, in short, movement & mixing will occur in the piping. (Unless possibly there is a long vertical-dead-end run with the horizontal run at the top acting as a "busted tank" itself. Make any sense?)

                      But for a bladder tank there may be enough of a "body" of water that the typical movement in a distribution system will not keep it from becoming contaminated over a period of time. Especially if the tank is in the hanging position. The video seems to prove that to be the case.

                      J.C.
                      Last edited by BobsPlumbing; 08-20-2009, 09:45 PM.

                      Comment


                      • #12
                        Re: Thermal Expansion Tank

                        Originally posted by DUNBAR View Post
                        Let me ask you a question,



                        How can water in positive flow systems go reverse in direction, even though the system is pressurized.




                        If you are a service plumber, you know this answer. Watch the video again and watch the water leaving the tank on the threaded port, then view the contaminates on the other side of that bladder.

                        Tell me if that bladder leaked water in the air side of the tank, how is that membrane preventing the slow saturation back into the other side.


                        You might know more than me, at least your trying but the references to galvanized ???? has more than just me wondering why you're referencing a pond.

                        The tank was on it's side. Do I need to elaborate how it allows the water to "glug" out? I often try to explain things to my customers like this. If you can not see what I mean by the pond illustration, I am sure I can write out some huge exhausting post about the laws of physics and how water will not flow out of a vessel unless there is water flowing into it, or it has a form of vent.
                        And regardless, I never seen the contaminates come from the threaded port. And if they did, it was after the puncture, which just reinforces my stand on the fact that they will not enter the watersystem normally.

                        And I am sure no one is debating the safety of dead ends in the water system, yes they pose the potential for far greater contaminations than a dead end in the DWV system. Mere corrections about your reference to code.

                        I tend to see black water come out of hosebibs if they sit for a long time, or brown if left for a week or so.

                        Comment


                        • #13
                          Re: Thermal Expansion Tank

                          I'm gonna send you a bottle of this, it smells like ripe sewage, and you have to video yourself drinking it...not needing medical attention for the first 48 hours.
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                          Comment


                          • #14
                            Re: Thermal Expansion Tank

                            They were drinking the water in the system before you replaced it, are they ok? And I don't think you understand the power of oklahoma water man lol.

                            I'm just busting your balls, the vid is good reference for me, never woulda thought a tank would do that.

                            How old was that tank?

                            Comment


                            • #15
                              Re: Thermal Expansion Tank

                              Originally posted by Macgoose View Post
                              They were drinking the water in the system before you replaced it, are they ok? And I don't think you understand the power of oklahoma water man lol.

                              I'm just busting your balls, the vid is good reference for me, never woulda thought a tank would do that.

                              How old was that tank?


                              Tank was 7 years old, static water line pressure was 120psi @ 7pm when the majority of the subdivision was home.

                              I was there for 14' of copper water line that pinholed/cancered out from the inside.

                              When I found the high water pressure I sold the customer the necessity to install a PRV, I checked the thermal expansion tank and sure enough, defective.

                              Those tanks will not hold up to that high pressure, especially when the installers just take it from box to the water line. Those bladders are preset at 40 and with 120+ pounds extending it, excluding thermal expansion, it's going to fail.

                              This job was located where dual checks are installed in the meter brackets so it's automatic thermal expansion tank at the water heater.

                              This tank was installed hanging down from the ceiling with it incorrectly installed before the cold inlet valve to the water heater.

                              Code in my state is that it has to be between the shutoff and top of the tank, can run the line 50', just so it doesn't have a valve that isolates it from the device creating thermal expansion...as it will deem it useless.

                              The abundance of chlorinated water in the potable water system is most likely the reason why there isn't serious health issues.

                              But I've had people comment after I've taken out bad ones that the water didn't have an aftertaste like before.


                              I want everyone to hold a camera in one hand, swing a hammer in another and hold the camera as steady as I did in the video. I'll buy you an expansion tank if you can do it.
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