Recommendations for proper way to install expansion tank with new water heater

Discussion in 'Water Heater Forum, Tanks' started by DoofusOfTheDay, Jul 27, 2011.

  1. DoofusOfTheDay

    DoofusOfTheDay Member

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    Well, I live in a neighborhood about 15 years old. My next door neighbor's gas water heater just failed, as well as my neighbor across the street. Of course the builder didn't spend the extra nickel to put a pan and drain pipe under water heater so I am scared mine failing and damaging all kinds of stuff I have. I know how to sweat pipes and have actually installed a water heater in my old house, but haven't had to deal with expansion tanks, as they are new code requirement. So, I took a look at how my next door neighbor's water heater was installed by professional plumber. The plumber installed the expansion tank horizontally(tank horizontal attached to vertical pipe) which Watts literature says is okay - http://media.wattswater.com/2915054.pdf but only if you support the tank. He didn't, it is just hanging there screwed into T-fitting. I have 2 options to install expansion tank when I buy new water heater next week. If I install the expansion tank vertically, I would have to extend the cold water supply a few feet on the ceiling, and then drop it straight down and back to the water heater. Would that be the best way to install the expansion tank, or should I just install it horizontally? If I do install it horizontally, what is the proper way to brace the expansion tank, given that the support would have to come from the ceiling? The closest wall is a foot or so away and is concrete that I'd rather not tap into.

    Thanks.
     

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  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

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    Install it vertically. When installed horizontally and the bladder fails the tank fills with water and becomes to heavy to support itself.

    John
     
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  4. hj

    hj Moderator & Master Plumber Staff Member

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    If you, or anyone else, installs an expansion tank horizontally, it MUST have a support of some kind fastened to the ceiling. The ONLY way to install it safely without a support is hanging downward from the pipe in a vertical orientation. If it is "upward" gravity will still try to break it off once it fills with water.
     
  5. DoofusOfTheDay

    DoofusOfTheDay Member

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    Thanks for the replies. I had another thought on installing the expansion tank. Is there any reason why I shouldn't install it in the supply line strapped to the ceiling, like just before the elbow that brings the supply line down to the hot water heater? I don't see anything that says how near the water heater the expansion tank needs to be, so if I installed in the supply line on ceiling it would be probably 5-6 feet from the water tank connection.
     
  6. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

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    That is fine as long as it between the valve and the heater. You don't want to be able to isolate the tank from the heater by turning off the valve.

    John
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    You could strap it (the easier way normally), or build a shelf to set it on. Water weighs about 8#/gallon, so when it eventually fails, that's probably in the order of 25# or so hanging there. If it is hanging down, you won't spill much when you unscrew it. Sitting horizontal, it will dump some water when you unscrew it.
     
  8. Gary Swart

    Gary Swart In the Trades

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    If your pipes are a the ceiling and run across the floor joints, center the tank between joints and strap it to the joints on each side. Somewhat like your Plan B drawing except the tank would be at ceiling height. Plan A would require designing a platform or some kind of support to the tank. No point in doing that.
     
  9. hj

    hj Moderator & Master Plumber Staff Member

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    Technically, the tank can be installed anywhere in the house, but ideally it should be connected between the heater's water valve and the heater.
     
  10. DoofusOfTheDay

    DoofusOfTheDay Member

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    I like the idea of just strapping it all to the ceiling joists. I'll put new shutoff valve just upstream of it too. I know it will be a bit awkward to get at the shutoff valve in this setup, but not like I need to get at the shutoff a bunch of times every year anyway! My wife thinks I am over engineering this and installing the expansion tank horizontally even if it failed and filled with water would be no big deal. That's probably true, but there must be a good reason why the manufacturer says don't do this unless supported properly.
     
  11. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

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    The tanks are made of a light weight steel and can sear off at the point of connection when the bladder fails and the tank fills with water.

    John
     
  12. DoofusOfTheDay

    DoofusOfTheDay Member

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    New water heater in including expansion tank. Expansion tank seems to have resolved our issue when we initially turned on shower would be a big rush of water, and then it would settle down to static pressure. Thanks all!
     
  13. TxFLSTC

    TxFLSTC New Member

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    Most if the info on the web indicates that you can install
    an expansion tank vertically up or down, or horizontally
    sideways, or even on a 45 degree angle, anywhere on
    the cold. While technically correct, it seems to me that
    tank up, connection at the bottom, close to & above the
    HWH intake would be best;
    Water would drain out of the tank, eliminating or reducing stagnate water.
    Semi stagnate water would go into HWH, hopefully sanitized, >140, not into cold drinking water.
    Completely drain each time system de-pressurized = no stagnate water
    Would still function if bladder broke.
    Bladder could still be checked by de-pressurizing system, if tank psi holds bladder ok.
    Would drain out when replacing = low weight.
    Thoughts ?
     
  14. Master Plumber Mark

    Master Plumber Mark Master Plumber

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    Usually we will install them on the cold line going into the water heater...
    its always best to figure out a good way to support them ... I prefer to use a tee on the top of the heater
    and install the therm tank onto this fitting.... placing a support leg under the arm.... I really dont care for them
    because the seem to become water logged before the water heater fails and are worthless.. No one checks them
    and maintains them .....[​IMG]
     

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  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Whenever water is forced into the ET, whenever you later open a valve, the bladder in the tank pushes out that stored water, so it is exchanged on a regular basis regardless of orientation. Install it in any orientation the manufacturer allows, but also support it properly, as it will fill with water once the bladder fails and will become quite heavy. How long that is depends on a lot of factors such as the static pressure, the frequency of hot water use (how often the bladder stretches), and your water chemistry.
     
  16. Master Plumber Mark

    Master Plumber Mark Master Plumber

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    have you ever had a 5 gallon thermal expansion tank filled with water fall and land on your foot??
    They are quite heavy and come down like a ton of bricks.... normally you get a good bath when you cut one out of the system....
     
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    They're only heavy when they fail! This is why they need to be properly supported. Under normal circumstances, if you've precharged it properly, they do not hold much water, and when they do (after a WH reheating cycle), when you open a valve to use hot water, that gets pushed out by the bladder for the most part. If the precharge equals the actual water pressure, the bladder will sit at its neutral point, and not be holding much of anything. When the heated water expands, it compresses the bladder, but if it is large relative to the amount of water, the pressure doesn't rise much at all. If it is undersized, or underinflated, you'll have lots more water in it most of the time, and stretch it further than design, decreasing both its effectiveness and life, and, have a larger pressure change in the process.
     
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