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Thread: Thermal Expansion Tank Location

  1. #1

    Default Thermal Expansion Tank Location

    I recently had a hot water heater and thermal expansion tank installed by a licensed plumber. I was not present at the install. But afterward I noticed that the thermal expansion tank was installed on the hot water side of the water tank.

    Will the expansion tank still work (reduce water pressure from thermal expansion) when installed on the hot water line? And if so, will it cause any problems having it installed this way?

    Thank you for any advice you can give.
    -Bob

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    It will work, but is not per the manufacturer's instructions. Was a permit pulled? Was the plumber licensed? Was it inspected?

    Installing it on the hot side will seriously decrease its life.

    Most inspectors, in the absence of a specific thing in the codes, fall back on the manufacturer's instructions...if it is not per those, the plumber should fix it for no cost, in my unprofessional opinion.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default tank

    An expansion tank will work no matter where it is installed in the system. Recommendations call for it to be in the cold water line adjacent to the water heater, and after the shut off valve. These requirements are to insure that the tank does its thing even under unusual conditions. The installation in the hot line can cause premature failure under specific conditions which may never happen in your case.

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    Plumber gear junkie's Avatar
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    premature failure will happen. even installed on the cold side, it needs to be 18" away from the the WH. I'd call the guy back up and show him the instructions on how to do the job right and have him do the job right or give you your money back.

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    Master Plumber Redwood's Avatar
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    Quote Originally Posted by gear junkie View Post
    premature failure will happen. even installed on the cold side, it needs to be 18" away from the the WH.
    Huh? http://www.watts.com/pdf/1915356.pdf

  6. #6
    Moderator & Master Plumber hj's Avatar
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    Default tank

    Good luck finding a spot 18" away from the heater to put the tank in this area. There is usually only about 12" from the wall to the heater inlet. I believe you are resorting to hyperbole to make your point. Whether there is premature failure or not depends on a slew of variables, such as the volume of water beneath the diaphragm, the temperature of the water, the presence of heat traps, etc.
    Last edited by hj; 04-21-2008 at 06:15 AM.

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    Plumber gear junkie's Avatar
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    Quote Originally Posted by Redwood View Post
    Thanks for the correction, we have a lot of pex here and that needs to be 18" away from the heater(that I'm sure of). I got the 2 mixed up.

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    Master Plumber Redwood's Avatar
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    The PEX needs 18" The expansion tank does not.

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    Plumber gear junkie's Avatar
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    Quote Originally Posted by gear junkie View Post
    Thanks for the correction, we have a lot of pex here and that needs to be 18" away from the heater(that I'm sure of). I got the 2 mixed up.
    Quote Originally Posted by Redwood View Post
    The PEX needs 18" The expansion tank does not.
    I already said you were right once. HJ- you want to get in on this action by telling the fng he was wrong?

  10. #10
    Master Plumber Redwood's Avatar
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    Quote Originally Posted by gear junkie View Post
    I already said you were right once. HJ- you want to get in on this action by telling the fng he was wrong?
    I'll hold him down HJ... Give him a couple of kicks!

  11. #11
    Plumbing Contractor westcoastplumber's Avatar
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    Quote Originally Posted by Redwood View Post
    I'll hold him down HJ... Give him a couple of kicks!
    I got your back Ben.....although I doubt you need it

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    Forum Admin, Expert Plumber Terry's Avatar
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    Here is an electric water heater installed on a foam pad, with expansion tank, and antisiphon valve.
    Attached Images Attached Images  

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    Plumber Sandpiper Plumbing's Avatar
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    We lay our expansion tanks on their side, right on the heater. We pipe in a tee a few inches above the cold nipple and screw the tank right into it. Other #2 used often around here is to mount the tank upside down right above the tee and use the bull of the tee to aim towards the back wall, turn up just past the tank, install your valve and pipe to the wall as your normally would.
    Hey Terry, what'd you use for the T&P drain? Almost looks like a flexible gas line? At first I thought it was a s.s. braided line. No reduction in pipe size there is there?

    Stainless steel water heater connector, similar in size to the copper flexes. It's just farther away in the picture.
    Last edited by Reader Review; 06-12-2008 at 06:01 PM.

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    Business owner & Instructor tradeteacher's Avatar
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    To clear up a few things posted above. According to Amtrol (manucafturer of thermal expansion tanks) they are required to be installed in the verical position. Although the instructions show the thermal expansion tank being installed on the cold water side, they are rated for upto 150 degrees and there is nothing in the instructions or warranty that prohibits them from being installed on the hot water side. I spoke to tech support at Amtrol and verified this information. Unless by local code there is no reason they cannot be installed on the hot side. Here is a link to the instructions http://www.amtrol.com/media/document...087revDTXT.pdf Hope this helps.

    Paul

  15. #15
    Moderator & Master Plumber hj's Avatar
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    quote; Here is an electric water heater installed on a foam pad, with expansion tank, and antisiphon valve.

    AND a corrugated flexible "hose" for the T&P valve which would NEVER be allowed in this area.

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