Thermal Expansion Tank Location

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by BobPip, Apr 19, 2008.

  1. BobPip

    BobPip New Member

    Messages:
    1
    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. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,806
    Location:
    New England
    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.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,253
    Location:
    Cave Creek, Arizona
    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.
  4. gear junkie

    gear junkie Plumber

    Messages:
    67
    Location:
    Virginia Beach, IPC country
    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.
  5. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,253
    Location:
    Cave Creek, Arizona
    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: Apr 21, 2008
  7. gear junkie

    gear junkie Plumber

    Messages:
    67
    Location:
    Virginia Beach, IPC country
    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.
  8. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    The PEX needs 18" The expansion tank does not.
  9. gear junkie

    gear junkie Plumber

    Messages:
    67
    Location:
    Virginia Beach, IPC country
    I already said you were right once. HJ- you want to get in on this action by telling the fng he was wrong?:D
  10. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    I'll hold him down HJ... Give him a couple of kicks!:D
  11. westcoastplumber

    westcoastplumber Plumbing Contractor

    Messages:
    115
    Location:
    los angeles
    I got your back Ben.....although I doubt you need it;):D
  12. Terry

    Terry Administrator Staff Member

    Messages:
    14,767
    Location:
    Bothell, Washington
    Here is an electric water heater installed on a foam pad, with expansion tank, and antisiphon valve.

    Attached Files:

  13. 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?

    Last edited by a moderator: Jun 12, 2008
  14. tradeteacher

    tradeteacher Business owner & Instructor

    Messages:
    1
    Location:
    Carmel, IN
    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/documents/thermxtrol/9015-087revDTXT.pdf Hope this helps.

    Paul
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,253
    Location:
    Cave Creek, Arizona
    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.
  16. MRC

    MRC New Member

    Messages:
    5
    Location:
    Seattle
    Hello all~

    Hey my line going from the expansion tank into the WH has the pressure fitting /nut on the WH end and solder off the expansion tank "t" fitting. This is a flex line and it has a slow drip/leak. (perfect for waterboarding;))
    The nut came off just fine but the solder will NOT let go.
    Question - The tank is vertical & above the intake line. Is there water 'trapped' in the line via vacuum?
    I have released the pressure from the expansion tank & still no dice.

    Help?.......
  17. Terry

    Terry Administrator Staff Member

    Messages:
    14,767
    Location:
    Bothell, Washington
    The only way you can heat and unsolder that connection is if there is absolutely no water and it's open to air.
    If you have a torch and a Male Adapter to solder back on, you can disconnect and bend the tubing downward to drain it out. Or just cut the pipe back behind the tubing and solder the MA there.
    Some flex connectors with 3/4 ends will work then. NO TEFLON TAPE. The flex connectors with have seals at the ends.
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