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Thread: Well and Hot Water Expansion Tank

  1. #1

    Default Well and Hot Water Expansion Tank

    I live where we are governed by UPC. I have a standard well system (not constant pressure) that operates between 30-50psi. The system is closed because there is a check valve where the water supply enters the house. Does my hot water heater need a small expansion tank? Isn't the well tank an expansion tank? The only way I could see needing the small expansion tank at the hot water heater is if there was a check valve on the cold water supply to the hot water heater. I recently rented a house with a similar standard well system and it had an expansion tank on the hot water heater. If I do need a small expansion tank on the HWH, what pressure do I set the expansion tank at 30 or 50psi?

    Thanks,
    Mike

  2. #2
    Plumber Sandpiper Plumbing's Avatar
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    Default

    Yes, you need the expansion tank on the water heater. Where we're located, the check valve into the house is not required and the heated water can expand back into the well pressure tank. But, if you have a check valve on the water line as it enters the house, you're preventing any expansion back to the well pressure tank and you need the expansion tank at the heater. Most exp. tanks are pre-set at 40psi. I'm sure many here would change depending on the pressure switch settings at the well equipment but not me, I'd leave it at the 40, it'll do it's job.

  3. #3
    Master Plumber Redwood's Avatar
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    The pressure on the expansion tank Should be set to 50.

  4. #4

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    But, if you have a check valve on the water line as it enters the house, you're preventing any expansion back to the well pressure tank and you need the expansion tank at the heater.
    Thanks for your response. In my case, the well expansion tank is in my basement downstream from the check valve. So, the hot water heater is connected directly to the well tank.

    Mike

  5. #5
    Plumber Cass's Avatar
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    If the bladder tank is on the house side of the check valve it will take care of the expanded water...if the bladder tank is on the well side of the check valve then you would need an expansion tank...

  6. #6

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    If the bladder tank is on the house side of the check valve it will take care of the expanded water
    The bladder tank is on the house side. Thanks for your help.

  7. #7
    Master Plumber nhmaster's Avatar
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    The UPC and the IPC do not differentiate between a well system and city water supply where installation of a thermal expansion tank is required.

  8. #8

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    The UPC and the IPC do not differentiate between a well system and city water supply where installation of a thermal expansion tank is required.
    My question is does my 120gallon bladder tank qualify as a thermal expansion tank? In my opinion it should, but I am not a plumber.

  9. #9
    Master Plumber nhmaster's Avatar
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    Does your 120 gallon water tank say "thermal expansion tank" on it anywhere?

  10. #10

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    Does your 120 gallon water tank say "thermal expansion tank" on it anywhere?
    No, it does not. It is a standard well bladder tank.

    I am starting to get the feeling that there is not a consensus on this subject.

    IMO, If I put a small expansion tank on my HWH and set it a 50psi, it is never going to do anything except take up space and rust. Any expansion of the HWH water is going to be absorbed by the 120 bladder tank. But, the code might dictate that I have this decoration in my system and that is the question I am trying to get answered.

  11. #11
    Master Plumber nhmaster's Avatar
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    I believe that you did indeed answer your own question. However stupid some of these things seem (read my signature) they are still a requirement. It's a lot like spending the day at the DMV.

  12. #12
    General Contractor Carpenter toolaholic's Avatar
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    Cool

    He makes a good point Master. Expansion tanks arn't required everywhere!
    I think they are in Wash state.

  13. #13
    Master Plumber nhmaster's Avatar
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    The IPC requires them as does the UPC and the Nat Std code but after that I can't say. By the way your local jurisdiction may ammend the requirements of the state adopted code but only to the effect of making the requirement more stringent not less. So if your state code is ipc and the local inspector says he doesn't want an expansion tank, he's wrong and his ruling will not hold up in court. Doesn't happen very often because most towns and cities don't want to be bothered with the legal implications of implimenting their own codes.

  14. #14
    TROJAN WORLDWIDE SALES RP MACPLUMB 777's Avatar
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    Default Hot Water Expansion Tank

    I Disagree With Nh Master On This Issue,
    I Think If You Want His 120 Gal. Well Tank To Be Approved As Thermal
    Expansion All He Has To Do Is Get A Stencil Kit And Paint It On
    The Side Of His Well Tank
    The Point Is The Physical Construction Of Both Tanks Is The Same As
    They Are Both Made For Potable Water To Expand Into
    So As Long As There Is "no" Check Valve Between The Two I Think It Would Be Approved For That

    MACPLUMB 777

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    35 YEAR MASTER PLUMBER, HEATING, ELECTRIC, DRAINS, FIRE SPRINKLERS, WATER HEATER
    AND BOILERS SINCE JAN, 1989

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  15. #15
    Master Plumber nhmaster's Avatar
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    Hate to argue with you but I'll bet you can't find stencling the tank in the code book nor can you find an astm or any other approval for use as a thermal expansion tank on the well tank. It's all about liability baby.

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