Expansion tank installation questions

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Vitaliy, Sep 6, 2005.

  1. Vitaliy

    Vitaliy New Member

    Sep 1, 2005
    Hi Guys,

    First of all, thank you all for very helpful replies.

    OK, couple days ago I installed pressure regulator to reduce city water
    pressure from 90+psi down to 50psi. Regulator is working fine but after it was
    installed I immediately realized I also absolutely have to install the expansion
    Watts DET 20 M1 expansion tank already ordered and it is on the way but
    I would like to be prepared for the installation. I think, I already figured out
    the answers but I would like to hear confirmations from very knowledgeable

    Here are my few installation related questions:

    - Watts is recommended just to hang this tank on the cold water supply
    pipe. In my case this will be next to impossible plus this tank will be very
    So, can I use some sort of support pedestal and put this thing on a floor?
    Can I buy somewhere this support pedestal or I have to build it myself?

    - Spec for the tank said this tank to be used on Direct Fired Gas/Oil/Electric
    water heater. I have Indirect Superstore 40 gallons water heater.
    I think this is not a problem.
    Am I right?

    - Tank comes pre-charged to the 40psi. I would like to maintain 50psi.
    Master_Plumber_Mark recommended to pump it to about 60 lbs
    (did he mean 60psi?). Watts recommended to pre-charge tank to the
    working pressure (my opinion is the same).
    What is the correct answer?

    - In order to prevent a lot of water to be wasted (if I have to drain my
    system for whatever reason) I think, it would be wise to install ball shutoff
    valve in series with tank and, of course, to keep it open all the time.
    Is this OK or strictly prohibited by code?

    - As a quick fix I will install (already ordered and hopefully before weekend)
    Watts "Governor 80-M1". This is toilet tank combination of fill valve and
    pressure relief valve, preset to 80psi. Eventually it will be first line of
    Do you have any experience with this product?
    If "yes" how good/reliable is it?

    Thank you,

    - Vitaliy
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    The tank will only get heavy when it fails...normally, it holds only a very small amount of water. Precharge it to your normal water pressure, and it will only accept water when it exceeds that amount (like when your water heater runs without a faucet open - which is why you need one in the first place!). The next time you open a faucet, that water will escape, and you'll be back to essentially empty. You might want to check the air pressure in the thing periodically, but they don't usually leak (I've not had a huge amount of experience in this, but mine haven't!).

    When (not if) the bladder in the tank fails, it will fill with water as the air is disolved in the water passing by. Then, it will be heavy.

    A shutoff to the tank is a good idea so when it comes time to replace it, you don't have to shut off the main supply. A ball valve here is great.

    You can install it basically anywhere it is convenient after the pressure reduction valve...doing it on the cold water will probably allow it to last a little longer.

    My unprofessional experience.
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