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Okay to not install expansion tank for domestic?

sunlight33 Member Posts: 330
If there is no backflow preventer installed on city water, is there any benefit to install an expansion tank (for indirect water heater)? I have been living in my house for several years and recently I have a chance to redo the plumbing so I am wondering if I should take this opportunity to add a tank.


  • pecmsg
    pecmsg Member Posts: 2,017
    Add the tank. Eventually you’ll get a back flow preventer. 
    JUGHNE Member Posts: 8,368
    Or if you add a recir system for DHW you would need a check valve on the cold.
    I would add a tee for future connection of the tank. Even a tee with a valve so you would not have to drain down to add or change tank.
  • dopey27177
    dopey27177 Member Posts: 540
    Why add the tank?
    Install the back flow preventer, do not forget that probably is a code item and will need a plumber with a lic. or certification.

    Also do what Jughe said, future also find ways to jump up and and become now.

    EBEBRATT-Ed Member Posts: 9,104
    What @JUGHNE said.

    I wouldn't add a tank unless you have to. Just another thing to have to maintain and eventually fail
  • sunlight33
    sunlight33 Member Posts: 330
    Yeah I will probably add a tee with a threaded cap.
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,181
    Hi @sunlight33 , What's the static pressure you're working with?

    Yours, Larry
  • sunlight33
    sunlight33 Member Posts: 330
    50 psi
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,181
    Hi, with that pressure, I see no reason why a reducer or other backflow device will be needed any time soon. Simple is good. I’d skip the expansion tank. o:)

  • hot_rod
    hot_rod Member Posts: 14,797
    It's not uncommon for the water utility to upgrade the meter or meter yoke to a BFD type, then you will see relief valves start seeping or pop off.

    Install a stainless or bag type expansion tank and it will probably outlast the tank.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • ChrisJ
    ChrisJ Member Posts: 11,612
    I wouldn't add anything that's not needed.

    Maybe they will require a BFP, maybe they won't and if they do no one knows how many decades from now it could be.

    If it does happen do what's required at the time and you'll have a nice new tank then.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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