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Water heater expansion tank mounting

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sre92
sre92 Member Posts: 13
in Domestic Hot Water

What do people think of water heater supply valves meant to hold expansion tanks, like this one?

https://www.supplyhouse.com/Webstone-H-21653W-3-4-FIP-Union-x-MIP-Pro-Pal-Dielectric-Water-Heater-Supply-Valve-w-Expansion-Tank-Service-Ball-Valve-Lead-Free

My water heater currently doesn't have an expansion tank. I don't have any check/backflow prevention from the city supply right now, so there's no huge concern there, but I'd like to be able to safely shut off the main water valve for extended periods, so I want to add an expansion tank. My water heater is under a fireplace hearth, so if I support an added expansion tank from above, I'd either have to locate the exp tank farther from the water heater than I'd like (long dead leg) or drill into cement (I'd rather not).

Three above fitting/valve supports the tank from below, but not by the body of the tank. Would you consider using that in my situation?

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,800
    edited January 30

    If you are closing off the water feed to the whole house, you should also shut off the burner or element to the water heater. Then you will still not need an expansion tank. I don't see any reason to have the water to the entire home/building shut off and continue to heat the water in the water heater. Can you?

    But to answer your question, that tank holder will carry the weight of the tank under normal use since it should never actually be full of water. You want to be sure that the pipe connecting to the water is properly supported as soon as you get past the masonry ceiling.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    sre92
  • hot_rod
    hot_rod Member Posts: 27,116

    I'd limit the, length of the line to the tank as it could be a bacteria breeding ground.

    What about a bracket like this?

    Screenshot 2026-01-30 at 2.14.41 PM.png

    Screenshot 2026-01-30 at 2.14.50 PM.png
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    sre92
  • Intplm.
    Intplm. Member Posts: 2,932

    They are pretty darn good. @sre92 the one you posted and the one above that @hot_rod has shown. They support a tank A LOT more than any pipe can. They support the tanks real well. Especially when the tank fails and is water logged.

    sre92
  • sre92
    sre92 Member Posts: 13
    https://forum.heatinghelp.com/discussion/comment/1885355#Comment_1885355

    Yes, the water heater should be turned off, but I'm not always the last one to leave the house for a weekend or an extended trip. I can give instructions to turn one lever, but probably not how to turn the water heater off all the way.

  • hot_rod
    hot_rod Member Posts: 27,116

    I think most all water heaters have a vacation setting. That allows them pilot to stay on, but the burner should not fire..

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,800
    https://forum.heatinghelp.com/discussion/comment/1885380#Comment_1885380

    Understood. Teenagers can be so unreliable …as can spouses. Good idea for the expansion tank! It makes the job stupid proof.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Larry Weingarten
    Larry Weingarten Member Posts: 4,042

    Hi, If the water is going to be shut off, maybe also open a tap (best physically higher than the top of the tank, like a shower) and let it drip to relieve any possible pressure? 🤔

    Yours, Larry

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