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Alternative to copper unions for stainless indirect water heater

Teratini
Teratini Member Posts: 13
edited September 2020 in Plumbing


I'm nearly ready to solder copper pipes to a new indirect water heater (Lochinvar SIT040) in California. I'm not a plumber, but am doing the job myself after practicing soldering for awhile.

I ordered 1" copper unions for the water heater, but they look a little beat up. Some have nicks on the area that creates a seal. After reading about the problems with copper unions, I'm looking for an alternative.

I could solder the pipes directly to the threaded copper adapter to the water heater (stainless male pipe thread), but what if the adapter leaks after everything is assembled? I'd need to drain the water heater, desolder the fittings, tighten the adapter, and resolder again - sounds like a pain.

Is there a better way to do this other than unions? I've thought about stainless / copper flexible hose, but it seems like there should be something more reliable and more permanent.

Comments

  • JohnNY
    JohnNY Member Posts: 3,287
    That's not the part that makes the seal. The inner ring seat does. I would use that union.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
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    TeratiniCanuckerethicalpaulIntplm.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,210
    That's not the part that makes the seal. The inner ring seat does. I would use that union.


    I agree - the union looks OK. In addition, I would add some pipe dope to the mating surfaces.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    TeratiniIntplm.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,564
    Hi, Another thought that might be of use is to put two turns of Teflon tape on the threads of the union so that it can be firmly tightened up... so leaking is less likely. By the way, I’ve had good luck with corrugated stainless flex lines. Just retighten after six months.

    Yours, Larry
    Teratini
  • mattmia2
    mattmia2 Member Posts: 10,755
    I would use brass between the copper and stainless. HTP requires it.
    Intplm.
  • Teratini
    Teratini Member Posts: 13
    @mattmia2 I thought the same originally, but a post said the Lochinvar manufacturer's rep said copper was ok.

    Also, the post below said HTP recommended copper or brass. Have they changed guidance since 2017?

    https://forum.heatinghelp.com/discussion/161919/any-issue-with-mixing-of-stainless-copper-brass-and-back-again
  • mattmia2
    mattmia2 Member Posts: 10,755
    It says use a brass fitting in the detailed instructions, then in a caution box it says use only copper or brass. Either is probably ok. Which is better probably depends on your exact water chemistry and the exact stainless alloy.
    Teratini
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,283
    I would use brass unions
    TeratiniBillyOSuperTech
  • Teratini
    Teratini Member Posts: 13
    Ordered the brass unions!
  • hot_rod
    hot_rod Member Posts: 23,108
    Or skip the unions altogether, what purpose will they serve unless an identical tank is someday replaced. Same with boilers😉
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2rick in AlaskaSolid_Fuel_ManIntplm.
  • mattmia2
    mattmia2 Member Posts: 10,755
    they cam in handy when i had an iron fitting that didn't seal on my boiler and i had to take it apart and add new tape and dope...
    Teratini
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,210
    edited September 2020
    Or skip the unions altogether, what purpose will they serve unless an identical tank is someday replaced. Same with boilers😉


    I put unions on everything: boilers, indirects, buffer tanks, expansion tanks, fill valves and hardly ever need to take them apart for whatever reason, maybe 5% of the time. But that 5% is a happy time that I put them there.

    Why do you think boiler manufacturers show them on piping schematics?

    I guess I'm always thinking about the next guy. I may not be around when he replaces that piece of equipment, but I can see the the smile on his face.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    SuperTech
  • Teratini
    Teratini Member Posts: 13
    hot_rod said:

    Or skip the unions altogether, what purpose will they serve unless an identical tank is someday replaced. Same with boilers😉

    Let's just say my soldering is less than inspiring....
  • hot_rod
    hot_rod Member Posts: 23,108
    Propress couplings work quickly for changing out equipment :)
    Alan (California Radiant) Forbes said:

    Or skip the unions altogether, what purpose will they serve unless an identical tank is someday replaced. Same with boilers😉


    I put unions on everything: boilers, indirects, buffer tanks, expansion tanks, fill valves and hardly ever need to take them apart for whatever reason, maybe 5% of the time. But that 5% is a happy time that I put them there.

    Why do you think boiler manufacturers show them on piping schematics?

    I guess I'm always thinking about the next guy. I may not be around when he replaces that piece of equipment, but I can see the the smile on his face.
    The next guy will probably be a ProPress or SharkGrip guy, or gal :)

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    bucksnort

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