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instantaneous hot water vs indirect water heater

I'm la little leery of instantaneous wall hung water heaters. i think there might be a problem with heat exchangers and condensation. how do they hold up over time?
seems like indirect water heaters are virtually trouble free.


  • Jamie Hall
    Jamie Hall Member Posts: 23,287
    They hold up OK, at least the good ones do. OK being perhaps 10 years, with decent water quality.

    The problem isn't so much in longevity, it's in that they have a very definite upper limit as to how much hot water flow they can produce. If that's adequate, OK.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 15,525

    Some people love instantaneous some hate them. I have never heard of anyone that didn't like their indirect.
  • hot_rod
    hot_rod Member Posts: 22,143
    Plenty of indirects fail before 10 years. Buy a quality brand with “real” warranty 
    On  stainless indirects be aware of the water spec listed with the tank, that can be a warranty decline issue, chlorides are of particular concern with stainless tanks 

    local suppliers generally know which brands last in the area the sell to.

    properly maintained a tank or tankless should last 15 years.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,293
    If you go the indirect route, a thought is to go with a glass-lined tank and change anodes regularly, which is normally every three to five years. I'm a fan of simple and indirects are far simpler than tankless heaters.

    Yours, Larry