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domestic hot water issue on 3rd floor

nytech28 Member Posts: 67
hello , I have customer saying he has no hot water in his faucets or kichen in his 3rd floor apt , I check the domestic hot water tank it fires up, pipe is hot but not getting hot water to apt, pressure seems to be good , seems like something going in the apt, any idea that can help fix this issue.


  • mattmia2
    mattmia2 Member Posts: 9,734
    Is there no water coming out of the hot valve or is the water coming out just not hot? How many fixtures did you try? What kind of faucets are they?
    Mad Dog_2
  • Zman
    Zman Member Posts: 7,572
    It sounds like a hot/cold cross connect. I used to see it a lot when a mop sink with a Wye hose attached had the hot and cold valves open and the mixed valve was closed. It usually effects a nearby unit with common plumbing.
    More often now I see it in aftermarket shower heads with shutoff on the head. People leave the valves on but shut off the head. This allows the hot and cold to mix , usually causing an issue in a nearby unit.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Mad Dog_2kcopp
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,095
    Where'd he go?  Mad Dog
  • nytech28
    nytech28 Member Posts: 67
    not sure what changed , but the tanent saying since he moved in , hes not getting hot water in his bathroom meaning his sink faucet/bathtub & kitchen, all units  gets hot for few seconds & then gets cold again,i.ll probably have to get plumber involved hvac techs dont get involved in that type of plumbing issues , I just wanted to help out.
  • hot_rod
    hot_rod Member Posts: 22,246
    Any single handle shower valves? They can cross when the cartridge goes bad.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,324
    Hi, From your description, I think Zman nailed it. Sounds like a crossover or cross connection. It’s easy to test for. Shut off cold supply to the water heater and open any hot tap. If it keeps running and turns cold after a while, you know cold is getting in.

    Yours, Larry
  • nytech28
    nytech28 Member Posts: 67
    it's a single handle shower head