Instant Hot Water Dispenser Problem

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Kiko, Feb 6, 2011.

  1. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    I have an Insinkerator instant hot water dispenser model SST-FLTR 2/3 Gallon. Lately, the water it dispenses is spitting and sputtering, as if air is getting into the system somehow. It happens randomly and is not related to the aerator. Any ideas of how air is getting into the system? There doesn't seem to be any leaks under the sink.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,631
    Location:
    Cave Creek, Arizona
    Usually that means the water is getting too hot and is turning to steam.
  3. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    I turned down the thermostat and ran out all the hot water in the tank. It still spits and sputters, even with cold water, so air must be getting in somewhere. Are there any seals in the tank that could be tightened up?
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,631
    Location:
    Cave Creek, Arizona
    Air does NOT get into that unit. It is NOT under any pressure so there are no "seals" to tighten. When you "open" the faucet handle you send water into the tank and that forces water out of the tank and out of the spout. The only way air could get INTO the tank is if some water leaked out , or boiled away, so there was a space for air to take its place.
  5. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    I just talked to a service tech at Insinkerator. He said there is an in internal aspiration valve in the tank that could have gone bad, and since it is not fixable, he will send me out a new tank.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,006
    Location:
    New England
    If I was going to guess, that valve is there to let air out so that the tank can fill with water. This is necessary to ensure the heating element is covered with water and doesn't burn up. The valve would close when the tank was at it's design fill height. If it leaked, you'd get water out. Once the tank is full the first time, it may never open again, as the incoming water pushes the stored hot out. It sounds to me that the thermostat is bad, and the water is hotter than design. Then, when you open the valve, because the pressure is off, it flashes to steam on the way out.
  7. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    I mentioned that the water sputters even after all the hot water is gone and only cold water is coming out. I don't see how there could be any steam getting through. Even if a fraction of the water "flashes to steam," it would surely condense back to liquid with all that cold water around it. Anyway, a new tank should fix the problem, unless air is getting in via one of the lines.
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