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Bosch Instantanious H/W system Probs

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  • Bosch Instantanious H/W system Probs

    I have had fantastic instantanious hot water from my system for the last couple of years and now all of a sudden my hot water is only luke warm at best. I can only have the water flowing at a dribble to get hot water. The system has no temperature dial. I have tried turning all the gas taps off and resetting it but that hasnt made any difference.

    Any Ideas??


  • #2
    Re: Bosch Instantanious H/W system Probs

    sounds like a smaller unit since there is no thermostat.

    a big problem with tankless heaters, high btu's, is liming of the heat exchanger.

    since a typical household tank 40-50 gallons is 32,000-40,000 btu's. a tankless is 119,000 - 190,000 btu's. this high heat through a heat exchanger and not the bottom of a storage tank, will cause liming inside of the copper tube water ways. this will slow the flow and cause overheating, thus shutting off the unit, due to overheating.

    try to flush out the heater with household white vinegar. a proper installation should have hot and cold shut off valves and bypass tees with valves installed on the manifold of the heater. circulate the vinegar, 1-2 gallons (4-8 liters) through the heater with a small pump inside of a plastic bucket. the bucket will catch the debris as you progress and keep it circulating for approx. 1/2 hour. make sure you flush out the vinegar prior to reconnecting to the house side of the hot outlet.

    this might fix your problem. this is also required on an annual basis to prevent liming and to not void your warranty with the manufacturer.

    if you still need help, my anniversary is coming up end of the month and mrs seat down has never been down under

    phoebe it is


    • #3
      Re: Bosch Instantanious H/W system Probs

      I have no idea of the unit,

      But most have a flow switch of some type to turn on the heater units (either gas or electric),

      Is the flow switch working?

      If the burners are functioning OK, and it is not heating, then the system that turns the burners on and off probably is not working,

      I would check out your manual that came with it, and see if there are any maintenance tips, if that doesn't work, you may need get a hold of a servicetec,

      I located this place and my be be able to down load your manual on line,

      it could also be in the electronic lighting system or the flame sensor,
      Last edited by BHD; 04-06-2007, 10:13 AM.
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