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  1. #1
    Join Date
    Jun 2003
    Location
    Lenexa, KS
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    Question Recommended Minimum Flushing on Rinnai RUR98i

    Howdy, folks,

    I've had a Rinnai RUR98i for a little over two years now. I don't have particularly hard water.

    According to the Rinnai Service manual and IOM, the unit must be flushed "periodically." Beyond that, the manual states that a flushing procedure must be performed whenever there is a LC0-LC9 service code. I have never seen this service code and I have the controller mounted conspicuously so I see it every day.

    I'm not looking for more work to do, but I also don't want to neglect maintenance on the unit. If there is no code, is it good and I could just leave it alone, or is there some minimum flush that should occur to the unit, code or no code? Rinnai seems to offer little guidance beyond the error code. There are four adults living in the house so the unit gets its fair share of use.

    I did just clean the inlet strainer and it was pretty gunky. It's one of the reasons I ask.

    Thanks!
    "We are what we repeatedly do.
    Excellence, then, is not an act, but a habit."
    -Aristotle

  2. #2
    Join Date
    Dec 2009
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    maroon lazyboy
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    Flush it every year with Flo-Aide or whatever Rin recommends

  3. #3
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    What is the number of the hardness of your water?

  4. #4
    Join Date
    Dec 2013
    Location
    Grand Junction Colorado
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    209
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    Rinnai recommends flushing out once a year. But that is vague. Needs more if water hardness is more than 7 grains per gallon. Plus if your family is using it more than average.
    I recommend installing a scale blaster. It works great at binding the minerals together vs binding to Plumbing systems. It has been an industrial design for many years untill it has been commercialized to residential.
    It will significantly reduce mineral built up in the heat exchanger.

    Sent from my Pixel 2 XL using Tapatalk

  5. #5
    Join Date
    Jun 2003
    Location
    Lenexa, KS
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    487
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    Thread Starter
    Quote Originally Posted by HVAC_Marc View Post
    What is the number of the hardness of your water?
    8.36 GPG
    "We are what we repeatedly do.
    Excellence, then, is not an act, but a habit."
    -Aristotle

  6. #6
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
    Posts
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    Quote Originally Posted by gschra11 View Post
    8.36 GPG
    your water is on the upper end of moderately hard. based on that, you should flush and acid wash annually

  7. #7
    Join Date
    Jun 2003
    Location
    Lenexa, KS
    Posts
    487
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    Thread Starter
    Thank you all for your input. I'll buy my vinegar tonight.
    "We are what we repeatedly do.
    Excellence, then, is not an act, but a habit."
    -Aristotle

  8. #8
    Join Date
    Aug 2018
    Posts
    13
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    Vinegar is cheap and works just fine for getting rid of scale. If you go to costco you could get a flat of Coke for pretty cheap and have a nice surprise for your kids when they go get some hot water to drink

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