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Thread: Any Rinnai experts out there?

  1. #1
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,829

    Any Rinnai experts out there?

    We use three Rinnai C199s to heat our HLT, mostly by recirculating the castback water through them, but also for directly heating make-up water when we run low. Ours have now decided that they like heating hot water, but not cold. When fed on 50F city water, the flame will come on, then go out. The flow throttles all over the place when this is happening.

    The units do not give an error code when this happens, and they work fine when heating our 160F castback cooling water to 185F.

    I clean these every two weeks with a 2.5 pH solution of inhibited sulfomic acid, so they should be nice and clean.

    I've spoken to our Rinnai rep, but he seems as puzzled as me. The units are a little over 1 year old.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  2. #2
    Join Date
    Nov 2009
    Location
    Moab, Utah
    Posts
    500

    Considerations....

    Quote Originally Posted by TGTimm View Post
    We use three Rinnai C199s to heat our HLT, mostly by recirculating the castback water through them, but also for directly heating make-up water when we run low. Ours have now decided that they like heating hot water, but not cold. When fed on 50F city water, the flame will come on, then go out. The flow throttles all over the place when this is happening.

    The units do not give an error code when this happens, and they work fine when heating our 160F castback cooling water to 185F.

    I clean these every two weeks with a 2.5 pH solution of inhibited sulfomic acid, so they should be nice and clean.

    I've spoken to our Rinnai rep, but he seems as puzzled as me. The units are a little over 1 year old.
    Timm, its Standard for the phone lines for Tech support at these outfits to be totally jammed up. Thats how quirky and unstable this type of product is, and also standard for them to be mystified when they do things that supposedly have never been seen. With that said we are here dealing with a different brand, but there may be some things that count across the board.
    The inhibited sulfamic is absolutely the correct thing to clean with. Several of the commercial solutions sold for the Plumbing market will not remove scale " at all."
    I have made the following observations about sensitivities in these units.
    Incoming line pressure needs to be pretty consistent. If you are pump fed, I would think you are good on that front.
    The On Board inlet strainers, if present have to be totally clean. Due to the way they are designed in our case, it would be better to fit a larger WYE strainer ahead and remove them altogether. This would be more effective, less prone to failure, and easier to clean.
    Takagi recommends a cleaning cycle time of Minimum 1 hour. I have found 1.25 to 1.5 HR. to be even better, and I know your water is far worse than ours.
    Because your system has taken this characteristic on over time, my suggestion would be to start that they may not be clean and clear enough after De-Scale.
    I was working with a water cooled condenser on a VOGT Tube Ice Machine years ago and attempting to use KMP liquid descaler which was not ideal for the job.
    It would give a strong reaction and then leave quite a bit of scale behind which we finally got broke loose with compressed air and other types of force back and forth.
    It sounds like the firing rate does not modulate upward when it is needed under cold inlet conditions because the rest of the control logic is " conflicted " about what to do.
    With the Takagi remote, its possible to read a page worth of parameters that can then be submitted to Tech Support. When and if certain things are out of range some conclusions can be made, but typically they will tell you " We cannot find a reason for it to be doing this." So as I have been saying for years now to a mostly uninterested audience. These things are time wasters Supreme and will always keep you running when you have far better things to do.
    The most major factor of my analyses has been HX's that are not clean enough for the next FEW DAYS of run time with all other things being as they always were.
    People that do not have any responsibility or experience as Facilities Mechanics " think " tankless units are somehow great!
    This is a delusion.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    " No Cell Phone Zone."

  3. #3
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,829
    I agree 100% about the uselessness of these things. I was against them in the beginning, and now absolutely hate them. I waste more time keeping these damned things limping along than any other singe piece of kit in the brewery.

    I clean every two weeks, typically for several hours. I monitor the pH, and when it gets above 3.5, add more sulfomic acid to bring it back to 2.5. When the pH stabilizes, I call it good.

    Usually, if the units start to scale up I'll get a code or two, indicating an over-heating HX. No codes this time.

    Tankless water heaters are a scam. For those who worry about wasting energy by keeping a tank full of hot water, consider where that "waste" heat goes. My home heater is in the house, so any "waste" heat heats the house. We get about a month each year when this isn't a good thing--the rest of the time (like last night), we still need to heat the house--no waste at all.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

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