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Suggested hydronic water treatment to preven corrosion

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The crud appears to be iron corrosion.

Comments

  • Charlie Taylor_2
    Charlie Taylor_2 Member Posts: 34
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    Suggested hydronic water treatment to preven corrosion

    My radiant heating system using Onix tubing has had some serious corrosion of the ferrous components. I have just cleaned out the crud and flushed the system. I never add water so the issue isn't make-up water.

    Can someone suggest a water treatment that can reduce future corrosion without cost $120/gallon like the Rhomar product. It is just for four loops to the manifold with around 35-feet x 2 for the connection to the water heater loop.

    The photos show a 1 year old circulator. The expansion tank totally failed, which I was unaware of until the Combicore was replaced last month. It was corroded as well.

    Thanks.
  • Big Ed_3
    Big Ed_3 Member Posts: 170
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    What Temperture .......

    .....are you running the system at ?
  • Charlie Taylor_2
    Charlie Taylor_2 Member Posts: 34
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    The system runs at 145* in the dead of winter. At 120* in the early winter. Hardwood floors with staple up.
  • In-floors

    Dirty little secret.
  • Paul B_5
    Paul B_5 Member Posts: 60
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    How about a Sidestream filter by heatlink or other manufacturers. What is that Crud???
  • Micro Bubbler

    Take it apart and look inside.
  • Charlie Taylor_2
    Charlie Taylor_2 Member Posts: 34
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    That's the only part that I didn't even think of opening up
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
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    Onix tubing

    Doesn't Onix tubing have an oxygen barrier? Or is there something wrong with Onix?

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • ttekushan_3
    ttekushan_3 Member Posts: 958
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    with satisfaction

    I've used 8-Way boiler water treatment. Made by Stewart/Hall, now Rectorseal.

    About $36 a gallon. One gallon should treat that system. Maybe even less.

    Follow the instructions. First treatment will liberate all sorts of crud; flush it out. Second treatment leave in there.

    Terry
    terry
  • hot_rod
    hot_rod Member Posts: 22,157
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    corrosion in a closed loop system usually

    is caused by one of four methods

    O2
    low ph
    galvanic
    microbiological

    O2 is most common from my experience. Low ph is generally seen in glycoled systems that have had the glycol overheated and abused.

    Galvanic could be an option as that old Combi did have an aluminum coil, and you have steel, copper, maybe brass? Usually it's galvanized(zinc) in the systems that show galvanic corrosion.

    With O2 corrosion first the O2 will react with unprotected iron to produce a black color , black ferrous hydroxide. This is often seen in the clear non barrier radiant systems as grey, then black water.

    With enough O2 or O2 ingress the color turns red (red ferric hydroxide. Some system just go black and stay there. The red or orange color indicates more advanced corrosion. This LOOKS like what you have going on.

    This was a very common sighting in the early PB and solar roll systems. Often to the point of plugging up tubes completely.

    In your case it presented as a stuck check :)

    Can't be 100% sure with a good analysis of your water. From my experience the O2 ingress with black or red water are most common.

    I've only seen one iron bacteria problem. You'll know it by the strong sewer smell to the water. Bacteria farts, actually to put it in laymen's terms :) Iron bacteria will turn a cast iron pump volute soft to the point it can be carved away with a pocket knife. Stinky, oily, nasty stuff. very hard to kill and clean out of a system.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Weezbo
    Weezbo Member Posts: 6,232
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    everyone wants you to find the correct answer...

    you must feel bombarded with all this info...

    see, there are a lot of things that are easy for someone to blow right by, plus there are things that realization has yet to catch up with "the New experience"*~/:)

    our trade is Fortunate that way, bored seldom enters the train of thought although Now What ? often does :)

    The thermal problem you have, i call Drift Theory,...soon as one catches the right Drift the mathematics is simple :)

    still got that white bucket? good thing to keep around ,so would a transfer pump and three washing machine hoses...
  • Charlie Taylor_2
    Charlie Taylor_2 Member Posts: 34
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    All of you guys are great. I really appreciate the help.

    The water was really black when I first drained water from the system. After the flushing, it is now just a very slight rust color.
  • hot_rod
    hot_rod Member Posts: 22,157
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    If it is a new Combi 2 heater

    they now have a steel coil inside. You may not need the more expensive treatment, as the Rhomar is blended to protect aluminum. That's a big reason the price is higher then other treatments.

    Read the Weil Ultra installation supplement and they require a 7-8.5 ph in the aluminum HX.. That's a tight spec. Probably tighter then most contractors can accuratly measure?

    There remains the question with Onix ... can the aluminum layer ever be exposed to the system fluid?? Perhaps a break in the inner tube? If so I highly recommend a conditioner that is aluminum friendly. I suspet aggressive water would go after that thin aluminum layer rather quickly.

    If I owned a system with aluminum components I would certainly purchase an electronic PH stick meter. Graingers and others have them for around 80 bucks. Very inexpensive insurance if you have ever seen the results of high or low ph on aluminum. Ask Slant Fin. They tested most of the so called AL friendly glycols against aluminum heat exchangers.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
This discussion has been closed.