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Interpreting Boiler Water Quality Test Results

D107D107 Member Posts: 1,724
edited June 2019 in Water Quality
Just got the results back from Rhomar for the water in my new boiler. Note that a Adey MC3 cleaner was in the old system for a few weeks before the install, then it was thoroughly flushed, then re-filled, then de-mineralized, then MC1 inhibitor was added. The system is old converted gravity in the early 80s. Two of three zones are CI rads, one zone all baseboard with copper piping. The old steel risers to main and 2nd floors are still there; 3/4" inch copper piping connects all the risers down in the basement in series--each floor separately.

See attached test results. PH of 7.01 is neutral--should be higher, less acidic. The level of inhibitors is way too low; the chemist believes that the inhibitors may have 'complexed' --joined--with the dissolved iron and sediments in solution rendering the inhibitors ineffective. The recommendation is to drain out and re-fill this water. I told him for the time being our intention is to add a Caleffi dirtmag filter to the common return (the existing Magnaclean only filters the heating return) and add some more MC1 as if there currently none in the system. Then wait until heating season and re-test. He agreed that would be ok.

What I have to find out from Adey is if MC1+ pushes towards acidity; if so perhaps another inhibitor should be used. The sample was taken from the bottom of the Turbomax tank--after a dhw cycle so the turbulence made the debris a bit less concentrated--but it's possible the sample was not truly representative of an average, but still in the ballpark. I wonder what the results would have been in the old system--I'm thinking sometimes all these cleaners etc stir up a lot of the old rust and corrosion. I'm all ears for anyone's opinions on this.


  • hot_rodhot_rod Member Posts: 14,420
    systems with proper hydronic glycols or conditioners run in the 9-10 ph range The manufacturer of the chemical you used should have data to indicate appropiate levels Also a test kit to use along with their product?

    In addition to the recommendations, make sure the fill or blend water is good quality, low hardness and TDS

    Good chemicals and bad water may not get the results you expect.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • D107D107 Member Posts: 1,724
    edited June 2019
    @hot_rod we have a caleffi demineralizing filter on the autofeed. And we'll test water annually. We don't use glycol.
  • ZmanZman Member Posts: 6,337
    Out of curiosity, how is the tap water?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • D107D107 Member Posts: 1,724
    @Zman makeup water is not so great either. See attached make-up water test from 2017. Not super-hard but...

  • hot_rodhot_rod Member Posts: 14,420
    The deminerlizer cartridge will do about 35 to 40 gallons, it is mainly for adding some water after filling, while purging What is the total system volume? You’ll want to pull that hardness and TDS down some before blending in inhibitors if possible
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • D107D107 Member Posts: 1,724
    Yes the caleffi unit is just for small water input. Installer used axiom puropal cartridges to treat after the fill before the inhibitors. We're guessing 75 gal total system which is 50 for turbomax, 5 boiler and 20 piping.

    So it seems we should test water after more demineralization is done, then inhibitors.

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