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Glycol failure

Simply Rad
Simply Rad Member Posts: 195
in Solar

hello all

I took on a service project on a solar thermal system which was installed 12 yrs ago. The owner said that last fall his neighbor saw steam coming off the solar array.
So, yesterday we tried to flush and refill the system with new glycol and found a clog. We were able to isolate the blockage to the collectors. The culprit was the glycol, which had crystallized and fully blocked the 2 panel array.
I have never seen glycol react like this and I am assuming from stagnation from the system being low on fluid.

IMG_2433.jpeg

And second, how can we unplug the panels. We tried air and water, and had little progress. The picture is a small sample of the blockage material.
thanks
Jeffrey.

Jeffrey Campbell
Mad Dog_2

Comments

  • Mad Dog_2
    Mad Dog_2 Member Posts: 8,167

    Yes...not good. What does the piping & storage tank set up look like? Mad Dog

    Consulting by Mad Dog & Matt Jr.
  • Mad Dog_2
    Mad Dog_2 Member Posts: 8,167

    That may be very tough to clear. How hard is it? Mad Dog

    Consulting by Mad Dog & Matt Jr.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,848

    Hi, If the collectors are the normal header and tube style, you could use a rod or smaller pipe to clear the headers. Then hook up water so you can pressurize from one side, and then the other side. This back and forth approach has worked for me in clearing solids from plumbing.
    Yours, Larry

    Mad Dog_2
  • hot_rod
    hot_rod Member Posts: 25,107

    i have never seen that before! I wonder if someone added stop leak at one point?

    If you get any flow at all, maybe an acid cleaner.

    We here is the blockage? Are they serpentine or ladder style absorbers ?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Mad Dog_2
  • Simply Rad
    Simply Rad Member Posts: 195

    gentlemen thanks for reply’s

    The system is a Caleffi package…panels, dual coil indirect and Paw pump station with Caleffi control. We used pressured air and water to try to dislodge the blockage but it only seems to move to the next blockage spot. Even if we can get some flow through the panels I know the 1/4” or 5/16” risers will not all be cleared.
    HR you are pictured in the manual. The collectors are ladder style. Definitely no stop leak in the system. I am wondering if traditional glycol was used and not solar rated glycol. The bonded material is crystal like and kind out flaky.
    It all started when the Caleffi solar auto vent failed, the cap was left opened and the steam released through the open auto vent. It the lost fluid and stagnated for who knows how long.
    thanks for input.
    Jeffrey

    Jeffrey Campbell
  • mattmia2
    mattmia2 Member Posts: 12,779

    did the fluid degrade and make that with the metals in the system because the inhibiters weren't maintained?

    Mad Dog_2
  • Grallert
    Grallert Member Posts: 965

    You might want to try vacuum. injecting water a little at a time while a strong vacuum is running. Maybe a dilute acid in the water. But I'd start with straight water and vacuum.

    Miss Hall's School service mechanic, greenhouse manager, teacher, dog walker and designated driver

    Mad Dog_2kcopp
  • hot_rod
    hot_rod Member Posts: 25,107

    glycol degrades quickly when the systems are underused. If they stagnate every day due to lack of dhw use, glycol may not last a year

    Automotive glycol has silicates, a salt that contains silicone and O2 molecules. I have seen that sludge car radiators.
    It could be that automotive EG was put in at some point?

    The risers are 1/2” in those panels , no aluminum in those system that could decompose. If you get flow, a cleaner should dissolve the sludge

    The Caleffi glycol was a bio, corn based PG product. It has a higher operating temperature than oil based, easier to pump, lower viscosity also.

    Those panels were built by Solar Skies.

    Solar Skies licensed the panel design from AET

    AET will build an exact replacement, if you tell them which size and what connections

    They were 6-1/2, 8, or 10’ by 4’ wide

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Mad Dog_2mattmia2

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