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Radiant in-floor - Sludge, full reservior, glycol

Taurk Member Posts: 1

I have a radiant in-floor heating system that we installed when the house was built new 6 years ago. I noticed water coming out of the vent pipe coming off the boiler and when I started looking to cause, I found a lot of sludge building up in the vent trap. Upon further investigation, the reservoir that holds the glycol is FULL; it wasn't 6 months ago during the summer months.

The system is still keeping my basement and garage at temperature, but I'm quite concerned with these symptoms. Any ideas on what would cause the reservoir to fill up? Sludge? Related?

Thank you in advance for thoughts and ideas.


  • Jamie Hall
    Jamie Hall Member Posts: 17,011
    Reservoir? Vent pipe? Vent trap? eh?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SuperTech
    SuperTech Member Posts: 1,687
    Reservoir for glycol? Do you happen to know the model of the boiler? Pictures would be helpful. 
  • Zman
    Zman Member Posts: 6,958
    Some pictures would help. I have seen setups where they pipe the relief valve back into the glycol pig. That would explain your symptoms.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 15,004
    A few things that cause glycol to go bad or sludge, overheating on a regular basis, and exposure to air, oxygen really.
    Non barrier tubing of any type can ruin glycol quickly.

    Glycol really needs to be kept in a sealed air tight container to prevent the inhibitors from breaking down.

    One last think is putting glycol in a dirty system causes it to deteriorate quickly also.

    If all three of these condition exist, glycol can turn on you in a few months time. A yearly ph test will let you know when it is going south.
    Some pics would help
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream