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ill effects of glycol

pat_3 Member Posts: 89
could someone tell me the basic ill effects of glycol in a heating system that is not properly maintained?thank you in advance


  • tls_9
    tls_9 Member Posts: 89

    Glycol can turn acidic with time. the Ph should be checked and adjusted at least once per year. It will attack the steel parts of your system. This can cause leaks. this often results in a thick sludge laying in low spots or plugging strainers valves etc. I also suspect glycol as the culprit in ruined impellers in many cases. Dont forget, dry glycol is will burn. A real hazzard when a boiler is dripping or piping repairs being made.

  • Plumdog
    Plumdog Member Posts: 18

    I think there are a lot of negatives to use of glycol in hydronic heating systems, not the least of which is that it makes your circulating fluid more viscous (thick, like molasses) and shortens life expectancy for pumps. It also seems to attack plastic and rubber packings, etc causing leaks. IMHO it is better to eliminate the cause of the freeze-ups by using extra care in insulating trouble spots, and let the system flow freely. JMIA
  • hr
    hr Member Posts: 6,106

    the glycol goes bad if the inhibitor package gets used up and not replaced. this could be caused by bad water or a ingress of O2 (non barrier pipe).

    The other common reason is overheating. depending on the brand somewhere around 350°F glycol gets stressed and can turn acidic. This issue is common with solar collectors that go stagnant. I've also seen this happen in boilers when the circ pumps fail and the fluid gets overheated.

    Keep the chemistry correct and glycol can last 10 years or more.

    Really glycol should be inhibited according to the amount of blend water YOU are mixing. The more fresh water, the higher the inhibitor package required, as the O2 inhibitor is in the glycol for the water not the glycol, same with the hardness inhibitors.

    I also highly recommend buying the good quality name brands. You will find they have better inhibitor packages. I think this is a case of where you get what you pay for.

    I have had good luck, and excellent support, from Dow, Nobel, and Hercules along these lines

    Stay away from RV and other glycols that are not inhibited for hydronic use.

    hot rod

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