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does anyone know what if any system effect it has if ethelyne glycol gets added to a system filled with propylene glycol? say for example an existing loop has propylene glycol and a unit gets added or branch piping gets relocated and ethelyne glycol gets added.


  • hot_rod
    hot_rod Member Posts: 22,348

    the toxicity of the PG a bit. Also the color:)

    They do blend together, EG is a slightly better transfer fluid and is common in larger commercial systems as a heat transfer fluid. EG is best kept away from potable water with double walled HX protection. PG may or may not require double walled HX, depends on your AHJ.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • AL_29
    AL_29 Member Posts: 44
    Are you sure they blend

    I have had some dealings with glycol in a geothermal closed loop system. I took several samples and they were different colors and mesured diferent freeze points. The major issues this customer was having was freezing water to water units. I sent all the samples to some company in Pensylvania and the one sample I had had a very high PH and lots of floating particles. I was told that different manufactures and different kinds of glycol will not mix and can cause corrosion and other adverse affects. Not sure who to believe.

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