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[E Yoder]

Wondering what you guys are seeing over time with break-down of propylene glycol in open systems like OWB's use. We use it rarely down here in the mid south so I'm not as experienced with picking up on when it's going bad. I've heard it can turn acidic.
Thanks for any info.

[wreckit87]

Not sure as far as acidity, but I know it will break down and lose potency as well as get "gummy". Think frog eggs, that green slimy crap you find in the lake. Sticks to everything and makes a nasty mess inside all the fittings and non-smooth runs in the system, and puts a gross slimy coating in the inside of the pipe. Probably not super detrimental to the system in that regard, but I feel like any slime is an obstruction and reduces system efficiency.

[E Yoder]

So when it breaks down do you flush with something to clean it? Any way to test or just eyeball it? What kind of time frame (I'm sure it varies).

[wreckit87]

I don't have anything factual unfortunately. But I did work on a system supposedly 6 years old with a 50% Propylene concentration when installed. Guy said he never boiled over or had to add water, and when I got ahold of it I just flushed it with well water for several hours and then circulated some TSP in it for 24 hours with the yuck settling in a barrel and flushed everything twice more to get it clean. When I drained the glycol out, it was hardly even slippery anymore and the barrels outside had ice on them before I was done with the new install. I'd guess it had about a 5% concentration left anymore, never measured it with a refractometer though. I'd sure never do it in my own system unless just short term

[E Yoder]

Thanks, I've seen a few systems that had glycol in them for a while and were plenty filthy. Just gathering info for when customers ask for it as it seems to be an ongoing maintenance/cost thing.

[NaturallyAspirated]

I'm pondering draining and flushing my system and going to a 100% water route, with some anti-corrode and perhaps biocide and maybe a UV sterilizer?  Anyone try one of those?  Any recommendations for flushing agents?  I want to basically reset the system that has been in use for some time...

[hoardac]

I have it on the inside of my house because of the concrete floors but not on the boiler side. Been ten years and no problems everything still looks good. I have it to 50 below burst protection.

[Sprinter]

I've never used it in an open system, always closed. Snow melt, garage/barns, lots of green houses. Never an issue with slime or debris. I use a test kit from cryotek , just dip strips. On government/municipal jobs we have to send it out to a lab.  Non ferrous systems have a ethylene glycol longer life. Cryotek is the brand most popular here.   You also have to account the heat transfer difference from straight water versus glycol , as it is 10-15% less depending on mix, plus it also has more head. Meaning the pump sized for water only will move less volume with glycol.  Manufacturers are happy to help with tech info....and testing.