glycol

dixontaxpreparer

We put in a system in 1993. It was pretty big, twelve zones, and part of the main (direct return) loops ran through an unheated space, so we charged the system with antifreeze. A couple of years later we moved the circulator to the supply side of the boiler after the expansion tank, and added some makeup glycol, but otherwise the system has been left alone.
Two months ago the highvent on top of the airscoop started spouting water. When I took the went apart, the guts seemed gone, so I think the glycol may be corrosive.
What do you think? Is the glycol corrosive? If so, what should we do? Thank you

Ken_40

Glycol is EXTREMELY

corrosive - after the inhibitors die off.

Clean the system with clean water, then with TSP (about 8 oz/100,000 of boiler size) and run it to 160+ for 5 minutes, getting each zone (one by one) to be cleaned, then, rinse each zone one by one - then put a fresh charge of glycol back in and check the pH annually.

When the pH goes below 6.5, repeat what is described above again. Given the natural trace amount of TSP that may be left behind (which is an alkaline pH [~8.0]) and also given the initial glycol installer probably did NOT properly clean the entire system of flux, oils, metal chips, etc., you should be good for many years.

Annual testing however is mandatory to prevent this from recurring. God knows what the rest of the system looks like! Hopefully, not like the vent you found gutless...

Assuming the system has no leaks, the TSP cleaning and fresh glycol should stop further corrosion in its tracks.

Let us know how you make out.

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Drew_2

Glycol

Ken's advice is right on target.
If you would like to talk about how to take care of antifreeze in a system, call me.

Drew
Noble Company
Noburst Antifreeze
800-678-6625/Ext. 108