glycol versus car antifreeze

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steveforg

New Member
Hearth Supporter
I know ones toxic and ones not but is there any other reason not to use car antifreeze? I ve got a 4000 sq ft house w/4 zones and am installing a memco 100 wood boiler outside. It would be nice to save a couple of bucks if there's no difference in the antifreeze
 
I think from a performance viewpoint car antifreeze would work fine. however, it's not allowed because it is toxic. If you're counting on 1/16" of metal to keep it out of your drinking water, I'd be concerned. A very small leak could be a very large problem.

In my case, I'd consider using it in my solar panels. They're unpressurized, and they exchange heat with an unpressurized storage tank which then transfers heat to my pressurized potable water. It would take two leaks and a violation of the laws of physics to get contamination from my solar panels to my potable water.

Using it in a pressurized system that's directly connected to potable water is a different situation.
 
Just to be clear, ETHYLENE GLYCOL is the toxic variety used in automotive (and other) applications.

PROPYLENE GLYCOL is the non-toxic variety used in RV water systems for winter storage (and other) applications.

They are both forms of GLYCOL, so make sure you get the stuff you want.
 
Do not use auto antifreeze in a hydronic system. You're asking for problems down the road with corrosion due to a different additive package in the two. Boiler antifreeze is a completely different animal. This is a classic case of "It's what you don't know that will kill you".

Aside from the the safety aspect, every boiler antifreeze manufacturer that I know of, Noble, Hercules, Rhomar etc, also includes special additives in their product to help with sludge buildup, oxygen scavenging and corrosion protection. There are different types that should be used based on what materials are in your system also.
 
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