How different is the viscosity of EG from PG at -30F? More importantly, does
it matter? We are only pumping when there is heat to be collected. I've
always used PG (propylene not polyethylene BTW) in the antifreezed systems I've
done, but most of what I've done is freeze-proof thermosyphon or drainback, so
i don't have much experience with antifreeze.
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