Quote Originally Posted by brutal View Post
Drain, blow out with 40-50 PSI air and introduce RV antifreeze...and blow again while working any valves, faucets, etc. Antifreeze in the p-traps too.

Even a blown out system can retain moisture in the valves and freeze.

15 years without an incident doing it that way. Maybe it's overkill, maybe not?
I’ll take that advice.