Originally Posted by mitchgo
A station master would work and be the cheapest
That's my vote too. Just keep some extra 9 volts with you just in case.
I use the controller maybe 5%-10% of the time on blow outs. Usually I open at the valves with the bleeder or solenoid, but we also manifold and rarely see scattered separate valves. As someone else said, maybe just drain the systems and go back when there is power. I've done that as well when we get a cold front coming in and can't get to all the blow outs. Then we go back at our leisure. At least you make the systems safe from freezing, and keep the customer happy. I can drain down more 2x-3x more systems in a day, than if I were to blow them out. Not as profitable, but when a storm like this comes in, ya gotta do, what ya gotta do.