I've not known of one (or a Southwind, for that matter) to be wired through, say, and oil pressure switch. They'd all fire up with just the master on, if that's what you wanted. This is on Seneca IIs, PA30s, and Aztecs (and one Jeep). Overall I found them very reliable.

Goodman now owns the Janitrol name; there's no mention of it on their website that I can find. Stewart-Warner still mentions combustion heaters; OP might contact them for a manual. The Southwind operated similarly to the Janitrol, IIRC.