Do the instructions actually indicate that it's position sensitive? I'm having a hard time understanding why it would matter if the control box was situated one way or another.
My thermostat model is the A19AAT (bought it from Northern Brewer).
This is what the instructions say:
"Mount the thermostat to a flat, vertical surface through the mounting holes in back of the case or hang the thermostat from a sturdy support using the beaded-chain hanger assembly"
Under importat it says:
"Mounting an A19AAT type thermostat on a rough or uneven surface may warp the control case and cause the thermostat to operate out of the intended temperature range. When mounting to rough or uneven surfaces, use only the top two mounting holes at the back of th thermostat. To avoid warping the thermostat case, do not over tighten the mounting screws"