IIRC, one of the earlier threads shows how a $1 thermal-cutoff-switch could be attached to the smoke unit. When it gets too hot, power cuts off. When it cools down - probably taking several minutes - it starts up again. Lather, rinse, repeat. So you get both thermal protection and cycling behavior. Here's a photo of these simple 2-wire devices I recently posted for a discussion on protecting against an overheating solenoid in a crossing-gate mechanism. You choose the temperature where you want it to cut off.
