------------------snipped-----------------------
I took a look, and saw no mention of ballasts rated for low temperatures
having heaters. It is the bulbs rather than the ballasts that are
impaired by low temperatures.

- Don Klipstein )

All you have to do is check the amp/watt draw of standard ballast and of one
that is rated for zero degrees. Since they light the same lamp the
difference is the heater.

Heater may be an over simplification.