"It's powered by it's own 24v transformer, something like a half amp draw. It stays on even when the furnace is off."
Hum... That might work really well in my home, then, as my air handler is virtually never off. I have the fan set to recirculate. The only time I turn it off is when I'm either changing the filter or when I'm heading out for an extended vacation.
How long does the bulb last?