Ah, a wise man has wise ways (and saves money to boot). If it's worked for you for 3 yrs. I would call that a successful experiment. I've been running a two-stage controller on my cave with a 15W calendbra bulb for heating but have been on the lookout for a small wattage, inexpensive and non-breakable heater. I've heard from a couple of people who don't like the "glass" bulb and
this looks like a good alternative, and by the time you pay for the cordage, socket, and bulb the $ pretty much a wash. I would like to follow up with you later Sailor about any details as we've had inquires about if our controllers can be used for larger enclosures and this looks like a good DIY project for people who have or want to use a simple thermostat (Ranco, Johnson Controls or ours) instead of a Coolbot.
That said, I wouldn't personally use a CFL or any fluorescent for this application. First they are, well, efficient and what you need is heat, not efficiency. I think you would find a 7 watt incandescent (or the aquarium heater) would provide the same heat as a 40 watt or so CFL. Most important is if the thing breaks in an enclosed environment with exposed food
you really have a problem. It looks like you're using a guard that probably complies with OSHA regs., but there is typically around 3 to 5 mg of toxic mercury in the form of vapor that will be released and if it breaks in a cool environment the Hg could condense on cool surfaces. Hopefully LED lighting prices will keep coming down and CFL's will go the way of the ozone hole (oops, looks like the
ozone hole is as big as ever
!).