My belief is that you can over winter very small colonies if you provide for the lack of heater bees with artificial heat and/or insulation. Next winter I’m going to try to winter mini mating nucs if I can solve my wax moth problems.
I really liked your heater tape solution. You’ve got a nice elegant design with a built in controller. A shut off temp of 50F is probably about ideal for a full sized hive. Some of the old books claim slightly warmer temps enhance survivability with the trade off of more stores consumed. At 50F though, you should not have to worry about wax moths.
I’m a little more insulated than you are. My hives have 2” EPS foam on all sides. Like you, I have no moisture problems whatsoever. Dry as a bone in there.
I was going to create a new post showing my latest batch of potted heaters and how I made them. Until I get around to doing that, here’s an earlier link talking about them and showing them before they are potted. http://forum.beemaster.com/index.php/topic,31071.0.html
I think I bought about 100 2watt power resistors for $1 in total. I pot them using a bag of mortar which makes about 30 10watt heaters. So for about $5, I have 30 heaters (10 watts each).
“Potting” is a term used to describe covering something with an insulating material, water proofing material, or thermal material, etc. In this case, I’m just sticking my raw power resistors (see the link) in cement molds and pouring mortar on top for the purpose of acting as a heat sink for the resistors. Without a heat sink of some sort, the resistors surface temps get to 180F and that could catch something on fire in the hive. When embedded in cement, the resistors still put out the same amount of heat, but the surface area is larger and dissipates more heat. The net result is a heater with a surface temp of about 100F instead of 180F and still putting out 10 watts of heat. Actually the surface temp is moderate enough that the dang wax moths often spin their cocoons right on the heaters!!!