Citradia, Yes, Very neat. I can see why your redesign for snow load was important. Im impressed at the dedication and all the testing and tinkering that goes along with it. Having temp regulated smaller cold frames in that climate is not easy especially stand alone as you are doing.. But the process inevitably leads to better more efficient set ups.
Ill bet you trudge out there on cold mornings to check on all of them!
I cold frame here in Pensacola as we get cold weather but nothing like that. I use Christmas lights, the old fashioned ones, and they keep my enclosures about 40-45 degrees. Stake flood lights with 150 watt halogens also work very well. Ive found that the trees though will grow larger and larger requiring bigger and bigger enclosures. Ive now got a 10 foot blood orange in an enclosure I rebuild every year. Im at the point where Im profecting faster expandable set ups as these cold frames are time intensive.
I noticed your using small desk heaters. Ive been looking for ones that are thermostatically controlled in the 300 watt range... Are you using the thermocubes to turn yours on and off? If so - how is that working for you?
I remotely monitor my enclosures with this-
Ambient Weather WS-21 Wireless 8-Channel Thermometer . Can have I think up to 8 different remote sensors. shows me high and low for each monitor.
Currently experimenting with an ibc water tote with an aquarium heater element suspended inside. water is preheated by the sun with an array of heliatos ez connect panels...
http://www.heliatos.com/