I've made this cage out of 3/4 melamine, each large unit measures roughly 2' X 4' X 11" and the top two smaller units are roughly 2' X 2' X 11". I am planning to use the Ultratherms to heat each unit (the 11" X 23" {27.25 Watts} for the large cages, the 6" X 17" {9.0 Watts} for the small ones). I mounted the heat pads on the wall of one end (as recommended in the enclosed literature) of the large units (haven't received the pads for the small units yet as that was a last minute design change). Per the literature, it is not necessary to use a thermostat for the heat pads (they're essentially very thick low wattage flexwatt, but seem MUCH better made - came highly recommended by an online friend). They've been plugged in for at least a couple of hours now, possibly more. The bottom most unit is reading 92-94F on the hot end and 80-82F on the low end, the next two middle units are registering right at or just below 100F on the warm end and about 82-85F on the cool ends, even without heat sources the right hand small unit (on the same side as the current heat pads) is reading 82-85F on the warm side and just below that on the cool end, the left hand unit (furthest from the heat sources) is about 80F regardless of thermometer location (no temp gun at this point, this is with a basic thermometer - though not the mercury type). The pads are warm to the touch, but not hot - you can comfortably leave your hand in place for as long as you like. I am debating attaching my Helix thermostat since they really don't seem to overheat. If I do, I was thinking of only connecting the two units that currently have warm ends at 98-100F and leaving the bottom unit free (which is probably being effected by the air conditioning coming through the floor vents). What I do with the top two units will depend on their temperature ranges when I install the heat pads in them.
What are your opinions on this? Has anyone used the Ultratherm heat panels/pads? Was a thermostat necessary?
Your input is greatly appreciated. 
Raven
