I recently purchased a JC A419 thermostat and flexwatt tape (mgreptiles.com) for my cage (a modified storage container) and find it difficult to reach my desired ambient cage temp. There may be two or three possible reasons for this. First, my basement temp was in the low 50s today at noon, and drops into the 40s at night. Second, the modified storage container I use is opaque and considerably thicker than Rubbermaids and Sterlites. I fitted the "front" with a large plexiglass window. The main issue with the container is that it does not retain heat very well. With the thermostat's initial setting of 80 degrees F (and letting it run for 3-4 hours), my reading was in the upper 60s/low 70s -- with the probe touching the bottom of the cage. When the probe was placed 1 inch above the cage floor, the reading was in the low 60s. When I lift the cage, the bottom of the cage loses heat FAST. You can feel it cool in seconds. Third, my cage is on a heavy duty 5-shelf storage system and is totally exposed.
To "fix" my heating issue I checked my P4 jumpers based on what I understood in the manual. The thermostat P4 jumpers were set for heating mode and a CUTOUT at setpoint. I changed the P4 jumper to CUT-IN at the setpoint -- not changing the heating mode setting. I want the heat tape to shut off when the desired ambient temp (82 degrees F) is met, and cut back on when the temp drops a degree or so (80-81 degrees F). After more hours of waiting, I'm not sure if this "fixed" anything. Not being able to reach my ambient temp in a "normal" way makes it difficult for me to evaluate whether my cut-in change was the way to go. Any clarity would be greatly appreciated. 
I have since gradually changed my thermostat setting (still in "cut-in" setting) to 135 degrees F. This results in a cage floor temp of 85-87 degrees. The temp probe reads about 80 degrees 1" above the floor. I have an Amazon Tree Boa and Crested Geckos. The boa is likely to spend more time on the floor of the cage. Is it normal to run the setpoint so high to achieve the desired ambient/air temp? I don't want to burn my pets, but feel my back is against the wall. I placed a 60 watt lamp on top of the plastic hood (without mesh) and noticed that it started to sag. When it cooled, the top maintained its original flat shape. I don't want to cut out a fitting for a lamp in the hood since I am already having difficuty warming the inside for the cage.
Has anyone had problems with thicker/some plastics not holding/transferring heat? I imagine the thinner plastic used in Rubbermaids and Sterlites allow heat to "flow" through them better. What is the max. recommended flexwatt heat settings for Rubbermaids and Sterlites? Are Rubbermaid containers more durable than Sterlite's? Is glass a better material when flexwatt and thermostats are used?
I have a standard 3' long Neodesha cage from years ago. Is this my best option for the Amazon Tree Boa?
