Okay so I've been testing for a few hours now after sealing up the gap I had in mine. This is a test for a BD.
5cm desert sand substrate on top of the heat cover and leveled off surrounding.
I've been taking half hourly readings with an IR laser thermometer, in the 4 corners of the cover and 2 central (to see if the even heat spread is true). In the results below, the figures match to the diagram below (done on paint, it's a masterpiece, don't diss.) in order, so point 1 being the first number, 2 being the second and so on.
I have a 100w prorep day heat bulb in the hot end, and a prorep 75w day heat bulb in the cool end, then the test pieces centre. All thermostats placed on the substrate to get best reading.
Here's the figures in deg celcius that I've been aiming for:
30 deg mid viv surface temp, basking end is at a constant 40 +/- 1, cool end 25 +/- 1
And here's the results thus far (temps taken on top of substrate) :
12:00 - 24 all over (this is when it first went in so room temp, it's my rep room so naturally warm)
12:30 - 26.7 - 26.8 - 26.8 - 26.9 - 28.1 - 28.2 (so reasonably consistent and starting to heat the substrate with effect)
13:00 - 29.8 - 29.9 - 29.8 - 29.7 - 30.3 - 30.4 (hitting the temperatures and reasonably even +/- a degree... Impressive so far)
13:30 - 30.3 - 30.2 - 29.8 - 29.9 - 31.1 - 30.9 (the fluctuation from left to right is obviously due to the hot/cold gradient which is expected so I'm pleased with this after 1.5hrs, as for the centre I'm guessing the time it takes the heat to get though the glass and substrate into the thermostat is the reason it's going above the temp I've set it to)
14:00 - 30.2 - 30.2 - 29.9 - 30.0 - 30.9 - 31.00 (I may as well stop here because since then it's been pretty much the same temps +/- 0.1 degree)
I'll be honest, it's an extremely simple design for protecting the mats from wear and tear, but at the same time it's simply effective. It's now 17:00 and the temps have been within that 0.1 gradient all over the sand substrate, if I notice any drastic changes I'll update again, I'm going to leave this running for a week and then do their survey as requested, however as it stands *touch wood* it looks like it does the job intended!
Just a side note, the back of the heat cover was flush against the back of the viv so no heat could escape, I did have to put some little stoppers (purple) aside each of the front corners to hold it in place though due the edges not being flush with the bottom (see diagram below), so the tape was basically rendered useless (green). As with larger reptiles I can imagine a lot of shuffling around being done and in turn this would disrupt the heat cover, so either the edge design needs a rethink or the stoppers should be included.