well i have a PE-1 temp gun and i check the temps at an inch above the middle of the spots i'm checking. like in the middle of the area directly above where the heat pad is. i also check the temp of the bare surface there cuz my girl pushes the bark away to sit on the bare surface so i wanna know exactly what she's sitting on.
if the temp readings i've been getting all along are higher then what i've thought then some of those warm side temps have been 100-102 but my girl does not have a burn so i think she's ok. when the temps i get reach 98+ i'll turn the thermostat down a tiny bit until the temp goes down to around 90-93.
i quit stressing that i wasnt getting exactly 90/80 and just settled for 85-90 warm/75-80 cool. but because i'm neuroticly monitoring temps and adjusting the thermostat to stay within those ranges it never dips below the lowest in those ranges.