Quote Originally Posted by kitedemon View Post
Check the probe is plugged in and that it is in the right space for the rack outlet. I would also make sure the probe has not pulled free it sounds like it could be loose. Have you used aluminum tape to secure the probe? This can drop the probe response some as it is effected by ambient air temps. Have you checked the herpstats temp settings just to double check? Do you have a failsafe or have you set the low end temp to power off? What are the ambient air temps.

Racks often have variation middle top and bottom and flexwatt varies 5% typically spot to spot (5% at 100º is 5ºF) I like to run a max power test before any animals are around to a find out how bad a failure will be (how critical a failsafe is) and to find the hottest hot spot. It is also possible you have a cool area and just happened to place the probe there. Racks are always a compromise about getting the approximate temps they often vary some not as much as you have described but some.
Yes, my probe is secured with aluminum tape, what other method would you recommend? The ambient air is a bit cool in the room, usually about 72-75, never lower than 70. The rack's cool side hovers about 74 when I wake up in the morning, and goes up to 76-80 during the day. Yes, my fail safe is the herpstat, it has high and low temp alarms and will automatically shut off if it gets too hot.