I have a couple PVC CB-70 racks stacked 8 high which are basically identical to RBI's racks. I have my Herpstat set to 93.5 degrees on the 5th (from the top) shelf and my temperatures read 93-97 degrees. The room is about 70-75 degrees.

Only one tub gets up to 97 degrees. Don't know how, but she seems fine with that temperature right now.

Ive always had my hot spots hotter then what my Herpstat is set to. Why? I don't know. You'd think it'd be cooler but it's not (for me anyway).

I am still trying to fiddle with it but I never seem to get it perfect. It's either too cool or too warm.

Good luck.