Radiant heat panel probe placement

[Homebody]

Where do you all place your probe for your RHP? I’ve got a 90w pro products panel in 4x2x2ft pvc enclosure. I’m struggling with ambient temperatures which has been quite frustrating. My ambients are only 84-88 on the hot side, they fluctuate based on my house temperature. I checked surface temperatures with a heat gun and they seemed good 88-91 or so on the hot side. My concern is that the RHP is running at 100% power 24/7 trying to maintain the ambient temperature at 88, I’m afraid this will shorten the life of my RHP. Do you all recommend moving the probe or should I not worry? My probe is currently threaded through a hole in the back panel under the RHP approximately 10-12 inches from the substrate.

I have an 80 watt VE RHP and I put the probe 2-3" below the panel in accordance with the instructions. RHPs use infrared that heats objects better than the air. They make a nice hot spot, but they're not very good at raising ambient temperatures. See Reptile Basics's VE Radiant Heat Panel FAQ.