So I am paranoid and added three temp/humidity detectors in my Brinsea Ova one one each shelf. The temp. drops one full degree from the 1st to 3rd shelf! (Yes, I switched the detectors around and got the same temperature range.) That was empty, nothing to impede airflow. I'm becoming really unimpressed with this unit. I needed to put the eggs in so I chose the middle shelf (where I was calibrating previously). I suppose the first candling in a few days will tell.