I made an incubator out of a toybox, worked ok but I want to revise it. Does the heat source have to be above the eggs or can it be on the side??? now this incubtor is much longer than it is wide. Has a large computer fan on one side and its fairly deep. I've been using flexwatt heat tape which worked barely but I only used 1 foot, i'm going to change it to 2 feet. but, I had the heat tape on the back of the box and was wondering if I should move it to the lid so it radiates down rather that from the back to the front, but I like it on the back. What do you guys think?