Incubator question. Shelves/Fan

So I'm just about to plug in my incubator except I need to plug in the fan.

My question is this - I have glass shelves in the incubator, but there is an inch gap between the back and the front of the shelves for airflow.

Should I put the fan on the bottom facing towards the back to blow the hot air upwards, or since heat rises should i put the fan on the top to blow the hot air back downwards?

Also, is glass an acceptable shelf medium, or should I switch the shelves to wire or something?

The glass should be fine as long as there is enough room for airflow around them.
I have my fan at the top of my incubator facing downwards and it works great for keeping the entire incubator pretty even as far as temps go. I only have about 1/2 degree difference between the top and bottom shelves.


Gavin

We have our fan on the bottom blowing up through wire shelves and it holds within 1/2 a degree top to bottom.
I think the main concern is airflow.

i have one aiming down and on the other side i have one aiming up

The best thing to do is plug it in and run it. Glass will restrict the air flow, but that doesn't mean it won't work. you have to run it and have a couple thermometers to see the difference in temps from top to bottom, air flow is most important in helping reduce the temp difference. you might have to change things around a few times to get the best conditions. it took me about four changes with fan placing and cutting off some of the heat tape to get it where I wanted it. remember your incubator controls your temps. your egg box controls your humidity. good luck don