There are better planned pump boxes that other members have put together. Hopefully they will post some pics for you, but here's my pump out- house...

[Linked Image]

The exhaust for the fan is the little rectangular screened opening at the top front. The fan is inside that opening blowing outward sucking air across the pump. I don't think it makes much difference if the fan is pushing air out or pulling it in from a cooling point of view, but I did not want to suck rain water in so I mounted it blowing out.

Here is the inside...

[Linked Image]

There is a long screened slot under the pump shelf that allows the air to be drawn in and across the motor. The pump is behind the white panel directly behind the drop light and the pump house has a false ceiling it that the fan lives in. So, it pulls air from the open area inside the house up through the enclosed pump shelf cabinet and through the false ceiling and out the top front. Rule of thumb...make the opening in the box opposite the fan twice the size of the fan cross sectional area. This applies wether you are pushing or pulling the air.

The only thing missing in the plumbing is the dump valve that I added by the pop-off valve.