Incubator fan decision

I'm planning on making an incubator out of this freezer

http://img693.imageshack.us/img693/4843/freezere.jpg

http://img6.imageshack.us/img6/3725/openfreezer.jpg

I'm going to completely gut it and put in some of those wire closet shelves and brackets so I can squeeze as much space out of it as possible. Not that I need that much space right now, but I only want to do this once.

I ordered 5 feet of 11" flexwatt and a Herpstat. Both arrived today. I would like to get to the gutting and building process, but I have to figure out what fan or fans I'm going to install and how. Here are my options.

First I have two 5" muffin fans. They are both 115V fans, so just a standard extension cord will work with these. The one on the right is 13W and the one on the left is 20W. I was thinking about putting them both on the ceiling on opposite sides pointing downward. This is my easiest option.

http://img96.imageshack.us/img96/3845/5inchmuffins.jpg

Next, I have several microwave oven fans. These are 120V also (standard extension cord). Not sure how I would mount them or where. I actually have about 7 or 8 of these laying around.

http://img717.imageshack.us/img717/8...rowavefans.jpg

http://img6.imageshack.us/img6/4882/microwavefan.jpg

Lastly, I have a dual squirrel cage blower fan from an over the range microwave. Its also 120V so again, just a standard extension cord will work. It is a dual speed fan, so I could just wire it up to run on the low setting.

http://img705.imageshack.us/img705/6480/squirrel1.jpg

For scale,

http://img13.imageshack.us/img13/9936/squirrell.jpg

I was thinking this would work if I put it on the ceiling in the back, blowing down across the flexwatt that will be running from top to bottom down the back wall of the freezer.

http://img85.imageshack.us/img85/498...lplacement.jpg

I'm leaning towards the squirrel cage blower, but I'm sure this is overkill. Is there any reason that I shouldn't use it?

If you could use any of these options what would you go with and why?

Personally I would do the 2 muffin fans. But instead on both pointing down I would do one on the bottom pointing up and on the opposite side one on the top pointing down so that you can get the air to circulate. I would be worried about using the fans with no shroud just for safety. but thats just me

have a similaer mircowave fan (somewere from my RC racing days) it was great for cooling a charger and some batteries if they got warm. I found it they themselves get warm and hot if ran long time. plus youneed to be carefully on setting them up as they can really bounce around whe nthey start up My was more like the blower type than the fan. ( maybe I will dig mine out and use it lol since it stored somewere in the trailer .)

I would second the vote for the muffin fans, and putting one on top and one on the bottom. All you want to do is keep the air moving, you don't want to move it too much or you'll dry your incubator out.

In a freezer unit like this, do you have to have a fan? Sorry, new at this and will need to be making one of these in the future, didn't see a fan mentioned in a write up on another freezer design. Thanks.

You do ned at least one fan in a frezer (or any incubator for that matter), as without a fan, you wil get some striation in the freezer (i.e. warmer air high, and coler air low). As other have stated, I would use the first option. The microwave oven fans wil probably have heat produced by the motors. I had some similar fans in my original incubator design, and I could not kep my incubator below 93 degrees. I used a temp gun to determine that the motor bodies were 115 degrees. This was keeping my incubator to warm.
I hope that helps,