Just posted this on another thread reviewing the Little Giant Model 11300 Deluxe Incubator, manufactured by Miller Manufacturing:
"This is our first time incubating and I decided to go with this model because it had the most features of all the ones I looked at locally. Just put 41 eggs in it yesterday, after running it for two days. I am very concerned with the variability of temperature across the egg bed! I quickly checked egg shell temperatures with an accurate infrared gun, after running it for 24 hours, and they vary about 8 Degrees F, between 94 and 102! The eggs furthest from the heater, near the edge are the coldest. I make sure the top lid fits correctly, and currently have only the vent plug near the heater removed, per the instructions. Also, for some reason, the right half averages almost 2 degrees warmer than the left half! The room is at 71 Degrees, with no significant drafts, and I have no other heat sources near the bator. I don't want to crank it up any higher for fear of cooking the eggs near the heater. I know the fan is working because I can hear it, and I made sure the blades were turning. Does not seem to be much airflow, though. We will be lucky to get half of the fertilized eggs to hatch, at this rate.
The incubator's thermostat and temperature sensor seems fairly accurate, reading about 1 Degree high on mine. The thermostat maintains temp within 0.5 Degrees, where the sensor is located (on top of the eggs under the controller, per the instructions).
I am in Montana, with low humidity (now about 15%). I have found during preparational testing that if I put water in the outer two troughs only, the humidity in the incubator rises to 45-50%, and that if I fill both the outer and inner troughs, humidity rises to 60-75%. Note the four troughs in the middle are connected, so you can fill them all by pouring into only one of them. I use an Acurite temp/humidity gage in the bator and the humidity on the Acurite reads about 10% higher than the unit on my bator.
Anybody else experience this temperature variability problem with this unit or has solved this problem with other units? If this hatch turns out poorly I am thinking about adding a computer fan inside this unit to move the air around in a circular fashion, to supplement the Little Giant's factory method of blowing hot air straight down onto the eggs."
My advice on incubators, based on what I am experiencing so far, is perhaps to spend the extra $100 or so to get a higher quality incubator, or build one yourself that has some way to maintain a uniform temperature across the egg bed. And if you are really serious about chick production, go with a commercial unit. The Brinsea models seem to consistently get good reviews, they do not have high capacity, but might be perfect for us back yard chicken folks. I hope Miller Manufacturing reads this!