OK, here we go --
Incubator stability varies a lot. Most manufactures recommend incubators be in a room that 70 - 80 degrees. Forced air machines being better than still air at being stable, but they have their limits too. I found that forced air machines have cool spots, I've check them. GQF machines are cooler at the bottom.
Thermometers, most, don't advertise an accuracy of better tan 2 degrees or 2%. comparing thermometers can be a crazy experience. The best thermometers for incubating eggs are a 6" one from Lyon Incubator & on from Kessler Instrument , it only registers a temperature of 94 to 108) (both can be found on-line) I've used these for a least 20 years of incubating & have found that they can't be beat. The one draw back is that they are mercury filled & a little hard to read, but if you want confidence in temperature of your incubators, these will give you that. I consider temperature & humidity THE most important factor in achieving good hatches. without that you leave yourself open to a lot of problems in the form of drowned chicks, stuck chick, chicks hatching early or late, just to name a few
Spend the money for good thermometers, spend the time getting your incubators set-up a week in advance. Having the eggs hatch exactly on the 21 day is really fun
Incubator stability varies a lot. Most manufactures recommend incubators be in a room that 70 - 80 degrees. Forced air machines being better than still air at being stable, but they have their limits too. I found that forced air machines have cool spots, I've check them. GQF machines are cooler at the bottom.
Thermometers, most, don't advertise an accuracy of better tan 2 degrees or 2%. comparing thermometers can be a crazy experience. The best thermometers for incubating eggs are a 6" one from Lyon Incubator & on from Kessler Instrument , it only registers a temperature of 94 to 108) (both can be found on-line) I've used these for a least 20 years of incubating & have found that they can't be beat. The one draw back is that they are mercury filled & a little hard to read, but if you want confidence in temperature of your incubators, these will give you that. I consider temperature & humidity THE most important factor in achieving good hatches. without that you leave yourself open to a lot of problems in the form of drowned chicks, stuck chick, chicks hatching early or late, just to name a few
Spend the money for good thermometers, spend the time getting your incubators set-up a week in advance. Having the eggs hatch exactly on the 21 day is really fun
(I really don't have room for dozens of chickens. Two hatches this year, one a test hatch with inexpensive eggs and a hatch with the pricey pure breads. Which one would you do in class?? 
