I just ordered one so I hope it works. the lamps are so difficult to control. Brinsea has a nice sale right now if you haven't heard already!You can't use them if the room is too cold. I use one in the garage and it gets down to 40 in there at night(Gotta love California!). If you are using the 20 with bantams, you can remove one of the sides and leave it at an angle for the small chicks.
To answer your question, The eco glow is like the mother hen. If the chicks are cold, they stand up and make contact with the black warm part. I have been using mine for a year now and have had hundreds of chicks under them. Not a single one has died from being too cold or too hot. You do not need thermometers with it and you do not need to worry about catching the house on fire. And like a mother hen, they do not heat the area up to 95 degrees.
They pay for themselves in electricity savings in a month or so too.
I hope this helps!
I thought I was finished hatching, checked on the chicks drying in the incubator and one of the 3 remaining eggs has pipped.
