I know other people use box heaters in their brooders, but we never had a large enough brooder for the size box we felt we would want in there. We have some new big brooders built now and tried a box heater in one. It is fantastic! That is all we will be using for our brooders from now on. Out of a batch of 117 chicks, we have only lost two so far in the brooder, and those two were showing weakness right out of the hatchery box. Ours doesn't have legs, we have it suspended in the brooder so that we can raise and lower it as the weather and age of the chicks changes. Definitely the best way to brood we have found so far and even a money saver. We used to need four or five lamps in our large brooders at 250 watts each. The box lets us get away with only two 250 watt lamps.
