I have week old Freedom rangers & a couple of turkey poults in a brooder in my barn, today it was 9 degrees F at 7am..
I just use a regular light bulb, usually 75w with the reflector on it about 5 inches over the chicks heads. They come & go under it as they need.
I use a shelf unit with 3 shelves, wrapped around with hardward cloth, and then with a canvas tarp that holds in the heat.
I put the waterer near the light so it doesn't freeze. I have learned to put 2 lights in each section in case one bulb burns out during the night...I learned that the hard way.
I've been hatching & brooding during the winters for 3 years now.
As I get more young hatchlings, I move the older chicks down, so the upper shelf is the warmest.
Here are pictures of the unit when I was first building it.
The tarp is held on with plastic clamps. I have it so it opens in the middle right in front of the doors, so I only have to open the tarp enough to open a door.
You can't see the tarp well in the photos as I opened it up to expose the whole front for the photos. /the tarp covers the entire shelf from top to bottom when it is closed.
Sue