I bought a tabletop lamp dimmer at the home center for about $10. It plugs between the heat light and the outlet and has a long cord to a slider control. I can adjust the brightness (and thereby the heat output) easily. Dimming make incandescent bulb last longer too.
Thermostats in brooders are "overkill" IMO, just watch the chicks and adjust the brightness of the lamp until they mostly sleep in a circle at the outer edge.
True but I figured to make my life easier
Also, if they are sleeping on the outer edge, I would say it is set a bit too high. Typically they would sleep in a group.