Great! I was looking at Sunbeam on Amazon. So 2 of their king sized pads should do the trick then? http://www.amazon.com/Sunbeam-732-500-King-Heating-UltraHeatTechnology/dp/B000FGDDI0/ref=sr_1_4_a_it?ie=UTF8&qid=1463289556&sr=8-4&keywords=Heating+pad#customerReviews
This is going to be so much better than the silly heat lamps! I was thinking about adding some feather dusters to the inside of their cave. Good idea of no?
I am also doing it in the coop with the big girls. They are used to chicks so this should be a seamless transition. I am actually excited this time to brood chicks myself.
You're not going to have room in the cave for a feather duster, and it will interfere with the chicks making contact with the pads. This is not an ambient heating method, like heat lamps. It's contact with the heating pad that warms the chicks. The frame for the pads must be adjustable, to allow for the pads to be at about the level of the chicks' backs.