The beauty of the heating pad system is you can't overheat chicks, and the design of an enclosed "cave" helps hold chick body heat and protect against a much colder ambient temp.
I measured the temperature on the floor of the brooder just under the heating pad cave, which is at the height of the chicks' backs, and it was 85F. The pad is around 100F. I was brooding in spring when it was down into the 30s at night and 50s during the day.
If you felt your Sweet Heater get so hot to the touch it burned your hand, you have what killed the chicks. Chicks instinctively move away from heat when they absorb too much and toward it when they chill, like lizards and snakes do. The heating pad system is designed to be just the the right temperature for chicks to make direct contact with, and they will sleep all night, not needing to move away from the heat because it's not hot to the touch. I placed a folded wool blanket over the heating pad when it got into the 30s to help keep the heat from radiating upward away from the chicks.
During the day, chicks catch on very quickly that they need to go under it to warm up as they lose body heat. They can be seen runny around freely even though it's chilly enough for you to need a coat. They self regulate by running under it until they absorb enough heat to be off and running around again. Food is outside of the heating pad cave as is water.
My article about brooding outdoors is down in my signature line. Here's the thread introducing Mama Heating Pad.
https://www.backyardchickens.com/th...d-in-the-brooder-picture-heavy-update.956958/