Fireplace #1: Butterfly Damper 3 Feet above the Firebox
These high-up butterfly center pivot dampers are usually in prefabricated zero clearance fireplaces made by Heatelator. Here are the characteristics:
The damper handle that opens the circular center pivot damper is usually on the outside lintel face of the fireplace.
You will notice that there are horizontal slats cut in the sheet metal just below the closed damper.
Those slats gives you a pretty good place to tuck in a Standard Chimella. The Chimella has a 2 foot long spring loaded handle. Here is a video on how the Chimella works. When you watch the video be sure to see that part that shows you how to snug up the Chimella by pressing the collar with the purple dot. This will be very important for this particular application.
The Standard Chimella works on any size opening under 16″x16″. So take a quick measurement of the area of the slats (image 1-3) to ensure the area you are covering is less than 16″x16″. Otherwise you may have to bump up to a Large Chimella.