Would you argue the opposite for a central/interior chimney?
I have an interior chimney and put a block-off plate in. I cannot tell how much of a difference it makes since I never burned without but why heat the attic and outside? The installation takes maybe one hour and lasts 20+ years; one of the simplest energy efficiency improvements I ever made.
 
	 
	 
 
		 
 
		![[Hearth.com] Ok, you've convinced me to add a block off plate..... [Hearth.com] Ok, you've convinced me to add a block off plate.....](https://www.hearth.com/talk/data/attachments/145/145006-933cc91359f364ff2fc86b0904b1eb99.jpg?hash=xQJfORnWac)
 
 
		