I've been watching the Lowes clearance prices on the Englander stoves to replace my VC but I have some questions on the model 12 and 13. They both look the same size and the dimensions on the web site verify that but englander lists the 12 as 1.9+ cu. ft. box, the 13 is 1.8 cu. ft.. However the 13 is rated as heating 1800 sq ft. the 12 as 1000 sq ft. Also, why does the 12 have a flue damper the 13 none? Thanks!