I'm retrofitting a ZC fireplace where I had a builder grade worthless ZC fireplace from 30 years ago. My question is what constitutes ZC as in dimensions. The attached snapshot of a ZC brochure requiring requiring 7 in of clearance on either side seems like a stretch on the ZC claim. Based on that liberal interpretation, I'm going to have to look at the diagrams of each manufacturer to see what how they define ZC.