Below is a pic of my prefab zero clearance before my stove install. I have a Hearth Heater that is vented from the back with a tee attached to a liner going right up the opening you see in the pic. There is insulation in the small gap between the pipe/liner and the prefab opening. I'm not having any problems heating our home with this stove, but I've been reading alot about the benefits of a blockoff plate. Just not sure how much I'd benefit (if at all) from putting one in since it seems as though the top of my prefab looks to be acting like a blockoff plate (though it's not insulated).
Any thoughts?
Any thoughts?