close up fireplace vent
I have an old fireplace (brick) that has a metal insert (heatilator) in it. it must've been put in 50 years ago.
there are 2 vents on each side. the bottom vents on each side are the intake and the top vents on each side throw out the heat.
i would like to close up these vents with brick/mortar. is there a problem with this? what would happen to the trapped air behind the metal insert and the brick fireplace?