Can one use a 6 inch coaxial vent system with the Mendota D-40 gas fireplace insert that is placed in a masonry fireplace?
The web site .pdf copy of the installation manual shows that for a masonry fireplace, they use a 4 inch colinear direct vent system where the combustion air intake rises about four or five feet above the appliance. For a zero clearance fireplace, they use a coaxial vent system.
I believe I should prefer a system that takes combustion air directily from the vent cap at the top of the chimney.
Thank you, Al