The Ontario Building Code | Heat Circulating Duct Openings
9.22.9.4. Heat Circulating Duct openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings
(1) The clearance of combustible material above heat circulating duct openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings from those openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings shall be not less than,
(a) 300 mm where the combustible material projects not less than 38 mm from the face, and
(b) 150 mm where the projection is less than 38 mm.
9.22.10. fireplace Inserts and Hearth-Mounted Stoves