343.2.3 VENT CONFIGURATION3.2.3.1 LEGEND3.2.3.2 CONDITIONS THAT MUST ALWAYS BE MET• Total vent length, including elbows (see 3.2.3.3), must not exceed 40 ft. H + V ≤ 40 ft.• The first 8 ft. of vent (from the fireplace) must always be covered with the insulating sleeve provided with thefireplace; no matter the model or configuration type.• The first 6 in. of vent (from the fireplace) must be vertical.• The horizontal run, including elbow equivalents (see 3.2.3.3), must not exceed 3 times the vertical rise when itis greater than or equal to 1.33 ft. (16 in.) and less than or equal to 10 ft.H ≤ 3xV only if 1.33 ft. (16 in.) ≤ V ≤ 10 ft.Exception: 6 in. ≤ V ≤ 16 in. Hmax. = 48 in. (4 ft.)• Maximum of 4 elbows for the entire exhaust length.• Minimum of 1 ft. (0.3 m) is required between two vent elbows.• No vent section should have a downward slope.3.2.3.3 ELBOW EQUIVALENT FOR HORIZONTAL VENT LENGTHElbow angleHorizontal vent lengthequivalent (He)in. ft.1º 0.4 0.03315º 6 0.530º 12 145º 18 1.590º 36 3Note1: The first elbow has a value of 0 in horizontal vent length. The above table is valid for the 2nd, 3rd, and4th elbows.CAUTION:No vent section should slope downwards (from the fireplace to the exterior vent outlet).- ≤: less than or equal- ≥: greater than or equal- <: less than- >: greater than- V: vertical rise- H: horizontal run
