Laars MagnaTherm HTD Series Installation And Operation Instructions Manual

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Laars MagnaTherm HTD Series Installation And Operation Instructions Manual Manual pdf 19 page image

Page 15HTD2.C.5 Combustion AirBoilers and water heaters must have provisions forcombustion and ventilation air in accordance with theapplicable requirements for Combustion Air Supply andVentilation in the National Fuel Gas Code, ANSI Z223 1;or in Canada, the Natural Gas and Propane InstallationCode, CSA B149.1. All applicable provisions of localbuilding codes must also be adhered to.This unit can take combustion air from the spacein which it is installed, or the combustion air canbe ducted directly to the unit. Combustion andVentilation air must be provided in either case.2.C.5.a Combustion Air From RoomIn the United States, the most common requirementsspecify that the space shall communicate with theoutdoors in accordance with Method 1 or 2. (See thefollowing descriptions.) Where ducts are used, they shallbe of the same cross-sectional area as the free area ofthe openings to which they connect.Method 1: Two permanent openings, one commencingwithin 12” (30 cm) of the top and one commencingwithin 12” (30 cm) of the bottom, of the enclosureshall be provided. The openings shall communicatedirectly, or by ducts, with the outdoors or spacesthat freely communicate with the outdoors. Whendirectly communicating with the outdoors, or whencommunicating to the outdoors through vertical ducts,each opening shall have a minimum free area of 1square inch per 4000 Btu/hr (550 square mm/kW) oftotal input rating of all equipment in the enclosure.When communicating to the outdoors through horizontalducts, each opening shall have a minimum free areaof not less than 1 square inch per 2000 Btu/hr (1100square mm/kW) of total input rating of all equipment inthe enclosure.Method 2: One permanent opening, commencingwithin 12” (300 mm) of the top of the enclosure, shallbe permitted. The opening shall directly communicatewith the outdoors or shall communicate through avertical or horizontal duct to the outdoors or spacesthat directly communicate with the outdoors and shallhave a minimum free area of 1 square inch per 3000Btu/hr (734 square mm/kW) of the total input rating ofall equipment located in the enclosure. This openingmust not be less than the sum of the areas of all ventconnectors in the confined space.Other methods of introducing combustion andventilation air are acceptable, providing they conform tothe requirements in the applicable codes listed above.In Canada, consult local building and safety codes or, inabsence of such requirements, follow CAN/CSA B149.