Crestron electronic 3.5, 2.5, 1.5 service manual 7Combustion Air from Outside Single Opening

1 Determine boiler location

Combustion and ventilation air requirements for appliances drawing air from the equipment room

Provisions for combustion and ventilation air must be in accordance with Air for Combustion and Ventilation, of the latest edition of the National Fuel Gas Code, NFPA 54 / ANSI Z223.1, in Canada, the latest edition of CGA Standard B149 Installation Code for Gas Burning Appliances and Equipment, or applicable provisions of the local building codes.

The equipment room MUST be provided with properly sized openings and/or be of sufficient volume to assure adequate combustion air and proper ventilation for all gas fired appliances in the equipment room to assure adequate combustion air and proper ventilation.

The requirements shown are for the appliance only; additional gas fired appliances in the equipment room will require an increase in the net free area and/or volume to supply adequate combustion air for all appliances.

No combustion air openings are needed when the appliance is installed in a space with a volume NO LESS than 50 cubic feet per 1,000 Btu/hr of all installed gas fired appliances and the building MUST NOT be of “Tight Construction”3.

A combination of indoor and outdoor combustion air may be utilized by applying a ratio of available volume to required volume times the required outdoor air opening(s) size(s). This must be done in accordance with the National Fuel Gas Code, NFPA 54 / ANSI Z223.1.

Installation & Operation Manual

Figure 1-5_Combustion Air Through Ducts

2.If combustion and ventilation air is taken from the outdoors using a duct to deliver the air to the equipment room, each of the two openings should be sized based on a minimum free area of one square inch per 2000 Btu/hr (11 cm2 per kW) of input (see FIG. 1-5).

Figure 1-6_Combustion Air from Interior Space

3. If air is taken from another interior space combined with the equipment room:

(a) Two spaces on same story: Each of the two openings specified above should have a net free area of one square inch for each 1000 Btu/hr (22 cm2 per kW) of input, but not less than 100 square inches (645 cm2) (see FIG. 1-6).

(b) Two spaces on different stories: One or more openings should have a net free area of two square inches per 1000 Btu/hr (44 cm2 per kW).

Figure 1-4_Combustion Air Direct from Outside

1. If air is taken directly from outside the building with no duct, provide two permanent openings to the equipment room each with a net free area of one square inch per 4000 Btu/hr input (5.5 cm2 per kW) (see FIG. 1-4).

12 Figure 1-7_Combustion Air from Outside - Single Opening