Patterson-Kelley MACH-05 manual Air Inlet Requirements, Electrical Connections at Rear of Boiler

MACH® Series Gas-Fired Boiler

An external electrical disconnect (not supplied with the boiler) with adequate overload protection is required. The boiler must be grounded in accordance with local codes or in the absence of such requirements, in the U.S. with National Electrical Codes, ANSI/NFPA No. 70 latest edition and in Canada to the current Canadian Electrical Code, Part I, CSA C22.1.

Note: A dedicated earth ground (green wire) is required to avoid nuisance shutdowns. Do not ground through the conduit. It is also important that proper polarity be maintained.

Note: Refer to Terminal Block Assignments (Section 6.1.1).

120 Volt	Low Voltage
	Control Junction
Electrical Control
	Box
Junction Box

Electrical Connections at Rear of Boiler

3.5COMBUSTION AIR

Combustion air must be free from dust, lint, etc. The presence of such materials in the air supplied to the burner could cause nuisance "Low Air" shutdowns or premature burner failure. The boiler should not be operated during construction while the possibility of drywall dust, demolition dust, etc. exists.

The combustion air supply must be completely free of chemical fumes which may be corrosive when burned in the boiler. Common chemicals which must be avoided are fluorocarbons and other halogenated compounds, most commonly present as refrigerants or solvents, such as freon, trichlorethylene, perchlorethylene, chlorine, etc. These chemicals,

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Installation

when burned, form acids which quickly attack the boiler and the boiler stack. The result is improper combustion and premature boiler failure.

Provisions for combustion and ventilation air must be in accordance with Section 5.3, Air for Combustion and Ventilation, of the National Fuel Gas Code, ANSI Z223.1, latest edition, or applicable provisions of the local building codes. In Canada, combustion air openings shall comply with CSA B.149 Installation Code. The formula is 1 sq. in. per 1,000 Btu/hr of gas input not less than 100 sq. in. The location shall be neither more than 18", nor less than 6" above the floor level.

The boiler room shall be provided with two openings to ensure adequate combustion air and proper ventilation. One opening should be 6 to 12 inches above the floor and the other 6 to 12 inches below the ceiling, preferably on opposite walls. The size of each opening is determined by whether air is taken from inside or outside the building. In Canada, ventilation air openings shall be at least 10% of the cross sectional area required for combustion air, but not less than 10 square inches. It is to be located at the highest practical point communicating with outdoors.

WARNING!

Under no circumstances shall the boiler room ever be under a negative pressure. Particular care should be taken when exhaust fans, compressors, air-handling units or other equipment may rob air from the boiler.

3.5.1 Air Inlet Requirements

If air is taken directly from outside the building, each opening (minimum of two) should have a net free area of 1 square inch for each 4,000 Btu per hour of total boiler input. For instance, 112.5 square inches are required for 450,000 Btu per hour input.

When air is taken from the outdoors through a vertical duct, 1 square inch per 4,000 Btu per hour is required. If a horizontal duct is used, 1 square inch per 2,000 Btu per hour is required, i.e., 225 square inches for 450,000 Btu per hour input.