16VAC25-50-530: Air and ventilation requirements

A permanent source of outside air shall be provided for each boiler room to permit satisfactory combustion of the fuel as well as proper ventilation of the boiler room under normal operating conditions.

A. The total requirements of the burners for all fired pressure vessels in the boiler room must be used to determine the louver sizes whether fired by coal, oil or gas; however, the minimum net free louvered area must not be less than one square foot. The following table or formula shall be used to determine the net louvered area in square feet:

Input BTU Per Hour

Required Air

Cu. Ft./Min.

Min. Net Louvered Area

Sq. Ft.

500,000

125

1.0

1,000,000

250

1.0

2,000,000

500

1.6

3,000,000

750

2.5

4,000,000

1,000

3.3

5,000,000

1,250

4.1

6,000,000

1,500

5.0

7,000,000

1,750

5.8

8,000,000

2,000

6.6

9,000,000

2,250

7.5

10,000,000

2,500

8.3

B. When mechanical ventilation is used instead of subsection A of this section, the supply of combustion and ventilation air to the boiler room and the firing device shall be interlocked with the fan so the firing device will not operate with the fan off. The velocity of the air through the ventilating fan shall not exceed 500 feet per minute and the total air delivered shall be equal to or greater than shown in this section.