Buffalo Fan Co. has introduced a new reliable and efficient air make-up unit designs for industrial building ventilation. In industrial plants where there is a high density of employees and many manual operations involved, an improvement in the environment can produce substantial benefits in terms of increased production, reduced errors, and a decline in complaints and absenteeism among employees.

Direct Gas-Fired Air Heating Systems are a class of equipment utilized primarily in industrial and commercial environments to provide for worker comfort. To a lesser extent, these systems are used to condition air for process and finishing applications such as material drying and paint curing.

These systems have gained widespread use due to the fact that they are inexpensive to build, maintain, and operate compared to other furnace types of comparable heating capacity.

The feature that differentiates a Direct Gas-Fired Heating System from other types of heating equipment is its burner system. A "trough" or "line" burner is installed directly in the supply air stream. Combustion products are introduced into the building space during operation.

The key advantages are simplicity and efficiency. No heat exchanger is required. This eliminates component installation and maintenance costs. With no heat transfer losses, the unit is nearly 100% efficient.

The primary disadvantage is the introduction of waste products into the airstream. For this reason, both ANSI Z83.4/CSA3.7 and ANSI Z83.18 standards state: "Heaters covered by this standard are intended for use in industrial and commercial applications."

ANSI Z83.18 states further that: "Heaters covered by this standard are not intended for use in any area containing sleeping quarters." Carbon Monoxide and Nitrogen Dioxide are the primary pollutants. These are limited to no more than 5.0 PPM for CO and

0.5 PPM NOX, a fraction of OSHA allowable Permissible Exposure Limits(PEL).

Negative Air Pressure inside industrial facility can create problems such as:

• Exhaust fans losing performance, as the building pressure becomes negative

• Pilot light outages and exhaust system failure on natural draft gas equipment

• Cold air drafts and infiltration of dirt and contamination from outside

• Difficulty opening or closing exterior doors

A Direct Gas-Fired Air Heating System may be used in an industrial or commercial application for any or all of the following purposes:

• Make-Up Air Heating – Air is introduced to a building to replace air being exhausted.

• Space Heating – A unit provides primary or supplementary heating to a building space.

• Space Pressure Control – Building or Room Pressurization is held within a range.

In temperate climates or during mild weather, moderate amounts of make-up air can be supplied by simply opening windows or overhead doors. However, this is usually not the case in industrial and commercial facilities. Forced ventilation Make-up air is required.

Direct Gas-Fired Make-up Air Units supply tempered and filtered air to the indoor environment. In summer, a direct-fired unit may be used as an air handler, with the heater disabled. By adding a DX or evaporative cooling section to the unit, it may be used to supply conditioned air year round.