Supply fans or PRVs 
A large number of buildings use exhaust fans and/or power roof ventilators to exhaust fumes, smoke, dust or other contaminants unavoidable in the operation of the business.  As a result, these buildings are frequently under a severe negative pressure. This condition can create problems in many areas of operation. Examples are: (1) reduced efficiency of exhaust systems that are working against each other; (2) down drafts in flues, that may extinguish pilot lights and cause explosions and tire; (3) severe drafts around windows, doors and other locutions when- air seeks to enter the structure.
     The solution to problems of this kind is usually found in the use of supply fans or "make-up" air ventilators. During the hot weather period, these fans become a valuable source of fresh, cooler, outside air to replace the superheated air being exhausted. If they arc correctly sized and coordinated with the exhaust fans, an effective ventilation system may be achieved. 

Supply Air PRV -- Type PS

If the exhaust and supply air requirements of a building have been carefully engineered and installed, and there continues to be a high instance of worker discomfort, the problem usually relates to the matter of air circulation. Typical examples of worker discomfort are found in areas where exhaust fans are roof mounted and air supply is through windows and wall openings. Air flow is generally from the window opening to the nearest roof exhauster. The cooling effect on the individuals in the area is negligible. To be effective, air flow must be at or near floor level. In this way, occupants obtain maximum benefit from the fresh, cooler air; they receive the added comfort of air circulation over their bodies and they are not adversely affected by the superheated air being exhausted from the building. 

 

The American Coolair Breeze Conditioning System 
A carefully engineered ventilation and cooling system frequently combines several methods of air movement to accomplish the desired results. Exhaust fans, power roof ventilators, supply fans, make-up air units and air circulators may all be utilized. American Coolair sales engineers with experience and training in the selection and use of this equipment can be consulted for advice in the design of the system and installation of its components. System components, practical limitations and common consideration involved in the design of an American Coolair Breeze Conditioning System are discussed in the following sections.