Roof Ventilators for Reversible Building Ventilation

By: Oleg Tchetchel

NIS-CO Fan Co. makes now a truly reversible (exhaust and supply roof fan for general ventilating.

The Type CBRE recirculators are designed for use in commercial and industrial applications where there is sufiicient ceiling height to create a temperature differential between the floor and the ceiling. These applications include factories, warehouses and large commercial buildings.

CBRE Roof Recirculators function as regular power roof ventilators in warmer weather and as an energy-saving recirculation air system in cold weather. Each unit is equipped with a reversible fan that distributes warm ceiling air thoughout the plant and reduces the builing's heating requirements. With a flip of a switch it can function as a conventional roof ventilator. There are two unit types: 1) for exhaust and recirculation; 2) for exhaust, supply and recirculation.

Available fan wheel sizes are from 24" to 60", performances: to 50,000 CFM @ 1/2" WG.

The reversible propeller incorporates specifically engineered airfoil sections and hub size for optimal efficiency and physical strength. Alternate adjustable pitch propeller blades are turned 180 degrees to one another and a double orifice is attached to the fan panel.

Type HS PRVs reliably extract large volumes of hot gases and smoke regardless of building configuration, location and weather conditions. They withstand high temperatures for long periods of time.

Another reliable ventilation system that can operate during a fire is Canada Blower Type HS Heat and Smoke Roof Ventilator. It prevents smoke logging, allows people to escape quickly, minimizes damages to property and contents and enables firemen to attack the fire without hindrance. These power roof ventilators have the added advantage of providing normal day to day ventilation and in many cases can also be fitted with duct work for use in multi storey buildings.

The concept of venting smoke and heat was first outlined by Industrial Risk Insurers (IRI). Use of powered ventilation could eliminate the problems experienced with gravity vents. Specially designed roof mounted exhaust fans would mechanically vent heat and smoke under emergency fire conditions.

The unique Type HS power roof ventilators provide a solution for emergency heat and smoke venting that is dependable under the most extreme circumstances.

All critical components of HS PTV that exposed to the airstream are ferrous construction to withstand high temperature conditions. These heavy gauge materials prevent warping of fan parts and malfunction at high temperatures. This also insures years of trouble-free service in normal daily operation of the PRV.

Belt and bearings are protected from the air stream by enclosing them in a ventilated tube. Design of HS fan incorporates a heat slinger/impeller. It isolates the fan bearings from damaging heat and draws cooler outside air through the motor compartment and over the belt and bearings. A spring load, fusible link activated device automatically opens dampers when temperature at the fan reaches 165 F. Thei enables the fan to function as a gravity ventilator prior to powered operation.

Type HC Power Roof Ventilators have been tested to operate:

- conituously at 650 F;
- 3 Hours at 800 F;
- 1.5 Hours at 1000 F;
- 1/2 Hour at 1,200 F.

Additional information can be found at the NIS-CO Fan Co. web site

Oleg Tchechel
Industrial Air-Moving Process Designer
NIS-CO Fan Co.
[email protected]

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Additional information can be found at the NIS-CO Fan Co. web site Oleg Tchechel Industrial Air-Moving Process Designer NIS-CO Fan Co. [email protected]

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