When it comes to installing fans, contractors ask 1) Where can I save money? 2) Where can I save time? and 3) How can I reduce problems after the “equipment has been installed? There is nothing worse than hearing You are short on air because you installed it wrong.”
Saving money is critical for success, but the lowest fan bid does not always equate to the lowest installed cost. Greenheck Fan Corporation products have timesaving features and accessories that result in money savings for contractors. In reality, the contractor provides the equipment, the labor to install the fan, and all required components. If the manufacturer of the equipment can provide an option, accessory, or feature already installed, the contractor’s overall cost will be reduced. The following tips for installing fans properly to ensure effective airflow can save you time and money.
1. Make sure there are no obstructions close to the inlet or outlet of the fan (e.g., a damper, elbow, duct transition, or guard). Typically, allow 2.5 duct diameters (approximately 2.5 wheel diameters) of space away from both ends of the fan.
2. Avoid placing a damper too close to the inlet or outlet, which will cause an uneven flow of air. 3. Adding extra guarding can restrict the airflow through the fan. Avoid expanded metal guards; use thin wire guards if possible.
4. Avoid damper actuators that block 25 percent or more of the free area. They can add up to 1/2” of static pressure. Typically, large damper actuators can be mounted outside the duct.
5. Avoid elbows and transitions directly after inline fans. A good solution for commercial inline fans is to use a side discharge option. The fan acts as the elbow—the air discharges out the side of the fan, preventing poor outlet conditions.
6. Placing a damper too close to the propeller of a sidewall propeller fan will cause vibration. As a general rule of thumb, have at least one half of a propeller diameter between the damper and the propeller.
7. Be certain the wheel is rotating in the correct direction. An exhaust fan with a backward inclined wheel will exhaust air, even if it is rotating backwards. Remember, you have a 50/50 chance of wiring a three-phase motor correctly the first time. To change the rotation, reverse any two of three leads.
8. Utility sets are designed so the fan’s discharge can be rotated, eliminating the need for an elbow at the outlet. Performance will be greatly reduced if you do not use 2.5 duct diameters of straight outlet ductwork.
9. For fans with no inlet duct, the distance between the fan’s inlet and a wall or housing must be at least one inlet diameter to ensure proper performance.
10. When wiring the fan motor and the damper actuator, confirm that the wiring is correctly run so it does not get caught in the damper, preventing proper operation.
From a performance perspective, remember that the fans were originally tested under ideal conditions. If the fan is not installed the way it was tested, it will not perform as specified. If you encounter a jobsite problem, one of these timesaving installation tips may help you quickly resolve the issue.