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How to Increase Pressure on a Centrifugal Fan

The pressure generated by a centrifugal fan depends on a number of factors. If the increase in pressure is needed for an extended period of time, it is usually easier to purchase a new fan with different characteristics than to modify the pressure output of the existing fan. However, there are a few tricks you can try to change the pressure for short periods. It should be noted that excessive pressure above the manufacturer's rating can damage the fan.

Things You'll Need

Metal benders
Outlet size reducer
New motor
Pulley
Belt

Instructions

- 1
  Check the rotation speed of the motor that powers the fan. If the fan and motor are directly coupled, replace the motor with a larger motor with a slightly higher speed than the existing motor. The motor will need to have at least the same amount of torque as the original motor. If the motor is connected to the fan with a belt-and-pulley system, go to Step 2.
- 2
  Remove the fan pulley. The fan pulley is usually larger than the motor drive pulley. Replace the fan pulley with a slightly smaller pulley, then reinstall the pulley with a new, smaller belt. This setup will increase the speed of the fan and the pressure it generates.
- 3
  Reduce the size of the fan's outlet. This forces the air exiting the fan to speed up. As the opening deceases, the air pressure increases. You can do this by installing an outlet reducer that can be bolted onto the front of the fan. Smaller fans can use PVC pipe reducers.

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