Refrigeration control of the condenser fans effects the overall performance of the entire system.
What are condenser fan pressure controls?
Commercial and industrial refrigeration systems are designed to maintain the correct product temperature year round.
Condenser fan pressure controls play a critical role in this process. They keep the refrigerant pressures stable.
How do they do work?
Expansion valves will not work correctly at lower pressures. There must be enough high side pressure to force the liquid refrigerant through the valve into the evaporator.
That's the job of the fan pressure controls. They cycle the condenser fan motors on and off as the high side pressure goes up and down.
During the warmer times of year the condenser fan motors run continually. But in cooler weather the fan pressure controls cycle the fan motors.
Cycling these motors stabilizes the refrigeration equipment.
These controls normally have two settings- the cut-in pressure and the differential.
The cut-in setting is simply the pressure that causes the control to close contacts and bring on the fan motor.
The differential setting subtracted from the cut-in pressure gives you the cut-out pressure.
Example: If you have a condenser fan pressure control with a cut-in setting of 225 psi and differential setting of 30 psi. The cut-out setting would be 195 psi.
The fan motor would start when the high side pressure reached 225 psi and continue to run until the pressure dropped to 195 psi.
The expansion valve would be metering refrigerant in a fairly stable 195-225 psi range.
On very cold days the fan may not start at all! It all depends upon the condenser pressure.
What are the proper settings?
Of course there is no correct number. It depends upon the refrigerant being used.
Try to maintain the normal high side pressure of a typical summer day. Remember, refrigeration equipment is designed and sized to cool product during the warmest days.
The coolers I service and maintain use R22. I live in Florida. So my condenser fan controls are set to keep a high side pressure of 200-250 psi year round.
Refrigeration control using condenser fan controls is not optional.
If you live on the equator in Africa, maybe you have an argument!
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