The purpose is to explain why Pfannenberg air conditioners have their default setpoint set to 95/95˚F
The intent of the cooling unit is not to keep the cabinet cold as we are not trying to comfort cool a drive. Our factory setpoint is 95°f as VFD drives have an operational temp of 100°f, so to rid the heat building up in the cabinet while maintaining the drives operational temperature too cold would cause condensation.
Most of the time the internal fan of the cooling unit will just be running, conditioning the air maintaining the temps in the 90’s. Once the temperature increases the cooling unit refrigeration circuit turns on and the external fan and compressor run, and the exit temp would be 20 degrees lower while we convert the hot air to cool.
• Bracketed in “green” is the cooling capacity of the unit represented in British thermal
units and watts.
• Bracketed in “red” is the nominal range of temperatures inside the enclosure that the unit
can effectively cool.
• Bracketed in “blue” is the nominal range of temperature outside the unit or the ambient
conditions that the unit can effectively cool.
It is clear to see from the graphical representation of hysteresis for this example cooling unit,
that the enclosure and ambient temperatures can drastically affect the cooling capacity of the unit.
If the ambient temperature is lower than the enclosure temperature, the cooling capacity can exceed the upper limit of 1300 BTU/hr, leading to significant condensate buildup and icing inside the unit or enclosures, which can result in failures. On the other hand, if the ambient temperature is higher, the unit may struggle to provide the necessary cooling capacity for the enclosure.
If the enclosure temperature is set to a higher temperature, the unit will be using less energy but also the components inside the enclosure might not be able to handle those higher temperatures. If the unit is set to the low-end temperature, the unit will be running for long, which sacrifices efficiency and increase the risk of condensation buildup. Setting the cooling units to 95˚F ambient temperature and 95˚F enclosure temperature provides a sound compromise between cooling the enclosure and limiting the accumulation of condensation.