1. Are air conditioners/cooling units airflow paths important in an electronic enclosure system?
Yes, internally the airflow path should be as long as possible to capture the hot air from the top of the enclosure and send cool air below the equipment within the enclosure. A 6" gap (from a blower style fan system) could short cycle the air, which prevents complete cooling of the entire enclosure.

2. Should you choose a Filterfan® that drives cool ambient air into the cabinet or a Filterfan® that exhausts hot internal air out of the cabinet?
Pressurizing the enclosure by driving cool ambient air into the bottom of the cabinet is the best solution for maintaining a dirt-free enclosure. The pressure prevents dust from entering through non-filtered areas such as broken door seals or poorly sealed conduit entrances.

Exhausting the hot air in some applications (where there is a large heat producing item such as a VFD) is actually thermally more efficient versus the pressurizing method. However, you have just created a large vacuum effect within the cabinet.

Click here for more information on a dual fan approach that uses the best of both worlds.

3. How can you determine the proper cooling capacity of an air conditioner/cooling unit?
One of the biggest misconceptions about cooling units is that the marketing BTU capacity of the cooling unit is the same for all application conditions. As the performance chart shows, this is definitely not the case.

As you allow for higher temperature inside an enclosure, the capacity of the air conditioner grows. Many of the cooling unit providers only offer the maximum ambient temperature (125° F in most cases) as the only capacity reference. But what good does this do when the internal temperature is also that 125 F temperature?

Reading a performance chart:

• The target internal temperature (Ti) is designated by the horizontal lines within the chart (77° F, 95° F, 113° F are shown)
• The ambient temperature (worst case) is shown on the X-axis>
• By drawing an intersecting line from the X-axis to the target Horizontal line (Internal Temp), the true cooling capacity of the unit can be found on the Y-axis.

Note: Pfannenberg provides performance charts for all our cooling units.

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