Air conditioners and filtered fan systems are the two primary methods used to cool electrical enclosures. The difference comes down to how heat is removed and how much each system depends on the surrounding environment.
Air Conditioners (Closed-Loop Cooling)
Actively remove heat using a refrigeration cycle
Keep the enclosure sealed from outside air
Operate independently of ambient conditions
Cool internal temperatures below ambient
Provide protection from dust, moisture, and corrosive contaminants
Filtered Fan Cooling (Open-Loop Cooling)
Move ambient air through the enclosure to dissipate heat
Rely on outside air temperature and air quality
Cannot cool below ambient air temperature
Introduce outside air into the enclosure
Provide a simpler, lower-cost cooling approach when conditions allow
Choosing between air conditioning and filtered fan cooling depends on heat load, ambient temperature, and environmental exposure.
Cooling method selection depends on heat load, environment, and how much control is required inside the enclosure.
Cooling Method | System Type | Best Use |
Air Conditioners | Closed-loop | High heat loads, harsh or outdoor environments |
Filtered Fan Cooling | Open-loop | Moderate heat loads, clean and controlled environments |
Why Cooling Strategy Matters
Electrical enclosures are designed to protect equipment from environmental conditions. Once the enclosure is sealed, heat becomes the next challenge.
Internal heat from equipment and external heat from ambient conditions accumulate. If that heat is not managed correctly, component performance degrades, equipment lifespan is shortened, and failures will follow.
Cooling is not an add-on. It is part of the enclosure system design.
Option 1: Electrical Enclosure Air Conditioners
Electrical enclosure air conditioners actively remove heat from inside the enclosure using a refrigeration cycle, without introducing outside air.
What that gives you:
Controlled internal temperatures, even below ambient
Protection from dust, moisture, and corrosive contaminants
Reduced risk of condensation forming inside the sealed enclosure
Reliable performance in outdoor and high-temperature environments
This is the preferred solution when environmental exposure is high or heat load exceeds what airflow can manage.
Option 2: Filtered Fan Cooling
Filtered fan systems move ambient air into and out of the enclosure to dissipate heat.
This is a simpler and often more economical solution when environmental conditions allow.
What that gives you:
Lower upfront cost
Lower energy use
Continuous airflow through the enclosure
Simpler maintenance, usually limited to filter replacement
Effective cooling when ambient air conditions support it
Filtered fan systems work best when heat loads are moderate, the surrounding air is clean, and outside temperatures support heat removal.
They are not a universal replacement for air conditioning. They are a condition-dependent solution based on ambient temperature and air quality.
Air Conditioners vs Filtered Fan Cooling: Key Differences
The difference is not just the equipment. It is how each system depends on the surrounding environment.
One system isolates the enclosure from the environment. The other depends on it.
Air conditioners:
Use closed-loop cooling
Keep the enclosure sealed
Actively remove heat
Work independently of outside air quality
Can cool below ambient temperature
Filtered fan systems:
Rely on ambient airflow
Introduce outside air into the enclosure
Are limited by surrounding temperature and air quality
Cannot cool below ambient temperature
Work best when conditions are stable and clean
One system isolates the enclosure from the environment. The other depends on the external environment.
Cooling Method Selection Begins with Heat Load
If heat loads, typically measured in BTUs or watts, are high or environmental exposure is a concern, air conditioning is usually required. If heat loads are moderate and the surrounding environment is clean and stable, filtered fan cooling may be sufficient.
When Air Conditioners Are the Right Solution
Air conditioners are the correct choice when environmental risk is high or heat becomes the limiting factor. That typically includes:
Outdoor installations exposed to weather
High ambient temperatures
Direct sun exposure
Corrosive or coastal environments
High-density equipment or elevated internal heat loads
Applications where uptime is critical
In these environments, introducing outside air is often the wrong move. The enclosure must remain sealed while heat is actively removed.
When Filtered Fan Cooling Makes Sense
Filtered fan cooling makes sense when the enclosure is operating in a cleaner, more predictable environment. That typically includes:
Indoor or sheltered applications
Lower heat loads
Moderate ambient temperatures
Conditions where outside air can be safely used
Projects where energy efficiency and lower system cost are priorities
When conditions support it, filtered fan systems can provide reliable cooling with less complexity.
Common Mistakes When Choosing a Cooling Method
Most mistakes come from treating cooling as an add-on instead of part of the enclosure system.
Assuming filtered airflow will always be enough
If outside air is hot, airflow cannot cool the enclosure below that temperature. In fact, internal temperatures will always be higher than ambient temperature due to heat generated by the equipment itself.Ignoring environmental exposure
Dust, moisture, salt, and contaminants do not stop being a problem just because the enclosure has filters.Choosing based on upfront cost alone
The less expensive cooling option is not the less expensive solution if it leads to downtime, shortened equipment lifespan, or field failures.Treating cooling as an afterthought
Cooling should be evaluated as part of the enclosure design, not added after the fact.
The NEMACO™ Approach: Engineered Beyond the Standard
At NEMACO™, cooling is engineered as part of the enclosure system from the beginning. We evaluate:
Heat load from installed equipment
Ambient temperature and solar exposure
Moisture, humidity, and corrosion risk
Long-term performance expectations
We also provide free thermal calculations to determine the correct cooling strategy before the enclosure is built.
Most enclosure manufacturers design to meet a rating. We design for how the enclosure will actually perform in the field. When conditions are at their worst, enclosure performance is no longer theoretical. It has to be proven. We help you prepare for those conditions before they become a problem.
NEMACO™ enclosures are backed by a 5 to 15-year warranty depending on configuration, providing added confidence in long-term performance for applications where environmental exposure and reliability cannot be compromised.
Frequently Asked Questions (FAQs)
What is the difference between open-loop and closed-loop enclosure cooling?
Open-loop cooling, used in filtered fan systems, pulls ambient air through the enclosure to remove heat. The enclosure is exposed to whatever contaminants may exist in the outside air. Closed-loop cooling, used in electrical enclosure air conditioners, removes heat through a refrigeration cycle without introducing outside air. The enclosure stays sealed. The distinction matters because open-loop performance depends entirely on the quality and temperature of the surrounding environment.
When should I use an electrical enclosure air conditioner instead of a filtered fan?
Use an electrical enclosure air conditioner when heat loads are high, ambient temperatures are elevated, or environmental exposure makes outside air a risk to enclosure performance.
Can filtered fan systems cool below ambient temperature?
No. Filtered fan systems rely on outside air, so they cannot reduce internal temperature below the temperature of the surrounding environment.
Are filtered fan systems suitable for outdoor enclosures?
They can be, but only when air quality, temperature, and moisture levels support that approach. In many outdoor applications, a sealed cooling strategy is the safer choice.
Do air conditioners affect enclosure ratings?
Properly designed electrical enclosure air conditioners maintain the integrity of the enclosure while providing active cooling. But the cooling system has to be selected and integrated correctly. An improperly integrated unit can introduce leak points that compromise the enclosure's rating and defeat the environmental protection it was designed to provide.
How do I know which cooling method is right for my application?
The right method depends on heat load, ambient temperature, humidity, and environmental exposure. Thermal evaluation is the most reliable way to determine the correct approach.
Is filtered fan cooling the cheaper option?
It is often the lower upfront-cost option, but total cost depends on how well the solution matches the operating environment. A lower-cost cooling method that leads to failures is not the lower-cost solution.
Why do electrical enclosure air conditioners reduce the risk of condensation?
The electrical enclosure stays sealed, so humid outside air cannot enter and contact the cooler internal surfaces. That contact is what causes condensation. Filtered fan systems introduce outside air continuously, which means humidity comes with it. In environments where temperature swings are significant, moisture can accumulate on components and cause corrosion or electrical failures over time.
