Managing Humidity and Moisture with Evaporative Coolers: Best Practices


Recommendations to Prevent Moisture Build-Up in Humid Conditions

1.    Maximize Fan Speed: Use the highest fan speed on humid days for increased airflow.

2.    Increase Exhaust Openings: Open doors/windows to increase airflow and let moist air out.

3.    Nighttime Ventilation: Run the cooler on vent mode at night when it is cooler outside.


Rules of Thumb for Ventilation / Efficient Exhausting of Air to Optimize Performance

1.    Exhaust Area: Ensure open windows/doors are twice the size (area) of the air vents.

2.    Optimal Window/Door Openings: Open windows/doors farthest from the vents in every room a vent is installed.

3.    Door and Tissue Paper Test: If a door can’t stay slightly open or tissue paper sticks to the screen, increase the exhaust area.

By following these guidelines, you can optimize your evaporative cooler's performance and maintain a comfortable indoor environment.



Optimizing Your Evaporative Cooler for Maximum Cooling Efficiency


Evaporative coolers are a fantastic solution for cooling spaces, especially when sized and designed correctly. To ensure you get the best performance from your evaporative cooler, it's crucial to get the size, number of outlets, and their placement right. Here are some common issues that can arise from mistakes in these areas:

  • Incorrect sizing
  • Improper number of outlets
  • Poor placement of outlets

By addressing these factors, you can optimize the efficiency and effectiveness of your evaporative cooler.


Wrong Sizing:

  • Excessive Humidity: An oversized cooler can add too much moisture to the air, leading to high humidity levels.
  • Inefficient Cooling: An undersized cooler may struggle to lower the temperature effectively, leaving the space uncomfortably warm.
  • Higher Energy Consumption: Both oversized and undersized coolers can lead to higher energy use, either by overworking to cool the space or by running inefficiently.


Incorrect Number of Outlets

Too Few Outlets:

  • Poor Air Distribution: Not enough outlets mean cool air isn’t spread evenly, causing some areas to remain warm and others to become overly humid.
  • Localized Humidity Pockets: Insufficient outlets can create humid spots, leading to condensation.
  • Reduced Cooling Efficiency: Without enough outlets, the cooler can't evaporate water efficiently, resulting in higher humidity and less cooling.


Too Many Outlets:

  • Reduced Airflow Velocity: More outlets can slow down the air, making cooling less effective.
  • Inconsistent Cooling: Some areas may get more air than others, causing hot spots.
  • Increased Humidity: Low airflow can make the cooling process less effective, increasing humidity.
  • Higher Energy Use: The system may use more energy to cool the space, raising costs.


General rule of thumb, to calculate the correct number of outlets for your evaporative cooler based on it's airflow capacity (L/s@80 pascals). Divide the total airflow capacity of the cooler by the airflow capacity of each outlet.

A heat load calculation on a house plan, performed by a qualified air conditioning representative with ductwork design experience can be used to confirm this.


Example: 

Number of 400mm outlets / registers needed for an evaporative cooler with a capacity of 2540 L/s at 80 pascals:

  • Minimum number of outlets: 2540L/s divided by 400L/s = 6.35
  • Maximum number of outlets: 2540L/s divided by 350L/s = 7.25


Since you can't have a fraction of an outlet, you would need between 6 to 7 outlets to ensure optimal performance. This range accounts for the variability in the air flow capacity of the 400mm outlets / registers.


Airflow Capacities for Various Outlet Sizes:

•    Duct 300mm/Register 350mm: 250-300 L/s

•    Duct 350mm/Register 400mm: 350-400 L/s

•    Duct 400mm/Register 450mm: 450-500 L/s

•    Duct 450mm/Register 500mm: 550-600 L/s


Poor Placement of Outlets:

  • Uneven Cooling: Poorly placed outlets can lead to uneven cooling, with some areas getting too much air and others not enough.
  • Hot Spots: Incorrect placement can cause certain areas to remain warm, reducing overall comfort.
  • Increased Humidity: Poor placement can also lead to areas with higher humidity, as the air isn't circulated properly.

For evaporative coolers, it's generally recommended to place the outlet registers on the inside of the room, opposite to open windows or doors. This setup helps create a crossflow of air, drawing the cool air across the room and pushing the warm air out through the open windows.


Opposite Openings: Position the registers on the opposite side of the room from open windows or doors to facilitate effective cross-ventilation.


Solutions:

To avoid these problems, ensure your evaporative cooler is properly sized for your space, with the right number of outlets placed strategically for even air distribution. This will help maintain a comfortable temperature, balanced humidity levels, and efficient energy use.


We strongly recommend that for detailed calculations, use a comprehensive cooling load calculation method or consult an HVAC professional. This ensures that your system is tailored to your specific needs, providing optimal performance and comfort.