1. Determine your design conditions:
• Outdoor Dry-Bulb Temperature (DB)
• Outdoor Wet-Bulb Temperature (WB)
• Desired Indoor Dry-Bulb Temperature
(DT)
2. Determine the Design Sensible Heat Load (SHL) in BTU/H
3. Calculate the leaving air temperature (LAT) of the cooler:
• LAT = DB - [(DB - WB) * Ef]
Where Ef is 0.8 for most coolers & 0.9 for coolers with 12"
rigid media
4. Determine the Total CFM required:
• CFM = SHL / [1.08 * (DT - LAT)]
5. Determine the cooler(s) required. Refer to the Specification Charts
in the cooler brochure for the units' CFM ratings.
Notes:
• The
design temperature (DT) you choose will greatly affect the overall
CFM required. Choose a temperature that would feel comfortable. Remember
that an evaporative cooler is different than an air conditioner. You
can have the temperature a few degrees higher than you would an air
conditioner and feel very comfortable because of the added cooling
effect of the movement of moist air over the skin.
• Contact a local HVAC engineer or your Sales Engineer if you
need help approximating the Sensible Heat Load in the building.
If the heat load is not known you may use this method to approximate
the total CFM you will need. It assumes a commercial / light industrial
environment with normal heat loads.
If you have unusual heat loads, you should use the previous method.
1. Determine the volume of area that is to be cooled (ft^3).
• If the workspace has high ceilings,
you should consider only the worker
environment - normally up to about 10 feet above the floor.
2. Determine the approximate air change rate (min. per air change)
• Air change rate = (DB - WB) /
10
3. Determine the required CFM
• CFM = Volume / Air Change Rate
4. Determine the cooler(s) required. Refer to the Specification Charts
in the cooler brochure for the units CFM ratings.
