For an AirBoss design, the average temperature of the space is a constant ~75° as well as the return air temperature due to the air changes produced by the AirBoss as shown in Figure 5 and Figure 6.
Figure 5. Space temperature profile of an AirBoss system.
Figure 6. Entering and leaving air temperatures of an RTU.
When there is a call for cooling or heating, the RTU only has to cool/heat the entire volume by 1°. Using Equation 1 and assuming the return air temperature is 75°, the calculated cooling requirement is shown below.
MBHs=10,000×20℉×1.0812,000=18 tons
Since the calculated requirement is 18 tons, a 20-ton unit is selected to handle the cooling requirement of the space. Under these conditions, the unit capacity is only reduced by 3% to 19.4 tons. This reduction in capacity is caused by the airflow of the system being larger that the nominal airflow of the unit (8000 CFM). Even though there is a slight reduction in capacity, the unit is more efficient than a unit in a conventional design.
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