9. Selection procedure
Single Package
20
_ 50Hz, R410A
Single Package
Selection Procedure
Heating
Step 4.
The capacity estimated at step #3 is the gross capacity of the selected unit. The generated heat
from indoor motor is a function of CFM & static pressure. The total unit static pressure is as follows:
Evaporator fan motor performance table has deducted the pressure drop for filter already in the unit.
Therefore, the actual total static pressure is 0.7 in. Aq.
(When installing the economizer to the product, it should be added pressure drop of Economizer
Fresh Damper (OA) 10% to total static pressure.)
With 8,000CFM and 0.7 in Aq., Evaporator Fan Performance EK-H2408C02 (English) table shows
3.6 BHP for this unit.
FAN MOTOR HEAT;
3.1 x Fan BHP = MBH
3.1 x 3.6 = 11.20 MBH
Now subtract the fan motor heat from the gross cooling capacity of the unit;
Step 5.
If the selected unit performance will not meet the required load, either total or sensible cooling, the
next higher size unit should be selected.
Step 1.
Calculate the building heating load using the ASHRAE calculation or from other standard accepted
method.
Step 2.
From Heating Capacity EK-H2408C02 (English), The heating capacity is 238,000 Btu/h at 8,000
CFM with 39.2°F outdoor DB temperature and 68°F indoor DB temperature. The required heating
capacity is 200,000 Btu/h.
Since heating capacity 238,000 Btu/h is greater than required heating capacity 200,000 Btu/h. So
additional electric heat is not required.
Step 3.
If the selected unit performance will not meet the required load. The additional electric heater should
be selected from Electric Heating Capacity table.
Net cooling capacity
235.9 MBH - 11.2 MBH = 224.7 MBH
Net sensible cooling
186.4 MBH - 11.2 = 175.2 MBH
• MBH = kBtu/h
External Static(Duct system)
0.70 in. Aq.
Standard Filter
0.1 in. Aq.
Economizer Fresh Damper (OA) 10%
Refer to the economizer applied models.
(From table Accessory Static Pressure Drops)
Total static pressure
0.8 in. Aq.