Trane WSC060-120 - Manual (Page 10)

10 PKGP-PRC004-EN
Selection
Procedure - SI Units
Cooling Capacity
Step 1
Calculate the building’s total and
sensible cooling loads at design
conditions. Use the Trane calculation
form or any other standard accepted
method.
Step 2
Size the equipment using Table PD-1.
Match the cooling loads at design
conditions.
Example: The following are the building
cooling requirements:
A
Electrical Characteristics: 380–415/50/3
B
Summer Design Conditions:
Entering Evaporator Coil: 27 DB/ 19 WB
Outdoor Ambient: 35
C
Total Cooling Load: 17.0 kW
D
Sensible Cooling Load: 11.7 kW
E
Airflow: 3,400 m
3 /hr
External Static Pressure: 130 Pa
F
Downflow Configuration
Table PD-1 shows that a WSC060AD has
a gross cooling capacity of 18.1 kW and
14.7 kW sensible capacity at 35 degree C
ambient and 3,400 m
3 /hr with 27 DB/19
WB air entering the evaporator.
To find the net cooling capacities, fan
motor heat must be subtracted.
Determine the total unit static pressure:
External Static 130 Pa
Standard Filter 1 in. 37 Pa
Economizer 46 Pa
Supplementary Electric Heat 21 Pa
Total Static Pressure 234 Pa
Note: The Evaporator Fan Performance
Table PD-9 has deducted the pressure
drop for a 25 mm filter already in the
downflow unit.
Therefore, the actual Total Static
Pressure is 234 – 37 = 197 Pa. With 3,400
m
3 /hr and 197 Pa, Table PD-9 shows 0.75
kW.
Note below the table gives a formula to
calculate Fan Motor Heat,
Fan Motor Heat (kW) =
1.144 x (Fan kW) + 0.132
= 1.144 x 0.75 + 0.132 = 1.0 kW
Net Total Cooling Capacity =
18.1 – 1.0 = 17.1 kW
Net Sensible Cooling Capacity =
14.7 – 1.0 = 13.7 kW
Heating Capacity
Step 1
Calculate the building heating load using
the Trane calculation form or other
standard accepted method.
Step 2
Size the equipment using Table PD-5 to
match the heating loads at design
conditions.
A
Total Heating Load: 16 kW
B
Outdoor Ambient (Winter) –9°C DB
C
Indoor Return Temperature: 21°C DB
D
Airflow: 3,400 m
3 /hr
Use the portion of Table PD-5 for the
WSC060AD to determine capacity at
winter design conditions. The
mechanical heating portion of the heat
pump will provide 8.3 kW.
Step 3
Because 8.3 kW is less than the
building’s required heating capacity at
winter design conditions, a
supplementary heater must be selected.
16 kW – 8.3 kW = 7.7 kW
From Table PD-9, at 380 volts, the 10.9
kW Heater will be adequate to do the
job.
10.9 kW 38.0 MBh
From Table ED-5 select heater
BAYHTRR418A (10.9 kW 380/50/3).
Air Delivery Selection
External static pressure drop through the
air distribution system has been
calculated to be 200 Pa. Enter Table PD-9
for a WSC060AD at 3400 m
3 /h and 200
Pa static pressure. The standard motor
will give the desired airflow.
Accessory Selection
Select accessories needed to
accommodate the application.