Trane WSC060-120 manual Selection Procedure - SI Units

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 m3/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

14.7kW sensible capacity at 35 degree C ambient and 3,400 m3/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 actualTotal Static Pressure is 234 – 37 = 197 Pa. With 3,400 m3/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

NetTotal 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 theTrane calculation form or other standard accepted method.

Step 2

Size the equipment usingTable 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 m3/hr

Use the portion ofTable 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

FromTable PD-9, at 380 volts, the 10.9 kW Heater will be adequate to do the job.

10.9 kW 38.0 MBh

FromTable 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. EnterTable PD-9 for a WSC060AD at 3400 m3/h and 200 Pa static pressure. The standard motor will give the desired airflow.

Accessory Selection

Select accessories needed to accommodate the application.

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