Specification
12
SELECTION PROCEDURE (WITH EXAMPLE)
1. Determine cooling and heating requirements at
design conditions:
Given:
Required Cooling Capacity (TC) 34,000 Btuh..........
Sensible Heat Capacity (SHC) 25,000 Btuh............
Required Heating Capacity 60,000 Btuh...............
Condenser Entering Air Temperature 95F(35C).......
Indoor--Air Temperature 80F(26C)edb 67F(19C)ewb.
Evaporator Air Quantity 1200 CFM..................
External Static Pressure 0.100 IN. W.C.................
Electrical Characteristics 208--1--60...................
2. Select unit based on required cooling capacity.
Enter Net Cooling Capacities table at condenser entering
temperature of 95F(35C). Unit 036 at 1200 cfm and 67F
(19C) ewb (entering wet bulb) will provide a total capacity of
34,200 Btuh and a SHC of 27,400 Btuh. Calculate SHC correction,
if required, using Note 4 under Cooling Capacities tables.
3. Select heating capacity of unit to provide design
condition requirement.
In the Heating Capacities and Efficiencies table, note that the single
phase unit 036090 will provide 73,000 Btuh with an input of
90,000 Btuh.
4. Determine fan speed and power requirements at
design conditions.
Before entering the air delivery tables, calculate the total static
pressure required. From the given example, the Wet Coil Pressure
Drop Table, and the Filter Pressure Drop Table:
External Static Pressure 0.100 IN. W.C
Filter 0.07 IN. W.C
Wet Coil Pressure Drop 0.180
IN. W.C
Total Static Pressure 0.287 IN. W.C
Enter the table for Dry Coil Air Delivery—Horizontal and
Downflow Discharge. At .287 IN. W.C. ESP, the closest speed to
1200 CFM is Med --Low (pink wire), which delivers 1213 CFM at
.3 in ESP.
5. Select unit that corresponds to power source
available.
The Electrical Data Table shows that the unit is designed to operate
at 208-- 1--60.
PY4G -- -- B