035-17421-000 Rev B (700)
Unitary Products Group
9
After the thermostat is mounted, route the 24-volt control wir-
ing (NEC Class 2) from the thermostat to the indoor air han-
dler and outdoor unit. Route the control wiring into the
grommeted hole in the bottom of control box of the outdoor
unit. Using wire nuts connect to leads inside the low voltage
junction shown in Figure 6 and wiring diagrams shown in Fig-
ures 7 and 8.
Interconnecting control wiring must be a minimum of No. 18
AWG color coded insulated wires. If wire lengths increase
more than 90 feet, use No. 16 AWG wires, to prevent exces-
sive voltage drop.
NOTE: To eliminate erratic operation, seal the hole in the
wall at the thermostat with permagum or equivalent
to prevent air drafts affecting the anticipators in the
thermostat.
EVACUATION
It will be necessary to evacuate the system if the unit has
developed a leak during shipment or was, for any other rea-
son, opened to the atmosphere. If a leak is suspected, leak
test to locate the leak. Repair the leak and test again.
To verify if the system has no leaks, simply close the valve to
the vacuum pump suction to isolate the pump and hold the
system under vacuum. Watch the micron gauge for a few
minutes. If the micron gauge indicates a steady and continu-
ous rise, it’s an indication of a leak. If the gauge shows a rise,
then levels off after a few minutes and remains fairly con-
stant, its an indication that the system is leak free but still
contains moisture and may require further evacuation if the
reading is above 500 microns.
SYSTEM CHARGE
The factory charge in the outdoor unit includes enough
charge for the unit and a most sold matched evaporator.
REFRIGERANT LINE CHARGES
The outdoor condensing unit may be connected to the indoor
evaporator coil using field supplied refrigerant grade copper
tubing that is internally clean and dry. Units should be
installed only with the tubing sizes for approved system com-
binations as specified in Tabular Data Sheet. The charge
given is applicable for total tubing lengths up to 15 feet. See
Application Data Form 690.01-AD1V for installing tubing of
longer lengths and elevation differences.
NOTE: Using a larger than specified line size could result in
oil return problems. Using too small a line will result in loss of
capacity and other problems caused by insufficient refriger-
ant flow. Slope horizontal vapor lines at least 1" every 20 feet
toward the outdoor unit to facilitate proper oil return.
Sweat connect units also include sufficient charge for 15 feet
of lines. Table 2 lists the refrigerant line charges.
The “TOTAL SYSTEM CHARGE” must be permanently
stamped on the unit data plate.
Total system charge is determined as follows:
1.
Determine outdoor unit charge from tabular data sheet.
2.
Determine indoor coil adjustment from tabular data
sheet.
3.
Calculate the line charge with the factors in Table 2 for
sweat lines in excess of 15 ft.
NOTE: The line charge over 15 feet should be included on the
data plate and must be added to the system.
4.
Total system charge = item 1 + item 2 + item 3.
5.
Permanently stamp the unit data plate with the total
amount of refrigerant in the system.
USE THE FOLLOWING CHARGING METHOD
WHENEVER ADDITIONAL REFRIGERANT IS
REQUIRED FOR THE SYSTEM CHARGE.
Measurement Method
A calibrated charging cylinder or accurate weighing device
must be used to add refrigerant. This is the only accurate
charging method for heat pumps in the heat pump mode.
Check flare caps on service ports to be sure they are leak
tight. DO NOT OVERTIGHTEN (between 40 and 60 inch-lbs.
maxi-mum).
Refrigerant charging should only be carried out by a
qualified air conditioning contractor with proper certi-
fication
Refrigerant charging should only be carried out by a
qualified air conditioning contractor with proper certi-
fication.
Table 2: REFRIGERANT LINE CHARGES
LIQUID OD
VAPOR OD
R-22 CHARGE OZ./FT.
3/8"
5/8"
0.66
3/8"
3/4"
0.68
3/8"
7/8"
0.70
3/8"
1-1/8"
0.76
