Use the following charging method whenever additional refrig-
erant 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).
SYSTEM OPERATION
See Figure 11 to trace the flow of refrigerant through the
system.
WITH POWER TO UNIT AND THERMOSTAT IN COOLING
POSITION.
1. Reversing valve is energized through thermostat system
switch to position refrigerant circuit for cooling operation. In
the cooling cycle, discharge gas is pumped to the outdoor
coil which is the condenser. The indoor coil is the evapora-
tor.
2. If fan switch is in “ON” position, a circuit is made through
blower relay to provide continuous blower operation.
3. When thermostat cooling contact closes, a circuit is made
to energize contactor and start the system, if the compres-
sor has been off for 5 minutes. With fan switch in “AUTO”
position, a circuit is made from thermostat cooling contact
through blower relay to provide blower operation.
4. System will cycle with thermostat demand to provide cool-
ing as needed.
WITH POWER TO UNIT AND THERMOSTAT IN HEATING
POSITION
1. Reversing valve is de-energized to position refrigerant
circuit for heating operation. In the heating cycle, discharge
gas is pumped to the indoor coil which is the condenser.
The outdoor coil is the evaporator.
2. If fan switch is in “ON” position, a circuit is made through
blower relay to provide continuous blower operation.
3. When first stage of thermostat heating contact closes, a
circuit is made through the control to energize contactor
and start the system, if the compressor has been off 5
minutes. With fan switch in “AUTO” position, a circuit is
made from thermostat heating contact through blower relay
to provide blower operation.
4. The system will cycle in response to thermostat signal to
provide heating as needed.
5. Supplemental electric heaters are energized by second
stage of heating thermostat.
FIGURE 11 - HEAT PUMP FLOW DIAGRAM
FLOW
CONTROL
DEVICE
(COOLING)
INDOOR
COIL
FIELD INSTALLED BI-FLOW LIQUID STRAINER / DRYER
COMPRESSOR
4-WAY REVERSING VALVE*
SUCTION
ACCUM.
OUTDOOR
COIL
COOLING CYCLE FLOW
HEATING CYCLE FLOW
*SHOWN IN
COOLING
POSITION
FIELD CONNECTED LINE
FIELD CONNECTED LINE
FLOW CONTROL DEVICE (HEATING)
515.26-N5Y
10
Unitary Products Group
