Rheem RPVS Series Installation, Operation & Maintenance Instructions Manual page 19

FP2 Sensor Installation
An FP2 sensor with violet wiring is shipped loose with the
compressor section. This is the air coil low temperature
protection sensor. Install this sensor on the refrigerant line
between the indoor expansion valve and the air coil using
thermal compound and the supplied mounting clips. Ensure
that the sensor makes good thermal contact with the refrigerant
line and insulate the sensor.
Air coil low temperature protection will not be active if this
sensor is installed incorrectly or is not installed.
Add-On Heat Pump Applications
The indoor coil should be located in the supply side of
the furnace to avoid condensation damage to the furnace
heat exchanger for add-on heat pump applications. A high
temperature limit switch should be installed as shown
in Figure 9b just upstream of the coil to de-energize the
compressor any time the furnace is energized to avoid
blowing hot air directly into the coil, elevating refrigerant
pressures during operation. The heat pump will trip out on
high pressure lockout without some method of disengaging
the compressor during furnace operation. Alternatively, some
thermostats with "dual fuel" mode will automatically de-
energize the compressor when second stage (backup) heat
is required.
The TXV should be brazed into place as shown in Figure 8,
keeping the "IN" side toward the compressor section. The
TXV has an internal check valve and must be installed in the
proper direction for operation. Always keep the valve body
cool with a brazing shield and wet rags to prevent damage
to the TXV. Attach the bulb to the suction line using the
supplied hose clamp. Be careful not to overtighten the clamp
and deform the bulb.
NOTICE! The air coil should be thoroughly washed with a
fi lming agent, (dishwasher detergent like Cascade) to help
condensate drainage. Apply a 20 to 1 solution of detergent
and water. Spray both sides of coil, repeat and rinse
thoroughly with water.
Evacuation and Charging the Unit
LEAK TESTING - The refrigeration line set must be pressurized
and checked for leaks before evacuating and charging the unit.
To pressurize the line set, attach refrigerant gauges to the service
ports and add an inert gas (nitrogen or dry carbon dioxide) until
pressure reaches 60-90 psig [413-620 kPa]. Never use oxygen or
acetylene to pressure test. Use a halogen leak tester or a good
quality bubble solution to detect leaks on all connections made
in the fi eld. Check the service valve ports and stem for leaks. If
a leak is found, repair it and repeat the above steps. For safety
reasons do not pressurize system above 150 psig [1034 kPa].
System is now ready for evacuation and charging.
Turn service valves full out CCW (see Table 6) and then turn
back in one-half turn to open service ports. Add the required
refrigerant so that the total charge calculated for the unit and
line set is now in the system. Open the service valve fully
Refrigeration Installation
counter clockwise so that the stem will backseat and prevent
leakage through the schrader port while it is not in use.
Start unit in the heating mode and measure superheat and
subcooling values after 5 minutes of run time. See tables
13a through 13d for superheat and sub-cooling values.
Superheat is measured using suction temperature and
pressure at the compressor suction line. Subcooling should
be measured using the liquid line temperature immediately
outside the compressor section cabinet and either the liquid
line service valve pressure or the compressor discharge
pressure. Note that diff erent values from tables 13a through
13d will be obtained due to the pressure losses through the
condenser heat exchanger. Adding refrigerant will increase
sub-cooling while superheat should remain fairly constant
allowing for a slight amount of hunting in TXV systems.
This increase in subcooling will require 5 minutes or so
of operation before it should be measured. After values
are measured, compare to the chart and go to "FINAL
EVALUATION."
PARTIAL CHARGE METHOD - Open service valve fully
counterclockwise and then turn back in one-half turn to
open service port. Add vaporized (Gas) into the suction side
of the compressor until the pressure in the system reaches
approximately 100-120 psig. Never add liquid refrigerant into
the suction side of a compressor. Start the unit in heating
and add gas to the suction port at a rate not to exceed
fi ve pounds [2.27 kg] per minute. Keep adding refrigerant
until the complete charge has been entered. Superheat is
measured using suction temperature and pressure at the
compressor suction line. Subcooling should be measured
using the liquid line temperature immediately outside the
compressor section cabinet and either the liquid line service
valve pressure or the compressor discharge pressure. Note
that diff erent values from tables 13a through 13d will be
obtained due to the pressure losses through the condenser
heat exchanger. Adding refrigerant will increase sub-cooling
while superheat should remain fairly constant allowing for
a slight amount of hunting in TXV systems. This increase in
subcooling will require 5 minutes or so of operation before it
should be measured. After values are measured, compare to
the chart and go to "FINAL EVALUATION."
FINAL EVALUATION -In a split system, cooling subcooling
values can be misleading depending on the location of the
measurement. Therefore, it is recommended that charging
be monitored in the heating mode. Charge should be
evaluated by monitoring the subcooling in the heating mode.
After initial check of heating sub-cooling, shut off unit and
allow to sit 3-5 minutes until pressures equalize. Restart unit
in the cooling mode and check the cooling superheat against
Tables 13a through 13d. If unit runs satisfactorily, charging
is complete. If unit does not perform to specifi cations the
cooling TXV (air coil side) may need to be readjusted (if
possible) until the cooling superheat values are met.
R e s i d e n t i a l S p l i t
R e v. : 1 3 M a r c h , 2 0 1 5
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