INSTALLATION INSTRUCTIONS
R
−
410A Split System Heat Pump
428 01 5106 00
15
A. UNITS WITH COOLING MODE TXV
Units installed with cooling mode TXV require charging by
the subcooling method.
1. Operate unit a minimum of 15 minutes before
checking charge.
NOTE:
If outdoor unit has a 2
−
speed fan motor,
motor will operate in low speed when outdoor
ambient temperature is below 82
_
F (28
_
C). Pull
the BRN/YEL low voltage wire off the fan control
and the unit will default to high speed fan for
servicing. Reconnect wire after servicing.
2. Measure liquid service valve pressure by attaching
an accurate gage to service port.
3. Measure liquid line temperature by attaching an
accurate thermistor type or electronic
thermometer to liquid line near outdoor coil.
4. Refer to unit rating plate for required subcooling
temperature.
5. Refer to Figure 16. Find the point where required
subcooling temperature intersects measured
liquid service valve pressure.
6. To obtain required subcooling temperature at a
specific liquid line pressure, add refrigerant if liquid
line temperature is higher than indicated or reclaim
refrigerant if temperature is lower. Allow a
tolerance of
"
3
_
F (
|
1.7
_
C).
B. UNITS WITH INDOOR PISTON
Units installed with indoor pistons require charging by the
superheat method.
The following procedure is valid when indoor airflow is
within
"
21 percent of its rated CFM.
1. Operate unit a minimum of 15 minutes before
checking charge.
2. Measure suction pressure by attaching an
accurate gage to suction valve service port.
3. Measure suction temperature by attaching an
accurate thermistor type or electronic
thermometer to suction line at service valve.
4. Measure outdoor air dry
−
bulb temperature with
thermometer.
5. Measure indoor air (entering indoor coil) wet
−
bulb
temperature with a sling psychrometer.
6. Refer to Figure 14. Find outdoor temperature and
evaporator entering air wet
−
bulb temperature. At
this intersection, note superheat. Where a dash
(
−−
) appears on the table, do not attempt to charge
system under these conditions or refrigerant
slugging may occur. Charge must be weighted in,
adding or removing 0.6 oz/ft of 3/8 liquid line above
or below 15 feet (4.6m) respectively.
7. Refer to Figure 15. Find superheat temperature
(from #6 above) and suction pressure. At this
intersection, note suction line temperature.
8. If unit has a higher suction line temperature than
charted temperature, add refrigerant until charted
temperature is reached.
9. If unit has a lower suction line temperature than
charted temperature, reclaim refrigerant until
charted temperature is reached.
10. When adding refrigerant, charge in liquid form into
suction service port using a flow
−
restricting
device.
11. If outdoor air temperature or pressure at suction
valve changes, charge to new suction line
temperature indicated on chart.
12. Optimum performance will be achieved when
the operating charge produces 5
_
to 6
_
F
suction superheat at suction service valve
with 82
_
F (28
_
C) outdoor ambient and 80
_
F
(27
_
C) dry bulb (67
_
F / 19
_
C) wet bulb) indoor
temperature (DOE “B” test conditions) at rated
airflow.