Page 15
XP15 SERIES
manifold gauge center port hose from vacuum pump.
Attach the manifold center port hose to a dry nitrogen
cylinder with pressure regulator set to 150 psig (1034
kPa) and purge the hose. Open the manifold gauge
valves to break the vacuum in the line set and indoor
unit. Close the manifold gauge valves.
7. Shut off the dry nitrogen cylinder and remove the
manifold gauge hose from the cylinder. Open the
manifold gauge valves to release the dry nitrogen from
the line set and indoor unit.
8. Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set
and indoor unit until the absolute pressure does not
rise above 500 microns (29.9 inches of mercury) within
a 20−minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9. When the absolute pressure requirement above has
been met, disconnect the manifold hose from the
vacuum pump and connect it to an upright cylinder of
HFC−410A refrigerant. Open the manifold gauge valve
1 to 2 psig in order to release the vacuum in the line set
and indoor unit.
10. Close manifold gauge valves and shut off the
HFC−410A cylinder and remove the manifold gauge
set
.
SERVICING UNITS DELIVERED VOID OF CHARGE
If the system is void of refrigerant, clean the system using
the procedure described below.
1. Use nitrogen to pressurize the system and check for
leaks. Repair all leaks.
2. Evacuate the system to remove as much of the
moisture as possible.
3. Use nitrogen to break the vacuum and install a new
filter drier in the system.
4. Evacuate the system again. Then, weigh the
appropriate amount of HFC−410A refrigerant as listed
on unit nameplate into the system.
5. Monitor the system to determine the amount of
moisture remaining in the oil. It may be necessary to
replace the filter drier several times to achieve the
required dryness level.
If system dryness is not
verified, the compressor will fail in the future.
Start−Up Procedures
IMPORTANT
If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start−up to
prevent compressor damage as a result of slugging.
1. Rotate fan to check for frozen bearings or binding.
2. Inspect all factory− and field−installed wiring for loose
connections.
3. After evacuation is complete, open the liquid line and
vapor line service valves to release the refrigerant
charge (contained in outdoor unit) into the system.
4. Replace the stem caps and tighten as specified in
Operating Service Valves
on page 3.
5. Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit’s
nameplate. If not, do not start the equipment until you
have consulted with the power company and the
voltage condition has been corrected.
6. Set the thermostat for a cooling demand. Turn on
power to the indoor indoor unit and close the outdoor
unit disconnect switch to start the unit.
7. Recheck voltage while the unit is running. Power must
be within range shown on the nameplate.
8. Check system for sufficient refrigerant by using the
procedures listed under
Testing and Charging
System
.
TESTING AND CHARGING SYSTEM
This system uses HFC−410A refrigerant which operates at
much higher pressures than HCFC−22. The pre−installed
liquid line filter drier is approved for use with HFC−410A
only. Do not replace liquid line filter drier with components
designed for use with HCFC−22.
NOTE −
This unit is NOT approved for use with coils which
use capillary tubes as a refrigerant metering device.
SETTING UP TO CHECK CHARGE
1. Close manifold gauge set valves. Connect the center
manifold hose to an upright cylinder of HFC−410A.
2. Connect the manifold gauge set to the unit’s service
ports as illustrated in figure 25.
S
low pressure gauge to
vapor service port
S
high pressure gauge to
liquid service port
COOLING MODE INDOOR AIRFLOW CHECK
Check airflow using the Delta−T (
D
T)
process as illustrated
HEATING MODE INDOOR AIRFLOW CHECK
Blower airflow (CFM) may be calculated by energizing
electric heat and measuring:
S
temperature rise between the return air and supply air
temperatures at the indoor coil blower unit,
S
voltage supplied to the unit,
S
amperage being drawn by the heat unit(s).
Then, apply the measurements taken in following formula
to determine CFM:
CFM =
Amps x Volts x 3.41
1.08 x Temperature rise (F)
CALCULATING CHARGE
If the system is void of refrigerant, first, locate and repair
any leaks and then weigh in the refrigerant charge into the
unit. To calculate the total refrigerant charge:
Amount
specified
on
nameplate
Adjust amount for
variation in
line set length
(table in figure 27)
Additional charge
specified per
indoor unit
match−up
(tables 6 through 11)
Total
charge
+
+
=
