Unit Start-Up - Lennox SL25XPV Series Installation Instructions Manual

UNIT START-UP

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 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 valve stems to release the refrigerant
charge (contained in outdoor unit) into the system.
4 - Replace the stem caps and tighten to the value
listed in table 2.
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 - Connect manifold gauge set for testing and charging
or use the Lennox Dealer Setup App to monitor the
pressures and temperatures of the refrigeration
system.
7 - Turn on power to the indoor unit and close the
outdoor unit disconnect switch to start the unit.
Start-up and testing should be performed with the
unit operating at the maximum cooling capacity
(100% capacity). The unit can be operated at
maximum capacity by entering the test mode at
the thermostat or using the Lennox Dealer Setup
App. The S30 Test Mode can be selected by going
to Menu> Advanced Settings> View Dealer Control
Center> Test and then select Cooling - Maximum
Rate Test.
8 - Recheck voltage while the unit is running. Power
must be within range shown on the unit nameplate.
9 - Check system for sufficient refrigerant using the
procedures outlined under Checking Refrigerant
Charge.
HEAT PUMP CONTROL – DEFROST OPERATION
A full description of the heat pump control can be found
in the detailed installation and service procedure manual
available on LennoxPros.com.
The master control measures differential temperatures
to detect when the system is performing poorly because
of frost build-up on the outdoor coil. The heat pump con-
trol self-calibrates when the defrost system starts and
after each system defrost cycle. The heat pump control
monitors ambient temperature, outdoor coil temperature,
and total run-time to determine when a defrost cycle is
required. The coil temperature sensor is designed with a
spring clip to allow mounting to the outside coil tubing. The
location of the coil sensor is important for proper defrost
operation.
Detailed information is given in the XP25 Installation and
Service Procedures Corp. 1252-L11, which is available on
LennoxPros.com.
NOTE – The heat pump control accurately measures the
performance of the system as frost accumulates on the
outdoor coil. This typically will translate into longer running
time between defrost cycles as more frost accumulates
on the outdoor coil before the heat pump control initiates
defrost cycles.
OPERATING MANIFOLD GAUGE SET AND SERVICE
VALVES
The liquid and vapor line service valves are used for re-
moving refrigerant, flushing, leak testing, evacuating,
checking charge and charging.
Each valve is equipped with a service port which has a
factory-installed valve stem. Figures 13 and 14 provide
information on how to access and operate both angle- and
ball-type service valves.
When servicing or repairing heating, ventilating and air
conditioning components, ensure the fasteners are appro-
priately tightened. Table 1 lists torque values for fasteners.
TABLE 1
Parts
Service valve cap
Sheet-metal screws
Machine screws #10
Compressor bolts
Gauge port seal cap
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.
Using Manifold Gauge Set
When checking the system charge, only use a manifold
gauge set that features low loss anti-blow back fittings.
Manifold gauge set used with HFC-410A refrigerant sys-
tems must be capable of handling the higher system oper-
ating pressures. The gauges should be rated for use with
pressures of 0 - 800 psig on the high side and a low side
of 30" vacuum to 250 psig with dampened speed to 500
psi. Gauge hoses must be rated for use at up to 800 psig
of pressure with a 4000 psig burst rating.
Page 19
Torque Requirements
– TORQUE REQUIREMENTS
Recommended Torque
8 ft.-lb.
16 in.-lb.
28 in.-lb.
90 in.-lb.
8 ft.-lb.
IMPORTANT
11 NM
2 NM
3 NM
10 NM
11 NM