Trane 4YCY4024, Installer'S Manual

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Page 22
Installer’s Guide
Starting the Unit in the Cooling Mode
To start the unit in the cooling mode, set the comfort control to
COOL and to a setting below room temperature. The condenser
(outdoor) fan motor compressor and evaporator (indoor) fan motor
will operate automatically.
NOTE: See the section on “Sequence of Operation” for a de-
scription of the cooling operating sequence.
Operating Pressures
After the unit has operated in the cooling mode for a short period of
time, install pressure gauges on the gauge ports of the discharge
and suction line valves. Check the suction and discharge pressures
and compare them to the normal operating pressures provided in
the unit’s
SERVICE FACTS.
Thermostat Heat Anticipator
Set the heat anticipator of the thermostat to equal the amperage
draw of the gas valve
IMPORTANT: Upon completion of wiring, check all electrical
connections, including factory wiring within the unit.
Make sure all connections are tight. Replace and secure all electri-
cal box covers and access panels before leaving the unit or turning
on the power to the unit.
Step 5—Unit Startup
Pre-Start Quick Checklist
〿
Is the unit properly located and level with the proper clearance?
See Figure 4.
〿
Is the duct work correctly sized, run, taped, insulated, and
weatherproofed with proper unit arrangement? See Ductwork
Installation section.
〿
Is the gas piping correctly sized, run, trapped, and purged of air?
See Gas Piping section.
〿
Is the condensate line properly sized, run, trapped, and pitched?
〿
Is the filter of the correct size and number? Is it clean and in
place?
〿
Is the wiring properly sized and run according to the unit wiring
diagram?
〿
Are all the wiring connections, including those in the unit, tight?
〿
Has the unit been properly grounded and fused with the recom -
mended fuse size? See Wiring Data.
〿
Is the thermostat level, correctly wired, well located, and set for
the proper heat anticipation?
〿
Have the air conditioning systems been checked at the service
ports for charge and leak tested if necessary?
〿
Does the condenser fan and indoor blower turn free without
rubbing, and are they tight on the shafts?
〿
Has the indoor blower speed been determined and the proper
speed been set? See the Unit Wiring Diagram.
〿
Has all work been done in accordance with applicable local and
national codes?
〿
Are all covers and access panels in place to prevent air loss and
safety hazards?
NOTE: Do not use the PRESSURE CURVES from the unit's SER-
VICE FACTS to determine the unit refrigerant charge. The correct
charge is shown on the unit nameplate. To charge the system
accurately, weigh in the charge according to the unit nameplate
and check subcooling against the Subcooling Charging Table in
the SERVICE FACTS.
Voltage
With the compressor operating, check the line voltage at the unit.
The voltage should be within the range shown on the unit name-
plate. If low voltage is encountered, check the size and length of
the supply line from the main disconnect to the unit. The line may
be undersized for the length of the run.
Cooling Shut Down
Set the comfort control to OFF or to a setting above room temperature.
Heating Cycle
These units are equipped with a solid-state ignition control that lights
the burners each time the thermostat calls for heat. The burners
are extinguished during the OFF cycle.
The gas heating section of the unit can be started using the follow-
ing procedure:
1. Be sure the comfort control is at its lowest setting and the power
to the unit is off.
a. Turn the main shutoff valve on the gas supply line ON.
b. Turn or switch the manual valve on the combination gas
valve to the ON position.
2. Be sure the burner compartment access panel is in place.
a. Turn on the electrical power to the unit.
b. Turn the comfort control to the highest setting in the heating
cycle.
3. As the comfort control calls for heat, the system cycles as fol -
lows:
a. The combustion blower is energized.
b. The pressure switch is closed.
c. The gas valve opens and the ignitor lights the burner.
d. Cycle the thermostat on and off a few times to check out the
control system and burner operation characteristics.
4. With the burners operating, check the manifold pressure with
a manometer. Do not exceed recommended pressures.
5. Adjust the unit to obtain an air temperature rise within the range
that is specified on the unit nameplate.
NOTE
: For manifold pressures and orifice sizes for gas with
other BTU ratings, contact the local gas utility. Manifold pressure
should be 1.8 (low) to 3.5 (high) inches water column (+0.1).
Input must not exceed the value shown on the unit nameplate.
6. Set the heat anticipator of the comfort control to equal the
amperage draw of the gas valve, approximately 0.7.
7. Set the comfort control at the desired temperature setting and
the unit will function automatically.
Starting the Unit in the Gas Heating Mode