Starting The Unit In Gas Heating Mode; Heating Shut-Down; Final Installation Checklist - Trane 4DCY4024 Installer's Manual

1. Be sure the comfort control is configured to power up in the
OFF mode, or be prepared to change the comfort control to
OFF just as soon as power is applied to the thermostat in the
steps below.
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. Change the thermostat mode to Emergency Heat and
adjust the heating setpoint slightly above the room
temperature.
2. When the comfort control calls for heat, the system operates
as follows:
a. The combustion blower is energized.
b. The pressure switch is closed.
c. The gas valve opens and the ignitor lights the burner.
d. Allow the comfort control to cycle on and off a few times
in Emergency Heat mode to check out the control system
and burner operation characteristics. For the *CONT802
and *CONT803 Comfort Controls if the call for heat lasts
longer than 10 minutes, these controls will transition to
high fire automatically.
3. With the burners operating, check the manifold pressure with
a manometer. Do not exceed recommended pressures.
4. Adjust the unit to obtain an air temperature rise with that
specified on the unit nameplate.
NOTE: For manifold pressures and orifice sizes for gas with
other BTU ratings, contact the local gas utility.
pressure should be 1.8 (low) to 3.5 (high) inches water
column (+0.1). Input must not exceed the value shown on
the nameplate.
5. Set the comfort control the desired temperature setting and
the unit will function automatically.
Starting the Unit in the Gas Heating Mode
1. Check to make sure all grilles and registers are open and all
unit access doors are closed before start-up.
2. Purge the gas supply line of air by opening the union ahead
of the unit. When the odor of gas is detected, retighten the
union and wait five (5) minutes before proceeding.
3. Open the main gas valve(s) and turn on the unit power
supply.
4. Set the comfort control to Emergency Heat and adjust the
heating setpoint slightly above the room temperature.
5. The combustion blower motor should energize. The main
burners should light within 20-25 seconds. Initial start may be
delayed somewhat if the unit has not been purged and air is
trapped in the gas line.
NOTE: Blue smoke produced by the heat exchanger during
the initial burner firing is caused by a thin film of oil on the
surface of the heat exchanger. This oil will burn off quickly.
6. Allow the comfort control to cycle on and off a few times
at a rate of not more than once every thirty (30) seconds.
Check both the control operation and the burner operating
conditions.
7. Increase the heating setpoint significantly so that the
comfort control will transition to high fire automatically. For
the *CONT802 and *CONT803 Comfort Controls, there is
a 10 minute delay before the transition occurs. Make the
following manifold pressure check on high fire.
MANIFOLD PRESSURE
1. Connect a manometer to the pressure boss at the outlet side
of the unit's gas valve. Read the manifold pressure with the
main burners firing. See figure 18, page 18.
2. If the manifold pressure reading does not match the value
indicated on the unit nameplate, the unit pressure regulator
must be adjusted as follows:
a. Remove the cover screw on the gas regulator located on
the front side of the unit's gas valve.
b. Turn the adjusting screw clockwise to increase manifold
pressure or counterclockwise to decrease manifold
pressure.
3. Check the temperature rise during furnace operation to insure
that it falls within the range specified on the unit nameplate.
4. If the temperature rise noted is outside of the specified limits,
adjust the indoor airflow to cause the temperature rise of the
heat exchanger to fall within the required range.

HEATING SHUT-DOWN

Set the comfort control to OFF or adjust the heating set point to
Manifold
below room temperature.

Final Installation Checklist


Does the unit run and operate as described in the section on
Sequence of Operation, page 24, in response to the room
thermostat?

Are the condenser fan and indoor blower operating correctly
with proper rotation and without undue noise?

Is the compressor operating correctly and has the system been
checked with a charging chart?

Has the voltage and running current been checked to determine
if it is within limits?

Has the thermostat been checked for calibration and the air
discharge grilles adjusted to balance the system?

Has the ductwork been checked for air leaks and
condensation?

Has the furnace manifold pressure been checked and
adjusted if necessary?
Installer's Guide
Page 23