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035-14370-000
control module and the gas valve if any of the following condi-
tions are present. Refer to Figure 35 for tubing connections.
1LP
UPFLOW
2LP
1LP
DOWNFLOW / HORIZONTAL
FIG URE 35 : PRESSURE SW ITCH TUBING RO UTING
1.
Blockage of combustion air piping or terminal. (1LP)
2.
Blockage of vent piping or terminal (1LP).
3.
Failure of combustion air blower motor (1LP).
4.
Blockage of condensate drain piping:
• Upflow units (1LP)
• Downflow/Horizontal Units
• Downflow (1LP)
• Horizontal Left (1LP)
• Horizontal Right (2LP)
Limit Control
There are high temperature limit control(s) located on the fur-
nace vestibule panel near the gas valve. These are automatic
reset control and provides over temperature protection due to
reduced airflow, such as a dirty filter.
Unitary Products Group
Auxiliary Limit Controls
Downflow/horizontal units have a single limit switch munted
on the blower assembly. This is a manual reset control and
gives high temperature protection in the event of a blower
motor failure.
START-UP AND ADJUSTMENTS
The initial start-up of the furnace requires the following addi-
tional procedures:
1.
When the gas supply is initially connected to the furnace,
the gas piping may be full of air. In order to purge this air,
it is recommended that the ground union be loosened
until the odor of gas is detected. When gas is detected,
immediately retighten the union and check for leaks.
Allow five minutes for any gas to dissipate before con-
tinuing with the start-up procedure.
Be sure proper ventilation is available to dilute and
carry away any vented gas.
Perform the following procedures only after the
condensate trap has been properly piped to a
drain connection using the procedure in this
instruction.
2.
The condensate trap must be filled with water before put-
ting the furnace into operation. The recommended pro-
cedure is as follows:
a.
Disconnect the condensate drain hose from the
induced draft blower discharge.
b.
Elevate this hose and fill with water using a funnel.
c.
Replace the condensate drain hose and clamps.
NOTE : If this procedure is not followed, the unit may not prop-
erly drain on initial start up.
3.
All electrical connections made in the field and in the fac-
tory should be checked for proper tightness.
IGNITION SYSTEM SEQUENCE
1.
Turn the gas supply ON at external valve and main gas
valve.
2.
Set the thermostat above room temperature to call for
heat.
650.75-N4U
27
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