Carrier 48TC - Set Heating Setpoint; How to Shut Unit Off; Turn Off Gas and Electrical Supply; Set Thermostat to OFF

Step 10 -- To start unit, set room thermostat/unit controller
heat setpoint to slightly above room temperature. The
induced-draft combustion air fan will start. The RTU gas
valve will open and main burners should ignite within 5
seconds. If the burners do not light, there is a 22-second
delay. Burners will attempt to ignite within 5-seconds. Each
time the burner fails to light, the 22-second time delay is
repeated. If the burner does not light within 15 minutes, the
unit will lockout the gas heat. To reset after a lockout, turn
off the main electrical supply to the unit by switching the
RTU main disconnect to OFF for a minimum of five seconds.
Repeat Steps 1-10. If burners still do not light, call for
service.
Step 11 -- Set the room thermostat/unit controller heating
setpoint to desired temperature setting.
Fig. 11 - Thermostat/Unit Controller
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FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death or property damage.
If the main burners fail to light, or the blower fails to
come on, shut down gas heating section and call your
dealer for service.
TO SHUT UNIT OFF
FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
1. Turn off gas supply by closing the gas line supply
valve. Then, turn off the electrical power supply to
the unit by switching the disconnect to off. Install
lockout tag before servicing or performing main-
tenance.
2. Do not turn off the electrical power to unit without
first turning off the gas supply.
Step 1 -- Set room thermostat/unit controller heat setpoint
to the lowest temperature setting and set the SYSTEM
switch to OFF.
Fig. 12 - Thermostat/Unit Controller
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Step 2 -- Turn off gas supply by closing the gas supply
shut-offvalve (external to RTU unit). See Fig. i for location.
Fig. 13 - Gas Supply Shut Off Valve
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Step 3 -- Turn off the electrical supply to the unit by
switching the RTU main disconnect to off. Then, ensure
personal safety by installing a lockout tag on the disconnect.
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Fig. 14 - RTU Main Disconnect - Electrical Supply
Step 4 -- Remove the compressor access panel. For location
of compressor access panel, see Fig. 5.
Fig. 15 - Compressor Access Panel
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Should overheating occur or the gas supply fail to shut
off, shut off the gas valve in the unit (by moving on/off
switch to off) before shutting off the electrical supply.