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Page 8 of 13 507295-02Cmrcool.com
Figure 6. Typical Wiring Connections
Red
Blue
Yellow
White
Green
75
Heating Start-Up
For Your Safety, Read Before Lighting
Furnace is equipped with a direct ignition control. Do
not attempt to manually light the burners.
CAUTION
Pre-Start Checklist
Complete the following checks before starting the unit:
1. Check the type of gas being supplied. Be sure it is the
same as listed on the unit nameplate.
2. Make sure that the vent cover has been properly
installed.
To Light Main Burners
1. Turn off electrical power to unit.
2. Turn the thermostat to lowest setting.
3. Slide the gas valve switch to the “ON” position (see
Figure 7).
4. Turn on electrical power to the unit.
5. Set the room thermostat to the desired temperature.
(If the thermostat “set” temperature is above room
temperature after the pre-purge time expires, main
burners will light.)
To Shut Down Main Burners
1. Turn off electrical power to unit.
2. Slide the gas valve switch to the “OFF” position (see
Figure 7).
Regulator
Adjustment
Figure 7. Gas Valve
Post-Start Checklist
After the entire control circuit has been energized and the
heating section is operating, make the following checks:
1. Check for gas leaks, using soapy solution, in the unit
piping as well as the supply piping.
2. Check for correct manifold gas pressures (see Manifold
Gas Pressure Adjustment Regulator sections).
3. Check the supply gas pressure. It must be within the
limits shown on the rating plate. Supply pressure
should be checked with all gas appliances in the
pressure exceed 13” w.c., nor the operation pressure
drop below 5” w.c. for natural gas units or 11” w.c. for
propane gas. If gas pressure is outside these limits,
contact the gas supplier for corrective action.
4.
rating plate.
Manifold Gas Pressure Adjustment Regulator – Natural
Gas
For purpose of input adjustment, the minimum permissible
gas supply pressure is 5” w.c. for natural gas.
Gas input must never exceed the input capacity shown on
the rating plate. The furnace is equipped for natural gas
rated inputs with manifold pressure of 3.5” w.c.
The manifold pressure can be measured by shutting off
the gas, removing the pipe plug in the downstream side
of the gas valve, and connecting a water manometer
or gauge.
manifold pressure vary more than 0.3” w.c. from the
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