OPERATING INSTRUCTIONS
CAUTION: This furnace is equipped with an intermittent pilot
and automatic re-ignition system. DO NOT attempt
to manually light the pilot.
TO LIGHT PILOT AND MAIN BURNERS:
1. Turn “off” electric power to unit.
2. Turn room thermostat to lowest setting.
3. Turn gas valve knob to “on” position.
4. Turn “on” electric power to unit.
5. Set room thermostat to desired temperature.
(If thermostat “set” temperature is above room temperature,
pilot burner ignition will occur and, after an interval to prove
pilot flame, main burners will ignite).
TO SHUT DOWN:
1. Turn “off” electric power to unit.
2. Depress knob of gas valve while turning to “off” position.
POST-START CHECK LIST (GAS)
After the entire control circuit has been energized and the
heating section is operating, make the following checks:
1. Check for gas leaks in the unit piping as well as the supply
piping.
2. Check for correct manifold gas pressures. See “Checking
Gas Input”.
3. Check the supply gas pressure. It must be within the limits
shown on rating nameplate. Supply pressure should be
checked with all gas appliances in the building at full fire. At
no time should the standby gas line pressure exceed 13",
nor the operating pressure drop below 5.3" for natural gas
units. If gas pressure is outside these limits, contact the local
gas utility for corrective action.
MANIFOLD GAS PRESSURE ADJUSTMENT
Small adjustments to the high-fire gas flow may be made by
turning the pressure regulator adjusting screw on the automatic
gas valve.
Adjust as follows:
1. Remove the cap on the regulator. It’s located next to the
push-on electrical terminals.
2. To decrease the gas pressure, turn the adjusting screw
coun-
terclockwise.
3. To increase the gas pressure, turn the adjusting screw
clock-
wise.
NOTE: The correct manifold pressure for these furnaces is 3.5
IWG
±
0.3.
PILOT CHECKOUT
The pilot flame should envelope the end of the flame sensor as
shown in Proper Flame Adjustment . To adjust pilot flame, (1)
remove pilot adjustment cover screw, (2) increase or decrease
the clearance for air to the desired level, (3) be sure to replace
cover screw after adjustment to prevent possible gas leakage.
Put the system into operation and observe through complete
cycle to be sure all controls function properly.
BURNER INSTRUCTIONS
To check or change burners, pilot or orifices, CLOSE MAIN
MANUAL SHUT-OFF VALVE AND SHUT OFF ALL POWER TO
THE UNIT.
1. Remove the two screws holding either end of the manifold to
the burner supports.
2. Open the union fitting in the gas supply line just upstream of
the unit gas valve and downstream from the main manual
shut-off valve.
3. Remove the gas piping patch plate.
4. Disconnect wiring to the gas valve and spark ignitor. Remove
the manifold-burner gas valve assembly by lifting up and
pulling back.
Burners are now accessible for service.
Reverse the above procedure to replace the assembly. Make
sure that burners are level and seat at the rear of the heat
exchanger.
START-UP
ON-OFF CONTROL
HIGH FIRE ADJ.
(UNDER SCREW)
PILOT ADJ.
(UNDER SCREW)
FIG. 12 - TYPICAL GAS VALVE
1/8" GAP BETWEEN CARRY-OVER
TUBE AND FLAME SENSOR BULB
CARRY-OVER TUBE
FLAME SENSOR BULB
BURNER ASSEMBLY BRACKET
FIG. 13 - PROPER FLAME ADJUSTMENT
530.18-N10Y
Unitary Products Group
15
