282911-YIM-B-0807
16
Unitary Products Group
2.
Turn off all electric power to the appliance if service is to
be performed.
3.
Remove the control access panel.
4.
Turn the gas valve switch to the OFF position. DO NOT
FORCE.
5.
Replace the control access panel.
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 sup-
ply piping.
2.
Check for correct manifold gas pressures. See Checking
Gas Input.
3.
Check the supply gas pressure. It must be within the lim-
its 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 10.5", nor the operating pressure drop below
4.5" 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 gas flow may be made by turning
the pressure regulator adjusting screw on the automatic gas
valve. Refer to Figure 10.
Adjust as follows:
1.
Remove the cap from the valve body. See Figure 10 for
location.
2.
To decrease the gas pressure, turn the adjusting screw
counterclockwise.
3.
To increase the gas pressure, turn the adjusting screw
clockwise.
NOTE:
The correct manifold pressure for natural gas fur-
naces is 3.5 IWG. The correct manifold pressure for
propane (LP) is 10.0 IWG.
BURNER INSTRUCTIONS
To check or change the burners, CLOSE THE MAIN MAN-
UAL SHUT-OFF VALVE AND SHUT OFF ALL POWER TO
THE UNIT.
1.
Remove the two (2) #8 screws holding each burner in
place.
2.
Remove the burner assembly from the manifold assem-
bly by moving the burner assembly forward, turn at an
angle and pull back.
3.
Burners are now accessible for service.
PILOT INSTRUCTIONS
To check, adjust or remove the pilot assembly, CLOSE THE
MAIN MANUAL SHUT-OFF VALVE AND SHUT OFF ALL
POWER TO THE UNIT.
The pilot flame should envelope 3/8 inch of the end of the
flame sensor and not contain any yellow color, see Figure 12.
FIGURE 10 - GAS VALVE - FRONT
Electrical
Connection
Manual
Gas Switch
Pilot
Adjustment
(Remove Cap)
Manifold
Pressure
Adjustment
(Remove Cap)
Pilot Gas
Connection
Manifold
Pressure Tap
½
NPT
(Outlet)
FIGURE 11 - GAS VALVE - REAR
Line
Pressure
Tap
½
NPT
(Inlet)
