FIG. 15 - PROPER FLAME ADJUSTMENT
3.To increase the gas pressure, turn the adjusting screw clockwise.
NOTE: The correct manifold pressure for these furnaces is 3.65 IWG ± 0.3.
PILOT CHECKOUT
Reverse the above procedure to replace the assemblies. Make sure that burners are level and seat at the rear of the heat exchanger.
BURNER AIR SHUTTER ADJUSTMENT
Adjust burner shutters so no yellow flame is observed in the heat exchanger tubes.
CHECKING SUPPLY AIR CFM
The RPM of the supply air blower will depend on the required CFM, the unit accessories or options and the static resistances of both the supply and the return air duct systems. With this information, the RPM for the supply air blower and the motor pulley adjustment (turns open) can be determined from the Blower Performance Data Table.
A high speed drive accessory 1LD0435 (containing a smaller blower pulley and shorter belts) is available for applications requiring the supply air blower to produce higher CFM’s and/or higher static pressures. Refer to the Blower Motor and Drive Data Table.
Note the following:
The pilot flame should envelope the end of the flame sensor.Refer to Proper Flame Adjustment figure. 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
1.Remove the 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
3.Remove the gas piping closure panel.
4.Disconnect wiring to the gas valves and spark ignitors. Remove the
Burners are now accessible for service.
FIG. 16 - TYPICAL FLAME APPEARANCE
FIG.17 - BELT ADJUSTMENT
1.The supply air CFM must be within the limitations shown in Unit Application DataTable.
2.Pulleys can be adjusted in half turn increments.
3.The tension on the belts should be adjusted as shown in the belt adjustment figure below.
Start the supply air blower motor. Adjust the resistances in both the supply and the return air duct systems to balance the air distribution throughout the conditioned space. The job specifications may require that this balancing be done by someone other than the equipment installer.
To check the supply air CFM after the initial balancing has been completed:
1.Remove the two 5/16" dot plugs from the blower motor and the filter access panels.
18 | Unitary Products Group |
