York DF078 Series User's, Maintenance And Service Information Manual

Contents

035-19047-002-A-1103Unitary Products Group 3INPUTThe correct heat capacity of the furnace is regulated bythe burner orifices and the gas pressure. The properorifices are furnished but the gas pressure regulatormust be adjusted by the installer or gas utility servicetechnician.OPERATING INSTRUCTIONSTO SHUT DOWN THE FURNACE:1. Close the main gas shutoff valve(s).2. Turn off the electric power supply.TO LIGHT THE FURNACE:1. Do not attempt to light manually.2. Open the main gas shutoff valve(s).3. Adjust the set point of the room thermostat abovethe temperature in the space.4. Turn on the electric power supply.5. The draft fan will operate. After an adequate purgetime, the electric spark igniter will light the burners.6. The burners will extinguish and relight automati-cally upon the demand of the room thermostat.VENT SAFETY SYSTEM:This gas furnace is equipped with a manual reset hightemperature sensor or rollout switch which in theunlikely event of a sustained main burner flame rolloutwill shut off the flow of gas by closing the main gasvalve. The ignition modules will also be disabled, pre-venting the flow of gas to the valve. The switch islocated inside the gas heat access panel above theburner inlet. Flame rollout can be caused by blockageof the power vent system, improper gas pressure oradjustment. If this event occurs the furnace will notoperate properly. The gas supply to the furnace shouldbe shut off and no attempt should be made to place thefurnace in operation. The system should be inspectedby a qualified service technician. Refer to Figure 2 for atypical installation.100% SHUT OFF:The ignition modules are designed for 100% shut-off. Ifthe furnace fails to ignite after three ignition attempts,the flow of gas will be shut off and the ignition modulewill lock out. The module can be reset by:A. Turning the system switch on the room thermostatto the “OFF” position and back to the “HEAT” posi-tion.B. Decreasing the set point of the room thermostatbelow the temperature in the conditioned spaceand returning it to its original setting.C. Opening and closing the unit's main disconnectswitch.If the furnace continues to lock out, a qualified servicetechnician should be called to determine the cause ofthe problem.FIGURE 2- TYPICAL INSTALLATIONELECTRICAL SHOCK, FIRE OR EXPLOSION HAZARDFailure to follow safety warnings exactly could resultin dangerous operation, serious injury, death or prop-erty damage.Improper servicing could result in dangerous opera-tion, serious injury, death or property damage.• Before servicing, disconnect all electrical powerto furnace.• When servicing controls, label all wires prior todisconnecting. Reconnect wires correctly.• Verify proper operation after servicing.Prior to any of the following maintenance procedures,shut off all power to the unit to avoid personal injury.MainGasShut-offValveieldInstalled(MountedExternally)