X. Heating Sequence of Operations PGB & PGC)
Normal Sequence of Operation - Heating
See Figure 12
1.Thermostat calls for heat. The combustion blower is immediately energized.
2.The pressure switch contacts transfer.
3.The ignitor is energized and allowed to preheat for 38 seconds.
4.The gas valve is energized delivering gas to the burners and starting combustion.
5.The control checks the signal from the flame sen- sor. Gas flow will continue only if a proper signal is present within seven seconds after the gas valve opens. As soon as flame is proven, the ignitor is de- energized.
6.The unit will continue to fire while the helical fan control heats up. The fan control will start the main circulating air blower approximately 75 seconds af- ter the gas valve opens (this time may vary depend- ing on the control setting).
7.The furnace will deliver heat to the conditioned space until the thermostat is satisfied.
8.The gas valve and combustion blower will be de- energized when the thermostat opens.
9.There is a 90 second delay (approximate) before the main air blower stops. This allows any additional heat in the heat exchanger to be transferred to the conditioned space.
XI. Cooling Sequence of Operations
PGB Normal Sequence of Operations - Cooling
See Figure 13A
1.Thermostat calls for cooling. The compressor and outdoor fan are energized.
2.Approximately 15 seconds later, the fan time delay relay closes. The indoor fan now begins operation.
3.The unit will deliver cooling to the conditioned space until the thermostat is satisfied.
4.The compressor and outdoor fan will be
5.Refrigerant will continue to flow through the capil- lary tube (sizes 24 to 42) until the high and low side pressures are approximately equal. Refrigerant will continue to flow through the thermal expansion valve until the high and low side pressures are approxi- mately 50 PSI apart.
6.The indoor fan continues to run for approximately 45 seconds after the thermostat is satisfied. This allows additional cooling from the indoor coil to be transferred to the conditioned space.
PGC Normal Sequence of Operations - Cooling
See Figure 13B
1.Thermostat calls for cooling. The compressor, in- door fan, and outdoor fan are energized.
2.Approximately 30 seconds later, the indoor fan ramps up to full speed.
3.The unit will deliver cooling to the conditioned space until the thermostat is satisfied.
4.The compressor and outdoor fan will be
5.Refrigerant will continue to flow through the capil- lary tube (sizes 24 to 42) until the high and low side pressures are approximately equal. For the PGC48, 60 and PGB58 refrigerant will continue to flow through the thermal expansion valve until the high and low side pressures are approximately 50 PSI apart.
6.The indoor fan continues to run for approximately 30 seconds after the thermostat is satisfied. This allows additional cooling from the indoor coil to be transferred to the conditioned space. Then, the in- door fan ramps down in 30 seconds to the OFF con- dition.
XIl. Startup and Adjustment
Heating Startup
General Information
This furnace is equipped with an electronic ignition de- vice which lights the burners. It also has a power vent blower to exhaust combustion products.
On new installations, or if a major part such as the gas valve, pressure switch or fan/limit control has been re- placed, the operation of the furnace must be checked.
Check furnace operation as outlined in the following in- structions. If any sparking, odors, or unusual noises are encountered, shut off electrical power and recheck for wiring errors, or obstructions in or near the blower mo- tors. Various shipping materials must be removed be- fore the indoor and outdoor fans can be operated.
Heat Anticipator Setting
The heat anticipator in the room thermostat must be correctly adjusted to obtain the proper number of heat- ing cycles per hour and to prevent the room tempera- ture from
Roll-out Protection Control
If the flames from the burners are not properly drawn into the heat exchanger, a protection device will open, causing the gas valve to close. The protection device is located on the manifold assembly (Figure 14).
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