NORMAL SEQUENCES OF OPERATION
HEATING
This unit is equipped with an ignition control that automatically lights the main burner. DO NOT attempt to light the main burners by any other method.
1.Thermostat calls for low or high stage heating.
2.Induced draft blower energizes for
3.The spark igniter and low and high stage gas valve are energized for 7 seconds. NOTE: The igniter produces a very intense electrical spark that ignites the gas.
4.Main burners light and control detects presence of flame.
5.If the call is for low stage heat, the induced draft blower switches to low speed and the high stage gas valve closes 5 seconds after the main burners light. If call is for high stage heat, induced draft blower remains at high speed and high stage gas valve remains open.
NOTE: If a single stage thermostat is used, the control will step to low stage after the main burners light and remain at low stage for 5 or 10 minutes, depending on jumper position. If the call for HEAT remains after the transition delay time expires, the control will transition from low stage to high stage.
6.The
7.The unit delivers heat to the conditioned space until the thermostat is satisfied.
8.Gas valve(s)
9.Induced draft blower remains at low speed (or switches from high to low if operating at high stage heat) for the 30- second post purge.
10.Ignition control begins timing the HEAT FAN OFF delay. There is an adjustable HEAT FAN OFF delay of approximately 90/120/150/180 seconds (factory set at 150). If the unit is operating at high stage when the call for heat is removed, the blower will operate for 30 seconds at high heat speed then switch to low heat speed for the remainder of the selected HEAT FAN OFF delay.
NOTE: After the HEAT FAN OFF delay time has elapsed, the blower will
COOLING
1.Thermostat calls for low or high stage cooling.
2.If the thermostat call is for low stage cooling, the compressor and outdoor fan are energized at low stage. If the thermostat call is for high stage cooling, the compressor and outdoor fan are energized at high stage.
3.The indoor blower will energize approximately 6 seconds later.
4.The unit delivers cooling to the conditioned space until the thermostat is satisfied.
5.The compressor and outdoor fan will be
6.The indoor blower continues to run at low cool speed for approximately 60 seconds after the thermostat is satisfied. This allows additional cooling from the indoor coil to be transferred to the conditioned space. Then, the indoor blower is
NOTE: A
FAN ONLY
1.Thermostat calls for FAN ONLY by energizing “G”.
2.The indoor blower is immediately energized at the low heat speed.
3.The indoor blower is immediately
STARTUP, ADJUSTMENTS, AND CHECKS
HEATING STARTUP
This unit is equipped with an electronic ignition device to automatically light the main burners. It also has a power vent blower to exhaust combustion products.
On new installations, or if a major component has been replaced, the operation of the unit must be checked.
Check unit operation as outlined in the following instructions. If any sparking, odors, or unusual sounds are encountered, shut off electrical power and check for wiring errors, or obstructions in or near the blower motors. Duct covers must be removed before operating unit.
Heat Anticipator Setting
Set the heat anticipator on the room thermostat to 0.4 amps to obtain the proper number of heating cycles per hour and to prevent the room temperature from overshooting the room thermostat setting.
Rollout Protection Control
The rollout protection device opens, cutting power to the gas valve, if the flames from the burners are not properly drawn into the heat exchanger. The rollout protection device is located on the burner bracket. The reason for elevated temperatures at the control must be determined and repaired prior to resetting this manual reset control.
Rollout Protection |
Rollout Protection on Burner Bracket
Secondary Limit Control
The secondary limit control is located on the top of the blower scroll assembly. This control opens when elevated temperatures are sensed. Elevated temperatures at the control are normally caused by blower failure. The reason for the opening should be determined and repaired prior to resetting.
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