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manual abstract
For the second attempt to ignite gas within the same call for heat, the control increases the ignitor temperature to the value it was on the third previous successful ignition. After ignition is successful, the control sets the ignition temperature at this value for the next 255 calls for heat, after which the control repeats the adaptive algorithm. The control is constantly making adjustments to the ignitor temperature to compensate for changes in the line voltage. The 80 VAC Silicon Nitride ignitor manufactured by White-Rodgers must be used. These ignitors are specially designed to operate with the 50A62’s adaptive ignition routine to ensure the most efficient ignitor temperature. At the end of the ignitor warm-up time, both valves in the 36E manifold gas valve are opened. Flame must be detected within 4 seconds. If flame is detected, the delay-to-fan-on period begins. After the delay-to-fan-on period ends, the circulator fan is energized at heat speed. If there is an optional electronic air cleaner on the system, the electronic air cleaner and the humidifier are energized. When the thermostat is satisfied, the gas valve is de-energized. After proof of flame loss, the inducer blower remains energized to purge the system for 5 seconds. When the purge is complete, the inducer blower and humidifier are de-energized and the delay-to-fan-off period begins. After the delay-to-fanoff period ends, the circulator fan and electronic air cleaner are de-energized. If flame is not detected, both valves are de-energized, the ignitor is turned off, and the 50A62 control goes into the “retry” sequence. The “retry” sequence provides a 15second wait following an unsuccessful ignition attempt (flame not detected). After this wait, the ignition sequence is restarted. If this ignition attempt is unsuccessful, one more retry will be made before the control goes into system lockout. If flame is detected, then lost, the 50A62 control will repeat the initial ignition sequence for a total of three “recycles”. After three unsuccessful “recycle” attempts, the control will go into system lockout. If flame is established for more than 10 seconds after ignition, the 50A62 controller will clear the ignition attempt (or retry) counter. If flame is lost after 10 seconds, it will restart the ignition sequence. This can occur a maximum of five times before system lockout. During burner operation, a momentary loss of power of 50 milliseconds or longer will de-energize the main gas valve. When power is restored, the gas valve will remain de-energized and a restart of the ignition sequence will begin immediately. A momentary loss of gas supply, flame blowout, or a shorted or open condition in the flame probe circuit will be sensed within 2 seconds. The gas valve will de-energize and the control will restart the ignition sequence. Recycles will begin and the burner will operate normally if the gas supply returns, or the fault condition is corrected, before the last ignition attempt. Otherwise, the control will go into system lockout. If the control has gone into system lockout, it may be possible to reset the control by a momentary power interruption of one second or longer. Refer to PRECAUTIONARY, SYSTEM LOCKOUT, AND DIAGNOSTIC FEATURES. COOL MODE In a typical system, a call for cool is initiated by closing the thermostat contacts. This starts the 50A62 control’s cooling sequence. The compressor is energized and the cool mode delay-to-fan-on period begins. After the delay-tofan- on period ends, the circulator fan is energized at cool speed. The electronic air cleaner (optional) is also energized. After the thermostat is satisfied, the compressor is de-energized and the cool mode delay-to-fan-off period begins. After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner (optional) are de-energized. MANUAL FAN ON MODE If the thermostat fan switch is moved to the ON position, the circulator fan (fan speed) and optional electronic air cleaner are energized. When the fan switch is returned to the AUTO position, the circulator fan and electronic air cleaner (optional) are de-energized. PRECAUTIONARY, SYSTEM LOCKOUT, AND DIAGNOSTIC FEATURES PRECAUTIONARY FEATURES The following precautionary features are built into the 50A62 control. 1. If, at any time, the flame rollout sensor opens, the gas valve and ignitor are de-energized. 2. If, at any time, flame is sensed when the gas valve is de-energized, the heat circulator blower and inducer fan are energized and the ignition sequence will go into system lock out. The heat circulator and inducer will remain on as long as flame is detected. If flame is no longer detected, the inducer will turn off in 5 seconds and the circulator will turn off using the maximum heat off delay. 3. If, at any time, the flame rollout switch opens, the heat circulator blower and inducer fan are energized and the ignition sequence will go into system lock out. The inducer will remain energized for 5 seco...