circulating blower remain energized. If the thermostat signals a requirement for second−stage heat (W2), the ignition control initiates high heat operation.
When a signal for second stage heat is received by the ignition control, the control energizes the second−stage gas valve and high−speed combustion air inducer until the demand is satisfied.
If a first−stage heat demand continues after the second−stage heat demand has been satisfied, the ignition control immediately de−energizes the second−stage gas valve. The combustion air inducer is held in high speed operation for an additional 1 second after the second−stage gas valve is de−energized. First−stage heat operation (first−stage gas valve and low−speed combustion air inducer) continues until heating demand is satisfied.
When the heating demand is satisfied, the control immediately de−energizes the gas valve. The combustion air inducer remains energized for a 30−second post−purge period. The circulating air blower operates for 90 seconds after the gas valve is de−energized.
Blower Delay − Heating
In the heating mode, the circulating air blower operation is
delayed for 30 seconds after the flame is established. The blower continues to operate for 90 seconds after the gas valve is de−energized.
NOTE − With the proper thermostat and subbase, continuous blower operation is possible by closing the R to G circuit.
Unit Controls
Blower Control (A54)
15GCSX units are equipped with a variable speed motor which is controlled by a blower control. Blower control settings and operation are given on page 12.
Ignition Control (A3)
The 15GCSX unit includes an ignition control which controls the combustion air inducer, gas valve and spark electrode. It receives signals from the main and auxiliary limit switches, the roll out switch, the pressure switch and the flame sensor. LED codes and flash rates are given on page 17. The ignition control is shown in figure 14.
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