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OPERATION SEQUENCE-
G17 SERIES
1- When disconnect is closed, 120V feeds to line voltage
side of the blower control (A15). Door interlock switch
(S51) must be closed for A15 to receive voltage.
2- A15 supplies 120V to transformer (T1).
3- T1 supplies 24VAC to terminal 24" on A15. In turn,
terminal R" of A15 supplies 24VAC to terminal RC"
of the thermostat (S1).
4- When there is a call for heat, W1 of the thermostat enĆ
ergizes W of the blower control with 24VAC.
5- CAB of the blower control energizes the damper motor
(B17) which opens the damper door. When door is in
full open position, damper prove switch (S64) closes.
6- When S64 closes, assuming the flame rollout switch
(S47) and blocked vent shutoff switch (S62) are
closed, 24VAC is supplied to the TH" terminal of the
electronic control (A3).
7- Through the electronic control, the pilot valve P" of
the gas valve opens. The spark electrode ignites the
pilot and the flame sensor senses the pilot.
8- When flame is sensed the main gas valve opens and
supplies the burners with gas.
9- Terminal V" (Valve Sense) of the blower control
senses that the gas valve is energized and initiates a
45 second time delay. At the end of the 45 seconds the
blower, (B3) is energized.
10- When the heat demand has been satisfied, W1 of the
thermostat de-energizes the gas valve and damper
spring closes the damper door. As the damper door
closes, the damper prove switch opens. The blower
runs for a designated period (90-330 sec.) as set by
jumper on blower control.
