•120 VAC is sent from terminal 1 of connector X13 on the Control Board (A10) to the Generator Pump (M4).
•As the water level drops below the probes the fill solenoid (Y3) will energize. This rocking of the water will help flush scale from the generator.
•Then the pump will be energized again
•When the condensate box is heated to 140 degrees F at the B3probe, 120 VAC is sent from terminal 5 of connector X12 to the condenser valve (Y1) until the temperature drops.,
bThe display will show the set temperature and set time.
cThe Control Board (A10) will check the water level by looking for a ground at terminals 1 and 2 on connector X15. These are connected to the high and low probes (B1) in the steam generator.
•If the ground is not found 120 VAC is sent from terminal 7 on connector X12 on the Control Board (A10) to the fill solenoid (Y3)
•The fill solenoid opens and the generator is filled until both probes are grounded.
◊If the top probe becomes ungrounded for more that 5 seconds the fill solenoid (Y3) will energize.
◊If the bottom probe becomes ungrounded the combi will fill immediately and the combi will not heat
dWhen the terminal 2 on connector X15 is grounded, the Control Board (A10) transmits and receives a signal from terminals 5,6,7 and 8 on connector X10 to terminals 3,4,5 and 6 of connector X28 on the Gas Board (A20)
•The Gas Board (A20) begins the steam generator heat circuit
◊A signal is sent from terminal 8 of connector X24 to terminal 4 of connector X2 on the Steam Power Burner and Fan Control (U21) selecting the set speed of the combustion blower.
(a)When this speed is attained the signal is sent from terminal 2 of connector X2 on the Steam Power Burner and Fan Control (U21) to terminal 9 of connector X24 on the Gas Board (A20)
◊A request for heat is sent from terminal 3 of connector X21 on the Gas Board (A20) to terminal 10 on connector X1 on the Steam Burner Control Module (N21)
(a)24 VAC is sent from terminal 2 of connector X2 on the Steam Burner Control Module (N21) to the hot surface igniter (R20).
(b)The gas valve is energized allowing gas and air into the burner chamber to be ignited by the hot surface igniter.
(c)The Steam Burner Control Module (N21) senses at least 1.5 micro amps DC from the flame sensor (P1) at terminal 3 of connector X2 and sends a signal from terminal 2 of connector X1 to terminal 11 of connector X25 on the Gas Board (A20)
•The steam generator heat circuit continues until 190 degrees F is detected from the Steam Generator probe (B4) at terminals 1 and 2 of connector X17 on the Control Board (A10)
4With the combi in the steam mode with time on the timer, the door closed and the start switch is depressed
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