L.B. White AD100 Owner's Manual page 17

1. Remove the following in the order given:
-- Gas hose and sediment trap from the inlet of gas
the control valve.
-- AD250: Plastic bushing at gas inlet hole. See Fig.
16.
-- Two screws at the inlet of the gas control valve
securing the valve to its mounting bracket or to
the case. See Fig. 16.
-- Bolt with washer securing the manifold to the
burner and base. See Fig. 17.
2. Lift and pivot the gas valve with manifold as needed
so burner orifice clears the burner. See Fig. 18.
3. Replace components as needed.
FIG. 16
SCREWS AT VALVE INLET
The control sends and receives voltages to operate or verify
operation of components. Refer to the following and Fig. 19 to
understand the ignition control's terminal designators if doing
voltage checks on the control.
L1: 220 VAC to control from power supply
IND: 220 VAC from control to fan motor
LED: Connection for control's diagnostic light wiring
harness
MV: 24 VAC from control to high limit switch and then to
gas control valve.
PS2: 24 VAC from air proving switch back to control
PS1: 24 VAC from control to air proving switch
W: 24 VAC from transformer to control (without
this voltage the ignition control will not function)
FS: Microamperage from control to flame sensor for
proving burner flame
R: No terminal
X: No terminal
C/COM: Control and burner ground
Located in the control box, the transformer reduces
220 VAC to 24 VAC for operation of the the ignition
control. Without 24 VAC from the transformer, the red
diagnostic light will not be on and the ignition control
will not function.
GAS CONTROL VALVE AND BURNER ORIFICE
FIG. 17
FIG. 18
VALVE
ORIFICE
Also refer to "Operation Sequence" within this manual as
needed to understand operation of the ignition control during
a call for heat.
FIG. 19
FIG. 20
BOLT AND WASHER
(UNDERSIDE OF BASE)
IGNITION CONTROL
TRANSFORMER
17