Air Proving Switch; Thermocouple - L.B.White Guardian AB250 Manual Del Usuario E Instrucciones

20
Guardian LP or Natural Gas Heater
NOTES:
a. Fan wheel to motor mount plate spacing must be
adjusted to the clearance specified below before
tightening the fan wheel to the motor shaft. See
Fig. 16.
b. Make sure that set screw(s) of the fan are on the
flats of motor shaft when tightening.
FIG. 16
MOTOR MOUNT PLATE
MOTOR

Air Proving Switch

The air proving switch must work properly to allow
ignition. It is wired in series to the high limit switch,
which is then in series to the gas control valve. If the
air proving switch contacts do not close on a call for
heat after the fan motor starts, ignition will not occur.
The air proving switch is located on the fan housing
at the motor end of the heater. See Fig. 17
1. Remove the two (2) sheet metal screws holding
the switch with bracket to blower housing.
2. Remove the assembly by turning the switch
so the paddle on the switch arm can be pulled
through the oblong hole on side of fan housing.
FIG. 17
AIR PROVING SWITCH
Owner's Manual • Guardian
FAN WHEEL
CLEARANCE 1/8 in.

Thermocouple

1. Loosen wing screw at pilot assembly. See
Fig. 18.
2. Remove the pilot shield, exposing the pilot
assembly.
3. Loosen the thermocouple's attachement nut
at the pilot bracket. Remove thermocouple
from the pilot assembly. See Fig. 19.
4. Remove the thermouple's lead connector nut
threaded into the gas control valve.
■ The thermocouple is an important safety
device which works directly with the pilot
safety control valve. It should only be
replaced with the thermocouple part number
as given in the parts list.
■ When threading the thermocouple's
connector nut back into the power unit on the
gas control valve, thread the nut in finger tight
and snug it in place with a wrench. DO NOT
OVERTIGHTEN OR USE UNNECESSARY
FORCE ON THE NUT WHEN TIGHTENING.
Doing so will destroy the power unit in the
gas control valve.
FIG. 18
PILOT SHIELD
WING
SCREW