L.B. White AW250(building controller) - Manual (Page 17)

17
TESTING THE MANUAL RESET HIGH LIMIT SWITCH
WARNING
Fire Hazard
■
Do not operate the heater with the high limit switch
bypassed.
■
Operating the heater a bypass high limit switch may
lead to overheating, possibly resulting in a fire, with
subsequent damage to the heater, building damage, or
loss of livestock.
The high limit switch should be tested a minimum of once
per year when the heater is given a thorough cleaning.
1. Disconnect the heater from its electrical supply.
2. Remove the high limit switch.
3. Holding the switch by one of its mounting legs, apply
a small flame only to the sensing portion on the back
of the switch. Be careful not to melt the plastic
housing of the switch when conducting this test.
4. Within a minute, you should hear a pop coming from
the switch, which indicates the contacts of the switch
have opened. Check for lack of electrical continuity
across the switch terminals to verify contacts have
opened.
5. Allow the switch cool down for about a minute before
firmly pressing the reset button on the switch.
6. Check for electrical continuity across the switch
terminals to make sure the contacts have closed.
7. Reinstall the switch back into the heater. Reconnect
the heater to its electrical supply. Start the heater
and check for proper operation.
FIG. 14
RESET BUTTON
SENSING
SURFACE
TERMINAL
FLAME
MOUNTING
LEG
TO REMOVE CONTROL BOX AND WIRE HARNESS FROM HEATER
1. Disconnect flame sensor lead and high voltage
ignition lead from ignition control and route these
back through the rubber grommet in the back of the
control box.
2. Disconnect all electrical wiring from the ignition
control which exits the back of the control box, and
those same wires from the components or the areas
to which these wires are connected.
3. Remove liquid tight connector nut and sealing washer
on inside of control box. Pull connector with harness
from back of control box.
4. Remove the three (3) screws on each side of the
control panel and remove the control box from the
heater.
FIG. 15
REMOVE 3 SCREWS
(EACH SIDE)
CONTROL
PANEL
NUT, LIQUID TIGHT
WASHER, SEALING
HARNESS
RUBBER GROMMET
WIRE HARNESS
WITH WATER TIGHT
CONNECTOR