L.B. White AD100, Owner'S Manual

Page: 16 / 64

This brood heater uses a high limit heat switch for the
purpose of over heat protection. It is connected between the
ignition control and the gas control valve.
The switch has normally closed contacts. If an overheat
condition occurs, the switch contacts will open, thereby
opening the circuit to the gas control valve.
Model AD060/AD100/AD250: The high limit switch is located
on the heat chamber, See Fig. 13 a and 13b.
ModelAD325: The high limit switch is located on the fan
housing side panel at the motor end of the heater. See Fig.
14 a and 14 b.
The high limit switch should be tested a minimum of once per
year when the heater is given a thorough cleaning.
1. Remove the switch. Holding the switch by one of its
mounting legs, apply a small flame only to the sensing
portion on the back of the switch. See Fig. 15. Do not
melt the plastic housing of the switch when
conducting this test.
2. 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.
3. Allow the switch cool down for about a minute before
firmly pressing the reset button on the switch.
4. Check for electrical continuity across the switch
terminals to make sure the contacts have closed.
5. Reinstall the switch back into the brood heater.
Reconnect the brood heater to its electrical supply.
Start the brood heater and check for proper operation.
FIG. 15
MANUAL RESET HIGH LIMIT SWITCH
WARNING
Fire Hazard
■
Do not operate the brood heater with the high limit
switch bypassed.
■
Operating the brood heater a bypassed high limit
switch may lead to overheating, possibly resulting in a
fire, with subsequent damage to the brood heater,
building damage, or loss of livestock.
RESET BUTTON
SENSING
SURFACE
TERMINAL
FLAME
MOUNTING
LEG
HIGH LIMIT SWITCH
(AD100/AD250)
16
HIGH LIMIT SWITCH
(AD060)
REMOVE COVER
SWITCH
(AD325)
FIG. 14a FIG. 14b
FIG. 13a FIG. 13b