Lanair HI140 - Manual (Page 23)

SECTION 12 FURNACE CONTROLS AND
OPERATION
12.1 Room Thermostat:
The room thermostat automatically controls the on/off operation of the
heater according to the setting of the desired room temperature.
The thermostat works in conjunction with the oil primary safety control.
12.2 Oil Primary Safety Control/Cad Cell:
The oil primary control is mounted on top of the burner’s electrical box.
When the thermostat calls for heat the oil primary control starts the burner
by switching on the air solenoid valve, ignition transformer, combustion air
blower, and the fuel pump. The oil primary control works in conjunction with
the cadium sulfide cell (cad cell). The cad cell is mounted inside the burner
cover, and faces the flame. The cad cell monitors the light level inside the
combustion chamber to insure there is a flame present. If there is a loss of
flame the primary control will go into its recycle mode. After 1-2 minutes the
primary control will restart the burner. When this happens if there is a flame
present, the burner will continue to function. If on start up no flame is
established in 30 seconds the primary control will lock out.
CAUTION:
Do not press the reset button more than twice. If the burner fails to
start refer to Section 17 Trouble Shooting.
12.3 Fan/Limit Control
The fan/limit control performs 3 functions. The fan/limit control monitors the
temperature of the air inside the cabinet. When the air reaches a set point
(usually 120º F) it will switch on the heater fan. When the temperature in
the cabinet drops below 90º F the fan/limit control will turn the fan off.
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