Lanair MX300 - Manual (Page 27)

Section 9 - Controls
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s 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.
s Oil Primary Safety Control/Cad Cell:
The oil primary control is mounted on top of the burner’s electrical box. When the thermo-
stat 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 con-
trol works in conjunction with the cadmium 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 pri-
mary 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 func-
tion. 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 14 - Trouble Shooting.
Burner has a (2) minute automatic restart feature.
s 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. The Fan/Limit Control contains an external slide switch to turn
the axial fan on manual by-passing its automatic function.
The Fan/Limit Control monitors the temperature of the air inside the cabinet. When the
temperature exceeds a fixed set point it switches the burner (Oil Primary Control) off until
the temperature drops to a safe level. The burner will then restart.
“CAUTION” This means the heater has reached its “High Limit”, the cause must be deter-
mined and corrected before further use (over firing the unit is normally what causes this
condition). The Fan/Limit Control is located on the top on the front of the cabinet.
s Barometric Draft Control
The Barometric Draft Control automatically maintains a pre-set chimney draft, and is locat-
ed in the chimney connector.
s Air Filter/Regulator
The Air Filter/Regulator performs two functions: It removes condensation and dirt from the
air. and it controls the amount of air pressure reaching the nozzle and air operated fuel
valve. The Air/Filter Regulator is mounted on the cabinet near the burner.