Lanair DHI 300 - Manual (Page 23)

Section 9 - Controls
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• 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.
• 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 two (2) minute automatic re-start feature.
• 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.
• Barometric Draft Control
The Barometric Draft Control automatically maintains a pre-set chimney draft, and is locat-
ed in the chimney connector.
• 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.
Section 12 - Flame Adjustment
QUESTIONS?... Contact Customer Service at 1-800-753-1601 M-F 8:00 am- 4:15 pm CST
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Lift the inspection port cover on the front of the combustion chamber to observe the flame.
The flame tips should extend 3/4 of the way into the combustion chamber. When the unit is
adjusted properly the ash inside the chamber will be white to off white.
Flame tips touching the target brick (end of the chamber) will cause combustion chamber
damage. This condition may be caused by a worn nozzle, or excess burner fuel pressure.
When this condition exists, the ash in the chamber will
be brown to black.
Flame Adjustment - Visual
Flame is over-fired (Fig. 11).
• Dark yellow, to orange in color.
• The flame is hitting the walls, filling the chamber
with a smokey flame. Correct immediately or
chamber may be damaged.
• Decrease fuel pressure, and adjust combustion
air baffle. Air pressure may also need to be
adjusted.
Problem: Too large of a flame, dark yellow in color.
1. Too much fuel pressure.
2. Not enough combustion air.
3. Not enough atomizing air pressure.
4. Ash inside the chamber is dark brown to sooty
black in color.
Flame is under-fired (Fig. 12).
• The flame is like a blow torch.
• Light yellow, to white in color.
• Flame is too short.
• Check to see if pre-heater block is hot.
• Check air PSI, it may be too high. Adjust in 1 LB.
increments.
• Oil pressure and the combustion air baffle may
need adjustment.
BAD FLAME
The flame is too big, creating an over-
fire condition
BAD FLAME
The flame is too short
GOOD FLAME
The flame length is approximately 3/4
of the chamber
Figure 11
Figure 12
Figure 13
NOTE: ALWAYS WEAR EYE, FACE AND BREATHING PROTECTION AND
PROTECTIVE CLOTHING WHEN INSPECTING OR ADJUSTING FLAME.
!