Operator`s manual

Operator's Manual: Models CB-1400, CB-1800, and CB-2800
A-14
Fan Limit Control
Understanding the Operation of the Fan Limit Control
The fan limit control senses air temperature within the furnace cabinet. This control contains two
switches: the limit switch and the fan switch.
Fan Switch: The fan switch is normally open and provides power to the fan (or blower). When the fan
limit control senses "Fan On" temperature, the fan switch closes and starts the fan (or blower). When
the wall thermostat is satisfied and the burner shuts off, the fan continues to run until the fan limit
control senses the "Fan Off" temperature. At this temperature, the fan switch opens and shuts off the fan
(or blower).
NOTE: The fan limit control has a white fan switch button. Make sure the white button is pulled OUT
for automatic (normal) operation. When the button is pushed in (manual setting), the fan will run
continuously.
Limit Switch: The limit switch is normally
closed and provides power to the oil primary
control on the burner. If the fan limit control
senses 200 degrees F, the limit switch opens
and shuts off power to the oil primary control
and the burner stops running. The fan (or
blower) continues to run. Once the fan limit
control senses 170 degrees F, the limit switch
automatically resets and restarts the burner.
NOTE: It is very important to avoid cycling
the burner on hi limit as described above. If
the hi limit activates, immediately check and
readjust burner settings.
ATTENTION: DO NOT change the fan limit
settings from the specified settings, or severe
damage to the furnace cabinet may occur.
To Set Pointers on the Fan Limit Dial
1. Turn OFF main power to the furnace.
2. Remove the fan limit control cover.
3. While holding the dial securely in place
with your thumb, move the pointer to
the desired setting.
ATTENTION: DO NOT rotate the dial when
setting the pointers. This severely damages the
control.
Fan Limit Control Settings: CB-1800 / CB-2800
Fan Off: 110
Fan On: 140
Limit: 200
Fan Limit Control Settings: CB-1400
Fan Off: 100
Fan On: 120
Limit: 200
FIGURE A7 - Fan Limit Control Components
5O
1OO 2OO
25O
15O
5O
1OO 2OO
25O
15O
LIMIT
(RIGHT POINTER)
FAN OFF
(LEFT POINTER)
FAN ON
(MIDDLE POINTER)
CAUTION
DO NOT ROTATE
HOLD DIAL WHEN SETTING
POINTERS
CAUTION
DO NOT ROTATE
HOLD DIAL WHEN SETTING
POINTERS
TO RELEASE
WIRE, PUSH
SCREWDRIVER
IN AND PULL
WIRE OUT
BLACK WIRE
BRASS
JUMPER
FAN LIMIT
LOAD
LOAD
LINE LINE
ORANGE WIRE (CONNECT TO FAN)
RED WIRE (CONNECT TO LIMIT)
50
100
150
200
250
50
100
150
200
250