507769-05G / 31-5000656
Page 45 of 55
Issue 2223
Other Unit Adjustments
Primary Limit
The primary limit is located on the heating compartment
vestibule panel. This limit is factory set and requires no
adjustment.
Flame Rollout Switches (Two)
These manually reset switches are located on the front of
the burner box. These limits are factory set and require no
adjustment.
Pressure Switch
The pressure switch is located in the heating compartment
on the cold end header box. This switch checks for proper
combustion air inducer operation before allowing ignition
trial. The switch is factory set and must not be adjusted.
Temperature Rise
After the furnace has been started and supply and return
air temperatures have been allowed to stabilize, check
the temperature rise. If necessary, adjust the blower
speed to maintain the temperature rise within the range
shown on the unit nameplate. See Table 21 for allowable
heating speeds. Increase the blower speed to decrease
the temperature. Decrease the blower speed to increase
the temperature rise. Failure to adjust the temperature rise
may cause erratic limit operation.
Fan Control
Ignition Control 103217-03
The fan on time of 45 seconds is not adjustable. The heat
fan off delay (amount of time that the blower operates after
the heat demand has been satisfied) may be adjusted by
changing the jumper position across the five pins on the
integrated control. The unit is shipped with a factory fan
off delay setting of 90 seconds. The fan off delay affects
comfort and is adjustable to satisfy individual applications.
Adjust the fan off delay to achieve a supply air temperature
between 90° and 110° F at the moment that the blower
is de-energized. Longer off delay settings provide lower
return air temperatures; shorter settings provide higher
return air temperatures. See Figure 56.
Ignition Control 107163-01
The heat fan-on time of 30 seconds is not adjustable The
heat fan-off delay (amount of time that the blower operates
after the heat demand has been satisfied) may be adjusted
by changing the two position dip switch on the integerated
control, to one of four slections. Blower off delay is factory
set at 90 seconds. For other blower off delay settings,
SW2-1
SW2-2
60
OFF
ON
90*
OFF
OFF
120
ON
OFF
180
ON
ON
* Factory setting
Table 20. Blower Delay Select
Figure 56.
Heat Fan Off Time in Seconds
To adjust fan-off timing, reposition jumper across pins to
achieve desired setting.
NO JUMPER
60 90
12
0
180
60 90
12
0
180
60 90
12
0
18
0
60 90
12
0
18
0
60 Second
off Time
90 Second
off Time
120 Second
off Time
180 Second
off Time
Constant Torque Motor
These units are equipped with a constant torque ECM
motor. It has a DC motor coupled to an electronic control
module,both contained in the same motor housing. The
motor is programmed to provide constant torque at each of
the five selectable speeds. The motor has five speed taps.
Each tap requires 24 volts to energize.
Thermostat Heat Anticipation
Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.
Exhaust and Air Intake Pipe
1.
Check exhaust and air intake connections for tightness
and to make sure there is no blockage.
2.
Is pressure switch closed? Obstructed exhaust pipe
will cause unit to shut off at pressure switch. Check
termination for blockages.
3. Obstructed pipe or termination may cause rollout
switches to open. Reset manual flame rollout switches
on burner box assembly if necessary.
Electrical
1. Check all wiring for loose connections.
2. Check for the correct voltage at the furnace (with
furnace operating). Correct voltage is 120 VAC ± 10%.
3. Check amp–draw on the blower motor with the blower
compartment access panel in place.
Motor Nameplate____________ Actual____________
