Other Unit Adjustments
NOTE − See troubleshooting flow charts if any safety switches are found to be open.
Primary Limit
The primary limit is located on the heating compartment vestibule panel. This limit is factory set and requires no ad- justment.
Flame Rollout Switches (Two)
These manually reset switches are located on the front of the burner box.
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. 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
The fan on time of 30 seconds is not adjustable. The 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 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−ener- gized. Longer off delay settings provide lower return air temperatures; shorter settings provide higher return air temperatures. See figure 55.
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.
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace operating).
3 − Check
Motor Nameplate__________Actual__________
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| HEAT |
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| NO JUMPER |
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| To adjust fan−off timing, reposition jumper across pins to |
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| achieve desired setting. |
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60 Second | 90 Second | 120 Second | 180 Second | ||||||||||||
off Time | off Time |
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60 | 90 | 120 | 180 | 60 | 90 | 120 | 180 | 60 | 90 | 120 | 180 | 60 | 90 | 120 | 180 |
FIGURE 55
Blower Speeds
Follow the steps below to change the blower speeds.
1 − Turn off electrical power to furnace.
2 − Remove blower access panel.
3 − Disconnect existing speed tap at integrated control speed terminal.
NOTE − Termination of any unused motor leads must be insulated.
4 − Place unused blower speed tap on integrated control PARK" terminal or insulate.
5 − Refer to blower speed selection chart on unit wiring dia- gram for desired heating or cooling speed. See Blower performance data beginning on the next page.
6 − Connect selected speed tap at integrated control speed terminal.
7 − Resecure blower access panel.
8 − Turn on electrical power to furnace.
9 − Recheck temperature rise.
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 ter- mination for blockages.
3 − Obstructed pipe or termination may cause rollout switches to open. Reset manual flame rollout switches on burner box assembly if necessary.
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