035-14527-000 REV A (599)
Form 650.77-N3U
Unitary Products Group
19
9.
Turn the electrical and gas supplies back on, and, with
the burners in operation, check for gas leakage around
the plug with a soap and water solution.
ADJUSTMENT OF TEMPERATURE RISE
The temperature rise, or temperature difference between the
return air and the heated air from the furnace, must be within
the range shown on the furnace rating plate and within the
application limitations shown in Tables 3 or 4. After the tem-
perature rise has been determined, the cfm can be calcu-
lated.
After about 20 minutes of operation, determine the furnace
temperature rise. Take readings of both the return air and the
heated air in the ducts, about six feet from the furnace where
they will not be affected by radiant heat.
Increase the blower speed to decrease the temperature rise;
decrease the blower speed to increase the rise.
All direct-drive blowers have multi-speed motors. The blower
motor speed taps are located on the control module in the
blower compartment. To change the blower speed, refer to
the unit wiring label and Figure 16 on page19.
You may select a heating speed and a cooling speed. They
may be the same speed or a different speed.
To use the same speed tap for heating and cooling, the heat
terminal and cool terminal must be connected using a jumper
wire and connected to the desired motor lead. Place all
unused motor leads on Park terminals. Two are provided.
ADJUSTMENT OF FAN-OFF CONTROL SETTINGS
This furnace is equipped with a time-on/time-off heating fan
control. The fan on is field adjustable at 30 or 60 seconds.
The fan on is factory set at 30 seconds. The fan off is field
adjustable from 60 to 180 seconds. The fan off is factory set
to 60 seconds.
The fan-off setting must be long enough to adequately cool
the furnace, but not so long that cold air is blown into the
heated space.
The fan-off timing may be adjusted by setting the option
switches located (Refer to Figure 16 on page19) on the con-
trol board as follows:
Be sure that the gas valve pressure regulator cap
is replaced.
Do not energize more than one motor speed at a
time or damage will result.
FIGURE 16 : TYPICAL HEAT/COOL SPEED TAP
CONNECTIONS
WHITE-RODGERS CONTROL
To Set Fan-On By:
Set Switch 1
On - 30
Off - 60
To Delay Fan-Off By:
Set Switch
2
3
60 Sec.
On
On
90 Sec.
On
Off
120 Sec.
Off
On
180 Sec.
Off
Off
