506305-01
Page 28 of 36
Issue 0938
is operating correctly.
Integrated Ignition/Blower Control Board
The integrated ignition/blower control board operates all
functions of the furnace and any accessories connected to it.
These models feature user-selectable blower “off” delay times
(60, 90, 120, and 180 seconds) that are factory set to provide
a 120-second blower “off” delay on heating (see connection
diagram on page 33).
Refer to the furnace wiring diagram while using the following
procedure to change motor speed:
1.
Turn off electrical power to the unit.
2.
Connect the desired speed tap for cooling on the
control board.
3.
For heating speed, check the temperature rise and, if
necessary, adjust blower speed tap to maintain
temperature rise within the range shown on the furnace
rating plate.
To use the same speed tap for both heating and cooling,
install a piggyback terminal on the speed tap using a
short jumper. Wire 1/4" quick connect terminals on both
ends to jumper the “HEAT” and “COOL” speed on the
control board.
4.
The remaining speed taps must be connected to dummy
terminals marked “PARK” on the control board.
Checking and Adjusting Gas Input
The minimum permissible gas supply pressure for the purpose
of input adjustment is 5" W.C. for natural gas and 11" W.C. for
propane gas. This furnace requires conversion for use with
propane (see
Accessories
section on page 29 for correct
kit). The maximum inlet gas supply pressure is 10.5" W.C. for
x
3600
x
=
Cubic Feet Per Revolution
BTU/HR
INPUT
# Seconds Per Revolution
Heating
Value
The heating value of the gas can be obtained from the local
utility company.
For Propane Gas:
The only check for the furnace rate is to
properly adjust the manifold pressure using a manometer and
Table 4 on page 29. Typical manifold set point for installations
at altitudes from 0 to 4500 feet above sea level is 10.0" W.C.
Temperature Rise
Check the temperature rise and, if necessary, adjust blower
speed to maintain temperature rise within the range shown on
the unit rating plate.
For Natural Gas:
Check the furnace rate by observing the
gas meter, when available, making sure all other gas
appliances are turned off. The test hand on the meter should
be timed for at least one revolution. Note the number of
seconds for one revolution.
natural gas and 13" W.C. for propane.
Gas input must never exceed the value shown on the furnace
rating plate. The furnace is equipped for rated input at
manifold pressures of 3.5" W.C. for natural gas or 10.0" W.C.
for propane gas.
To measure inlet or outlet pressure, remove plug from
desired pressure tap (inlet or outlet) as shown in Figure 38
and connect a water manometer or gauge to the proper
pressure tap.
To adjust the regulator, disconnect the hose and remove
the barbed fitting from the gas valve. Turn the adjusting screw
on the regulator clockwise to increase pressure and input;
counterclockwise to decrease pressure and input.
Replace the barbed fitting and reconnect the hose after adjusting
the regulator. Be sure to replace the inlet and outlet pressure
tap plugs after testing and/or adjusting gas input.
The furnace rate must be /- 2% of the appliance
rating input.
CAUTION
Figure 38
Checking and Adjusting Gas Input
Inlet
Pressure Tap
1/8” NPT
Alternate Lever
Switch
