34
of full flow, but is also
not field adjustable. At the end of the dwell
time, the main valve opens, allowing full gas flow.
Testing Operating Pressure:
a.
Remove furnace door and set the gas valve in the OFF
position.
b.
Using a 3/16” Allen wrench, remove the plug from the right
side of the valve.
c.
Install the barbed adapter in the plug hole. Tighten by
hand at first, then with an open end wrench. Do not
overtighten!
d.
Install the hose and manometer to the barbed fitting. Be
sure to check all connections for leaks.
e.
Set the gas valve switch to the ON position.
f.
With the valve in the ON position, set the thermostat
above room temperature so the furnace will run throughout
the test procedure.
g.
With the furnace operating, check for valve staging. The
operating pressure should be 3.5” WC for Natural Gas,
10” WC for LP gas.
Blower Assembly – If the blower motor has power to it
(heating speed and neutral) and motor does not start, motor
has electrically opened up. NOTE: Some models incorporate
a capacitor, this should be checked first.
To replace motor:
1.
Remove wires going to motor.
2.
Remove single Phillips screw in upper left corner.
3.
Raise entire blower assembly slightly and swing out to left.
4.
Loosen set screw on blower hub.
5.
Remove screws holding motor to blower housing.
6.
Remove motor and replace. NOTE: Some motors are
torsion-flex mount and some are band around mount. See
picture below.
7.
Reverse steps 1-5 to reinstall. Note: Be sure to tighten
blower set screw on flat of motor shaft.
Heat Exchanger Replacement – The heat exchanger is the
largest and most expensive item in the furnace. Before
replacing the heat exchanger, make certain it is the problem.
Call the technical service department if you have any uncer-
tainty about a heat exchanger failure. Heat exchangers can
become sooted up due to debris in top of furnaces,
improper conversion, or not being converted to LP. See
troubleshooting section on flue and conversion section
of this manual. This condition is not covered under
warranty. See page 22 of this manual – To Test Heat
Exchanger.
Note: The furnace does not have to removed to replace the
heat exchanger.
Change Out Procedure:
1.
Disconnect all gas and electrical power to furnace.
2.
Disconnect flue.
3.
Remove burner assembly.
4.
Remove combustion air pipe and combustion blower.
5.
Remove blower assembly.
6.
Remove blower deck panel. NOTE: Panel will be difficult
to remove with furnace in alcove.
7.
Remove front panel. NOTE: One of the panel screws is
located through the combustion air box on the right.
8.
Lift up divider panel out of side cabinet lances.
9.
Support the underside of the heat exchanger with a
board.
10. Remove top collector panel. NOTE: Two screws attach
through top of cabinet.
11. Remove the other eight screws in the top of the cabinet
that hold the combustion air box.
12. Remove heat exchanger and replace.
13. Reverse steps one through eleven to reinstall.
NOTE: Be sure to install all new gaskets (from gasket
replacement kit).
14. Start up and check out for proper operation.
Picture 23. Blower Assemblies
Band Around Mount
Torsion Mount
Figure 25. Heat Exchanger
