508134-01
Issue 2045
Page 11 of 53
Primary Limit Control (Figure 6)
Primary limit (S10) used on
GDD92C
units is located
in the heating vestibule panel. When excess heat is
sensed in the heat exchanger, the limit will open. Once
the limit opens, the furnace control energizes the
supply air blower and de-energizes the gas valve.
The limit automatically resets when unit temperature
returns to normal. The switch is factory set and cannot be
adjusted. For limit replacement remove wires from limit
terminals, remove mounting screws, rotate limit switch
90 degrees and slowly remove from the vestibule
panel. Install replacement limit with same care. See
flash code 7 in Table 4 or Table 5 for troubleshooting if
limit switch opens during operation.
Install limit face down
Figure 6. Primary Limit Location and Heat Exchanger
The
GDD92
C
uses an internally redundant valve
to assure safety shut-off. If the gas valve must
be replaced, the same type valve must be used.
24VAC terminals and gas control switch are located on top
of the valve. All terminals on the gas valve are connected to
wires from the ignition control. 24V applied to the terminals
opens the valve.
Inlet and outlet pressure taps are located on the valve. A
manifold adjustment screw is also located on the valve. An
LP/Propane changeover kit is available.
Figure 7. Gas Valve
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD PRESSURE
ADJUSTMENT SCREW
(under barbed fitting)
To Measure Flame Signal - Integrated Control:
Use a digital readout meter capable of reading DC
microamps. See Figure 8 for flame signal check.
1.
Set the meter to the DC amps scale.
2.
Turn off supply voltage to control.
3.
Remove sensor wire from integrated control.
4.
Connect (-) lead to flame sensor wire.
5.
Connect (+) lead to Terminal FS on integrated control.
6.
Turn supply voltage on and close thermostat contacts
to cycle system.
7. When main burners are in operation for two minutes,
take reading.
