52
HEATING
The 62X units may be equipped with gas or electric heat. The gas
heat may be staged or modulating control. The electric heat may
be staged or SCR (Silicon Controlled Rectifier) control.
Set Points
The control set points are the same for gas or electric heat.
Heating mode will be initiated based upon the outdoor air tem-
perature (OAT) heating set point (default is 55°F).
If the unit has modulating gas heat or SCR controlled electric heat,
the control will modulate to maintain a SAT (default is 70°F).
If the supply fan is set to enable only for cooling or heating, it will
continue to operate for two minutes after a heating mode.
Ignition Control
Units equipped with gas heat have an electronic ignition control.
The control is equipped with an LED for diagnostics and service.
See controller diagram Fig. 82.
Fig. 82 — Controller Diagram
Flame Current Sensor
The flame current sensor may be tested by the following
procedure:
SERVICE CHECKS
Flame current is the current which passes through the flame from
the sensor to ground. The minimum flame current necessary to
keep the system from lockout is 0.7 microamps. To measure flame
current, connect analog DC microammeter to the FC– and FC+
terminals per Fig. 83. Meter should read 0.7 µA or higher. If the
meter reads below “0” on scale, meter leads are reversed. Discon-
nect power and reconnect meter leads for proper polarity. See
Fig. 83.
See Table 23 for a detailed explanation of the LED codes.
Fig. 83 — Flame Current Detection
LED
FC- FC+
SERIES 35-61 IGNITION CONTROL MODULE
Fault Conditions and LED Key
NOTE: LED flashes on for 1/4 second, and off for 1/4 second
during default condition. Pause between fault codes is 3 seconds.
LED Steady On System Control Fault
1 Flash Combustion Air Flow Fault
2 Flash Flame with No Call for Heat
3 Flash Ignition Lockout
RED (+)
BLACK (-)
FC- FC+
MULTIPURPOSE
METER
SERIES 35-61 MODULE
USE
MICROAMP
SCALE
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