Reznor SCE Unit Installation Manual - Manual (Page 28)

Form RZ-NA I-SCE, Page 28
21D. Computer
Controlled
Electronic
Modulation
(cont'd)
Is there 24 volts
between Terminal 2 on #1
Time Delay Relay and
Terminal 7?
Go to
Troubleshooting
Chart for heater.
Is there 24 volts
between Terminal 84 and
Terminal 7?
Is the
damper open?
Is there voltage
between Terminal 88 and
Terminal 7?
Is there voltage
between Terminal 4 on
ignition permissive relay and
Terminal 7?
Replace #1 time
delay relay.
Replace ignition
permissive
relay.
Check combustion
damper lower end switch
adjustment. If necessary,
replace end switch.
Is there voltage
between Terminal 87 and
Terminal 7?
Check combustion
damper lower end switch
adjustment. Replace end
switch if necessary.
Place a jumper
across Terminal
86 and Terminal 7.
Did the
damper close?
Replace motor
run time delay
relay.
Replace combustion
damper gear motor.
Replace primary
manifold
pressure switch.
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO NO
YES
YES NO
Measure manifold
pressure
during burner cycling.
When the
manifold pressure is
BELOW 1.0" w.c., is there a steady
voltage between Terminal 95
and Terminal 7?
Replace secondary
manifold pressure
switch.
While the
burner is cycling, is
there a steady voltage
between Terminal 84 and
Terminal 2?
Replace the
primary manifold
pressure switch.
When the
manifold pressure is
ABOVE 1.5" w.c., is there a steady
voltage between Terminal 95
and Terminal 7?
Replace secondary
manifold pressure
switch.
Is there voltage
between Terminal 4 of the
ignition premissive relay and
Terminal 7?
Replace ignition
permissive
relay.
YES
NO
YES
NO
YES
NO
Symptom - Part 1:
Main burners are inoperative.
Assumes that 24 volts is
available between Terminal 2
and Terminal 7.
General Instructions: For each step,
check to ensure that the wiring is not
defective and that the wiring connec-
tions are secure.
Symptom - Part 2:
Steady call for heat - burner cycles.
Assumes that 24 volts is available between Terminals 11 and 7 and Terminals 2 and 7.
tioner accepts a 4-20 milliamp signal. In the "off" positions, the conditioner accepts a 0-10V
signal. The conditioner converts the signal to the 0 to 20 volt DC current required to control the
modulating valve. The heater functions and is equipped in the same way as described in Para-
graph 21C (Option AG39) except that with computer control the temperatures are selected through
the software and there is no temperature selector or duct sensor.
FIGURE 28 - Troubleshooting Guide for Checking Bypass Combustion Air Damper Safety Circuit on
Model SCE with Option AG39 or AG40