Use and Care Manual

24
• On: cad cell is sensing ame.
• Off: cad cell is not sensing ame.
vii. Cad Cell Resistance Check: For proper
operation it is important that the cad
cell resistance is below 1600 ohms. During
a normal call for heat, the cad cell leads
can be unplugged from the control and the
resistance measured with a meter in the
conventional way.
Conduct these tests with ame present, see
chart below.
Flame Detection Range
Normal (0 - 1600 ohms)
Limited (1600 ohms to lockout)
3. CHECK OIL PRIMARY CONTROL
CAUTION
Due to the potential hazard of line voltage, only a
trained, experienced service technician should
perform the following safety checks.
This control contains no eld-serviceable parts.
DO NOT attempt to take it apart. Replace entire
control if operation is not as described.
a. Preliminary Steps
• Check wiring connections and power supply.
• Make sure power is on to the controls.
• Make sure limit control is closed.
• Check contacts between ignitor and the
electrodes.
• Check the oil pump pressure.
• Check the piping to the oil tank.
• Check the oil nozzle, oil supply and oil lter.
b. Check Safety Features
Safe Start:
• Place a jumper across cad cell terminals.
• Follow procedure to turn on burner. Burner
must not start, indicator light turns on and
control remains in Idle Mode.
• Remove jumper.
c. Simulate Ignition or Flame Failure:
• Follow procedure to turn on burner.
• Check cad cell resistance. If resistance is
below 1600 OHMS and burner runs beyond
safety cut-out time, cad cell is good.
• If safety switch shuts down burner and
resistance is above 1600 OHMS, open line
switch to boiler. Access cad cell under ignitor,
clean face of cad cell and see that cell is
securely in socket. Check gasket around
• At the end of four (4) minutes, the yellow light
will turn off and the control will automatically
return to standby mode.
c. Limited Recycle: This feature limits the number
of recycle trials (for each call for heat) to a
maximum of three trials. If the ame is lost
three times and does not successfully satisfy a
call for heat, the 7505 locks out.
d. Limited Reset (Restricted Mode): In order to
limit the accumulation of unburned oil in the
combustion area, the control can only be reset
three times. The reset count returns to zero each
time a call for heat is successfully completed.
e. T-T Jumper: Select models have pre-installed
T-T jumper. DO NOT remove jumper.
Note: DO NOT remove "T-T" jumper unless
wiring diagram indicates a direct connection
from thermostat and/or tankless heater aquastat
control to the oil burner primary control's "T-T"
terminal. Refer to appropriate wiring diagram,
see Figure 11a or 11b.
f. Diagnostic LED: The indicator light on oil
primary control provides lockout, recycle and
cad cell indications as follows:
• Flashing at 1 Hz (½ second on, ½ second off):
system is locked out or in Restricted Mode.
• Flashing at ¼ Hz (2 seconds on, 2 seconds
off): control is in Recycle Mode.
Figure 17: GeniSys 7505 Oil Primary Terminals,
LED's and Reset Button