Dunkirk Excelsior EXB Series Supplemental Instructions page 19

Riello 40BF blocked vent safety (BVS) Operation
External Action
Thermostat calls for heat.
Call for heat is satisfied.
Pressure switch contacts open and
cause burner to re-cycle.
RIELLO 40BF BURNER TROUBLESHOOTING
Problem
Reset control box.
1. Test for 120 Vac supply at sub-base be-
tween L (P) & N or terminals #3 and #5.
2. Turn off power supply- Remove control
box and jumper terminals #5 and #6.
Restore power.
3. Burner Starts
4. Burner Runs, post purge successful.
Aquastat Shows Error EE4.
OPERATION AND TROUBLESHOOTING
Appliance Response
• Burner enters pre-purge.
• After pre-purge, oil valve is energized and burner lights off.
• Burner operates in run mode.
• Normally closed pressure switch monitors for vent or combustion air intake blockage.
• Oil valve circuit is de-energized and valve shuts off.
• Burner motor runs for duration of burner motor-off delay.
• Burner motor turns off.
1. Check for vent blockage.
2. Check for combustion air intake blockage.
3. Ensure pressure tubes are connected properly and clear of obstructions.
4. Check burner set up.
Condition: Thermostat is calling for heat. Burner is not running.
Possible Cause
Burner starts.
Burner does not start
120 Vac present.
No voltage
Motor runs.
Motor does not run.
Burner stays in Pre-purge.
Burner continues to purge and
light off with immediate flame
dropout.
Burner locks out after trial for
ignition.
Some Aquastats limit post
purge time to 1 minute. Error
unique to early models of
L7248.
Remedy
Go to step #3
Go to step #1
Go to step #2
• Check system fuse, breaker or ensure service switch is ON.
• Verify all limits are closed.
• If using switching relay, verify 24 Vac at T-T.
• Verify BVS pressure switch is closed.
• Verify reduced voltage (42-52 Vac) between terminals #3 and #7.
• Ensure good contact between control box spades and sub-base terminals.
• Defective control box/ Replace.
• Verify electrical connections.
• Check for seized pump, motor, or fan against housing.
• Defective motor capacitor.
• Thermal overload (Hot motor).
• Faulty CAD cell or seeing light before trial for ignition.
• Coil wires on terminals #1 and #2 or #1 and #8 reversed.
• Open coil circuit; terminals #2 and #8.
• Open coil circuit; terminal #1
• Defective 42-52 Vac supply, terminals #3 and #7.
• Defective control box/ Replace
• Metal yoke for coil missing.
• Coil wire #2 and #8 reversed.
• Low resistance of coil holding circuit, terminals #1 and #2, (1350 ohms ± 10%).
• Verify BVS pressure switch is remaining closed upon light off.
• Low resistance or no contact on starting circuit of coil, terminals #2 and #8. (1.3-
ohm ± %)
• No oil supply- tank empty, valve closed, dirty filter, damaged supply lines.
• Defective or dirty oil valve stem, nozzle, or pump strainer.
• Broken pump drive key, defective pump or no oil pressure.
• Ignition electrodes shorted, cracked porcelain.
• Burner motor not up to speed.
• Excessive draft over fire.
• Defective control box/ Replace.
• Reset Post purge timer on Fan Timer Board to 45 seconds.
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P/N 240009355, Rev. C [11/15/2015]