Dunkirk Excelsior EXB Series Supplemental Instructions page 17

Beckett NX: System and General Troubleshooting
Problem
Boiler will not start.
Boiler will not start without
first pushing oil primary
control reset button.
(Happens on frequent basis)
Boiler starts, but cuts out
requiring manually resetting
the oil protector reset button
OPERATION AND TROUBLESHOOTING
Possible Cause
Thermostat not calling for heat.
No power to Boiler.
Thermostat faulty.
Oil primary control faulty.
Photo Cell wiring shorted or
room light leaking into photo cell
compartment
Open safety switch.
Photo Cell (Cad Cell) defective.
No fuel oil.
Clogged nozzle.
Clogged oil filter.
Blocked Vent Safety Circuit opening.
Low oil pump pressure.
Air getting into fuel oil lines, or fuel
oil line dirty, clogged, or in some
manner defective.
Defective burner motor.
No fuel oil.
Clogged nozzle.
Clogged oil filter.
Blocked Vent Safety Circuit opening.
Low oil pump pressure.
Air getting into fuel oil lines, or fuel
oil line dirty, clogged, or in some
manner defective.
Defective burner motor.
Water or contaminants in oil.
Remedy
• Check thermostat and adjust. Also, check thermostat for accuracy; if it is a mercury
switch type, it might be off level.
• Check Boiler switch, main electrical panel Boiler fuse or circuit breaker. Also look for any
other hand operated switch, such as an old poorly located Boiler switch, which was
not removed during Boiler replacement.
• Remove thermostat wires from control terminals T-T. Place a jumper across T-T. If Boiler
starts, replace thermostat, thermostat sub-base (if equipped), or both.
• Check reset button on oil primary control.
• Check photocell (cad cell) wiring for short circuits. Also, check for room light leaking
into cad cell compartment. Repair light leak if necessary. See Table C-3.
• Check for open limit or auxiliary limit. Also, check internal wiring connections; loose
connectors, etc.
• If call cell is dirty, clean it. (Determine why cad cell is getting dirty). If cad cell is poorly
aimed, realign it. NOTE: The photocell should have a resistance of 100KΩ in absence
of light; a maximum of 1500Ω in the presence of light. Ensure that room light is not
leaking into the cad cell compartment. (See diagnostic light section).
• Check fuel oil supply. Check that all hand operated fuel oil valves are in the open posi-
tion. Fill oil storage tank if necessary.
• Replace nozzle with high quality replacement. Use rating plate or Tables in Appendix A
as a guide.
• Replace oil tank filter or in-line filter if used.
• Pressure switch open:
• Check pressure tubes for proper connection or possible obstructions.
• Check venting for blockage.
• Check combustion air intake for blockage.
• Check pressure switch operation.
• Connect pressure gauge to oil pump. Adjust pump pressure, or replace oil pump if nec-
essary. Ensure that erratic pressure readings are not caused by defective fuel oil line.
• Check fuel oil lines. Replace any compression fittings found with high quality flared
fittings. Check for any signs of oil leaks. Any oil leak is a potential source of air or
contaminants.
• Check burner motor. If burner motor is cutting out on over-load, determine why.
Replace if necessary.
• Check fuel oil supply. Check that all hand operated fuel oil valves are in the open posi-
tion. Fill oil storage tank if necessary.
• Replace nozzle with high quality replacement. Use rating plate or Tables in Appendix A
as a guide.
• Replace oil tank filter or in-line filter if used.
• Check pressure switch on BVS to ensure closed.
• Pressure switch open.
• Check pressure tubes for proper connection or possible obstructions.
• Check venting for blockage.
• Check combustion air intake for blockage.
• Check pressure switch operation.
• Connect pressure gauge to oil pump. Adjust pump pressure, or replace oil pump if nec-
essary. Ensure that erratic pressure readings are not caused by defective fuel oil line.
• Check fuel oil lines. Replace any compression fittings found with high quality flared
fittings. Check for any signs of oil leaks. Any oil leak is a potential source of air or
contaminants.
• Check burner motor. If burner motor is cutting out on over-load, determine why.
Replace if necessary.
• Drain fuel oil storage tank, replace fuel oil. (Consult with fuel oil supplier).
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P/N 240009355, Rev. C [11/15/2015]