Troubleshooting Oil Burners


Individuals involved in the installing and repairing of oil burners should be aware of a number of different indicators of malfunctions in the equipment, their probable causes, and some suggested remedies.

The average individual is most aware of malfunctions that warn the senses through excessive noise, smoke, or odor. These are external warning signals that require immediate investigation. Their nature is such that tracing the probable cause of the malfunction is made easier.

Excessive noise (pulsation, thumping, rumbling, etc.) in the heating unit is generally caused by a problem with the oil burner nozzle. It can usually be corrected by any one of the following methods:

• Replace the nozzle with one having a wider spray angle.
• Replace the nozzle with one having the next size smaller opening.
• Install a delayed-opening solenoid on the nozzle line (this reduces pulsation).

Sometimes a noisy fire is caused by cold oil originating from outside storage tanks. This noise may be greatly reduced or eliminated by pumping the fuel oil under 120 to 125 psi through the next size smaller nozzle.

Excessive smoke has a number of possible causes, including the

• The air-handling parts of the oil burner may be too dirty to operate efficiently.
• The combustion chamber or burner tube may be damaged by burn-through or loose materials.
• The oil burner nozzle may be the wrong size.

The dirty air-handling parts (e.g., the fan blades, air intake, and air vanes in the combustion head) can be made to operate more efficiently by a thorough cleaning. If the excessive smoke is caused by the oil burner nozzle, this can be corrected by replacing the nozzle with one that is a size smaller or one having the next narrower spray angle. A damaged combustion chamber is a more difficult problem to correct than the other two. In any event, all leakage through the walls must be eliminated before the oil burner can be expected to operate efficiently.

Excessive odors can be caused by flue obstructions or poor chimney draft. If the draft over the fire is lower than 0.02 to 0.04, it is usually an indication that the problem lies with the flue or chimney draft. The cause is usually an obstruction in the flue or poor chimney draft. Other causes of excessive odor include the following:

• Delayed ignition
• Too much air through the burner

Delayed ignition is commonly traced to a problem with the electrodes. This condition can result from a variety of causes, including the following:

• Improper electrode setting
• Insulator cracks
• A coating of soot or oil on the electrode
• Incorrect pump pressure setting
• Incorrect spray pattern in the nozzle
• Clogged nozzle
• Air shutter open too far

Table 1-6 lists a number of recommended electrode settings that should eliminate delayed ignition if the electrode setting is the cause of the problem. The type of nozzle spray pattern can also result in delayed ignition. This is particularly true when using a hollow spray pattern in oil burners firing 2.00 gph and above. It can be corrected by replacing the nozzle with one having a solid spray pattern.

table 1 6 Troubleshooting Oil Burners

Table 1-7 lists a variety of problems encountered with oil burners, many of which are of an internal nature and require a great degree of experience and training to correct.

Table 1-7 Oil Burner Troubleshooting

Symptom and Possible Cause Possible Remedy
No heat—circulator (pump) off and burner running.
(a) Defective circulator. (a) Replace circulator.
(b) Defective thermostat. (b) Replace thermostat.
(c) Defective relay. (c) Replace relay.
(d) Defective aquastat. (d) Replace aquastat.
(e) Incorrect aquastat setting. (e) Reset aquastat.
(f) Loose or disconnected wiring. (f) Tighten or reconnect wiring.
(g) Defective zone valve. (g) Replace zone valve.
No heat—both circulator (pump) and burner running.
(a) Defective or loose circulator coupling. (a) Repair or replace.
(b) Broken circulator impeller. (b) Repair or replace circulator.
(c) Air trapped in lines. (c) Locate point of entry and repair; purge air from lines.
(d) Loose or disconnected wiring. (d) Tighten or reconnect wiring.
(e) Defective zone valve. (e) Replace zone valve.
(f) Frozen flow valve. (f) Repair or replace flow valve.
No oil flow at nozzle.
(a) Oil level below intake line in oil storage tank. (a) Fill tank with oil.
(b) Clogged strainer. (b) Remove and clean strainer.
(c) Clogged filter. (c) Replace filter element.
(d) Clogged nozzle. (d) Replace nozzle.
(e) Air leak in intake line. (e) Tighten all fittings in intake line; tighten unused intake port plug; check filter cover and gasket.
(f) Restricted intake line (high vacuum reading). (f) Replace any kinked tubing and check valves in intake line.
(g) Air-bound two-pipe system. (g) Check for and insert bypass plug. Make sure return line is
below oil level in tank.
(h) Air-bound single-pipe system. (h) Loosen gauge port plug or easyflow valve and bleed oil for
15 seconds after foam is gone in bleed hose. Check intake line fittings for tightness and tighten if necessary. Check all pump plugs for tightness and tighten if necessary.
(i) Slipping or broken coupling. (i) Tighten or replace coupling.
(j) Rotation of motor and fuel unit is not the same as indicated by arrow on pad at top of unit. (j) Install fuel unit with correct rotation.
(k) Frozen pump shaft. (k) Check for water and dirt in tank and correct as necessary;
return defective pump to manufacturer or service center for repair or to be replaced.
Noisy operation.
(a) Bad coupling alignment at fuel unit. (a) Loosen fuel unit mounting screws slightly and shift fuel unit in different positions until noise is eliminated. Retighten mounting screws.
(b) Air in inlet line. (b) Check all connections for damage. Replace as necessary. Use only good flare fittings.
(c) Tank hum on two-pipe system and inside tank. (c) Install return-line hum eliminator in return line.
Pulsating pressure.
(a) Partially clogged strainer. (a) Remove and clean strainer.
(b) Partially clogged filter. (b) Replace filter element.
(c) Air leak in intake line. (c) Tighten all fittings; replace damaged fittings and/or damaged intake line.
(d) Air leaking around strainer cover. (d) Check for loose cover screws and tighten securely. Check for damaged cover gasket and replace if necessary.
Low oil pressure.
(a) Defective gauge. (a) Replace defective gauge.
(b) Burner nozzle capacity is greater than fuel unit capacity. (b) Replace fuel pump with one of correct capacity.
Improper nozzle cutoff.
(a) Trapped air causing fuel pump operating problem. (a) Insert pressure gauge in nozzle port of fuel pump. Run burner. If burner shuts down after a minute of operation and
pressure drops from normal operating pressure and stabilizes, the fuel pump is running and the problem is with trapped air. Correct as necessary.
(b) Defective fuel pump. (b) Insert pressure gauge in nozzle port of fuel pump. Run burner. If burner shuts down after a minute of operation and
pressure drop is 0 psi, fuel pump is defective and should be replaced.
(c) Filter leaks. (c) Check face of cover and gasket for damage and repair or replace as necessary.
(d) Loose strainer cover. (d) Tighten strainer cover screws.
(e) Air pocket between cutoff valve and nozzle. (e) Run burner by stopping and starting unit until smoke and afterfire disappear.
(f) Partially clogged nozzle strainer. (f) Clean strainer or change nozzle.
(g) Leak in nozzle adapter. (g) Change nozzle and adapter.
Oil leak—oil leaking inside burner.
(a) Seal leaking. (a) Replace seal or pump.
(b) Blown seal in a single-pipe system. (b) Check to see if bypass plug has been left in fuel pump. Replace pump.
(c) Blown seal in a two-pipe system. (c) Check for kinked tubing or other obstructions in return line. Replace pump.
(d) Cracked nozzle adapter. (d) Replace nozzle adapter.
(e) Defective pump piston. (e) Replace pump.
(f) Loose fitting. (f) Tighten or replace fitting.
(g) Loose fuel unit cover. (g) Tighten cover screws.
(h) Loose plugs or fittings. (h) Dope with good-quality thread sealer; retighten plugs or fittings.
(i) Leak at pressure adjustment screw or nozzle plug caused by damaged washer or O-ring. (i) Replace washer or O-ring as necessary.
(j) Damaged gasket. (j) Replace gasket.
Oil leak—oil leaking on outside of burner.
(a) Loose fittings. (a) Tighten fittings.
(b) Defective fittings. (b) Replace fittings.
(c) Damaged gasket. (c) Replace gasket.
Burner running—no oil pumping into combustion chamber and no fire in chamber.
(a) No oil in storage tank. (a) Fill storage tank.
(b) Clogged fuel pump. (b) Repair or replace fuel pump.
(c) Defective fuel pump. (c) Replace fuel pump.
(d) Clogged nozzle. (d) Clean or replace nozzle.
(e) Damaged or defective nozzle. (e) Replace nozzle.
(f) Clogged filter. (f) Clean or replace.
(g) Obstructed oil line. (g) Remove obstruction or replace fuel line.
(h) Closed oil valve. (h) Repair or replace oil valve.
(i) Loose or defective oil pump coupling. (i) Tighten coupling or replace oil pump.
(j) Defective oil valve. (j) Replace valve.
(k) Lost prime. (k) Reestablish prime or replace pump.
Burner running—oil pumping into combustion chamber but no fire in chamber.
(a) Chamber obstructed. (a) Locate and remove obstruction.
(b) Too much air. (b) Adjust to proper level.
(c) Water contaminating the oil. (c) Locate point of contamination and repair; drain and replace oil.
(d) Defective or weak ignition transformer. (d) Replace ignition transformer.
(e) Dirty electrodes. (e) Clean electrodes.
(f) Cracked or broken electrodes. (f) Replace electrodes.
(g) Loose wires. (g) Tighten connection or replace wires.
(h) End cone obstruction. (h) Repair.
Smoky fire.
(a) Improper pump pressure. (a) Set proper pump pressure or replace defective pump.
(b) Incorrect nozzle. (b) Replace nozzle.
(c) Distorted and burnt end cone. (c) Replace.
(d)Water contaminating the oil. (d) Locate point of contamination and repair; drain and replace oil.
(e) Dirty boiler. (e) Clean boiler.
(f) Dirty fan. (f) Clean fan
(g) Defective combustion chamber. (g) Replace.
Burner fails to restart after resetting safety relay.
(a) Power off. (a) Restore electricity to burner.
(b) Defective burner motor. (b) Replace burner motor or burner.
(c) Defective fuel pump. (c) Replace fuel pump.
(d) Defective safety relay. (d) Replace safety relay.
(e) Defective on-off switch. (e) Replace switch.
(f) Tripped circuit breaker. (f) Reset circuit breaker; call electrician if problem continues.
(g) Blown fuse. (g) Replace fuse; call electrician if problem continues.
(h) Loose or disconnected wiring. (h) Reconnect wires and tighten wiring connections.
Flame pattern not centered.
(a) Improperly positioned burner. (a) Reposition burner.
(b) Contaminated fuel. (b) Locate source of contamination and repair; drain and replace fuel.
(c) Obstruction in combustion chamber. (c) Locate and remove obstruction.
Water leaking from boiler pressure relief valve with pressure under 30 psi.
(a) Defective pressure relief valve. (a) Replace pressure relief valve.
Water leaking from boiler pressure relief valve with pressure at 30 psi or greater.
(a) Defective feed valve. (a) Replace valve.
(b) Holes or cracks in coils. (b) Replace coils.
(c) Expansion tank full. (c) Correct as necessary.
(d)Water temperature above 210°F . (d) Reduce water temperature; replace valve.

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