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HVACR215 – Mechanical for Oil

HVACR215 – Mechanical for Oil

Troubleshooting and Servicing the Oil Burner

Troubleshooting and Servicing the Oil Burner

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Servicing a Fuel Oil Burner

• Oil burner problems, symptoms, and possible causes are given in the following troubleshooting outline.

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Servicing a Fuel Oil Burner

I.Burner motor does not start, starts and locks out (CAD cell shuts off the control switch), or cycles.

A. Does not start.

1. Relay does not close (will not close or contacts dirty).

2. Safety lockout stays open.

3. Bad relay coil.

4. Low voltage.

5. Open high limit control.

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Servicing a Fuel Oil Burner continued

6. Broken wires or loose connections.

7. Relay transformer open.

8. Thermostat open (dirt on contacts, loose or dirty connections).

9. Stack switch open.

10. Heat sensing contacts out of place or open.

11. Motor overload open (burned out, or has dirty contacts).

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Servicing a Fuel Oil Burner continued

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B. Starts, but locks out.

1. No fuel oil out of nozzle.

•Clogged.

•Pressure too low.

•Pump not working.

•Loose motor coupling.

•Air leaks in fuel line.

•Fuel oil line handvalve closed.

• Strainers or screens clogged (filter, pump screen, or nozzle strainer).

• The pressure regulator in the pump body is stuck open.

• Vent on fuel oil tank closed.

• Empty fuel oil tank.

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Servicing a Fuel Oil Burner continued

2. Fuel oil coming out of nozzle but no ignition.

•Electrodes not positioned correctly.

•Insulators cracked.

•Ignition wires worn, loose, or with dirty connections.

•Transformer not operating.

•Primary wires worn, loose, or with dirty connections.

•Low line voltage.

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Servicing a Fuel Oil Burner continued

3. Fuel oil to nozzle, ignition OK, but no flame.

•Clogged nozzle.

•Clogged nozzle strainer.

•Nozzle loose.

•Pressure too low.

•Fuel oil too heavy (wrong oil or too cold).

•Excessive air or too much draft.

•Electrodes in wrong position.

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Servicing a Fuel Oil Burner continued

4. Flame burns only a few seconds.

•Flame sensor not in correct position.

•Stack switch not operating correctly.

•Excessive air or air too cold.

•Flame is too lean.

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Servicing a Fuel Oil Burner continued

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C. Cycles, but not on lockout.

1. Thermostat differential too close.

2. Anticipator set too close.

3. Limit switch set too low.

4. Overfired (reaches high limit temperature too quickly.)

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Servicing a Fuel Oil Burner

II. Burner does not operate correctly.

A. Smoke, soot, odors, and/or pulsating sound.

1. Wrong oil pressure.

2. Flame touches combustion chamber.

3. Not enough draft.

•Dirty chimney.

•Draft control is out of adjustment or it is stuck open.

•Dirty flue.

•Either the combustion chamber or the heat exchanger leaks.

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Servicing a Fuel Oil Burner continued

4. Poor mixing of air and oil.

•Nozzle is worn, loose, dirty, or drips.

•Oil pressure too low or high.

•Poor air velocity and turbulence.

•Not enough air (shutter closed too much, fan binding, or tight bearings).

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Servicing a Fuel Oil Burner continued

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B. Puffs back.

1. Water in oil.

2. Delayed ignition.

• Electrodes not positioned correctly or loose.

• Insulators carbonized.

• Nozzle worn, loose, dirty, or drips.

• Voltage drop when burner starts.

• Oil pressure too low or too high.

• Transformer leads loose or dirty.

• Transformer not operating correctly.

• Excessive air or high draft.

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Servicing a Fuel Oil Burner continued

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C. Noise.

1. Loose fan.

2. Loose shutter.

3. Worn pump.

4. Dirty strainer.

5. Air in oil line.

6. Transformer hum.

7. Draft control vibrates.

8. Motor coupling worn.

9. Motor and pump not lined up

correctly.

10. Relay contacts not seating tightly.

11. Oil suction line restricted.

12. Motor mounting loose.

13. Tight motor bearings.

14. Tank hum.

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Servicing a Fuel Oil Burner continued

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D. Fuel oil consumption is too high.

1. Nozzle is worn, loose.

2. Combustion chamber is dirty.

3. Too much combustion air (heat escapes up flue due to high flow of flue gases).

4. Poor mixing of air and oil.

5. Not enough draft over fire.

6. Air leaks into combustion chamber.

7. Oil pressure too high or too low.

8. Overfired, as noted by a high stack temperature.