How to Adjust a Fuel Oil Furnace

Fuel oil furnace annual inspection and adjustment will save money in the long run.

Although fuel oil furnaces are sturdy appliances, they still need periodic cleaning and adjustment to keep them operating at peak efficiency. For example, a faulty combustion fan will starve the burner of air. Insufficient air leads to an oil-rich mixture and incomplete combustion. This lowers heat output, increases soot build-up and drives up your fuel oil consumption. DIY troubleshooting and regular annual inspection will save you money in the long run by keeping your heating bills to a minimum and preventing costly breakdowns.

Things You'll Need

• Burner nozzle
• Wrench
• Glass jar
• Bucket
• Oil filter
• Screwdriver
• Heat resistant foil tape
• Wire brush
• Rag
• Solvent
• Shop vac
• Socket wrench
• Return air filter

Instructions

1. Press the reset button if the furnace fails to start. This is located either on the flue pipe or on the top of the burner motor. If the furnace ignites but fails to stay on, look for a blown fuse or tripped breaker switch. If this proves to be the case, there may be an electrical short or malfunction. Ask your heating contractor to diagnose and repair the fault.

2. Replace the burner nozzle if the motor is running but there is no ignition; consult your owner's manual for instructions before doing so.

3. Turn off the fuel oil shut-off valve. Use a wrench to undo the pipe leading to the fuel pump feeding the burner assembly. Open the shut-off valve and drain off a glass jar of fuel oil. Hold the jar up to the light and check for water bubbles in the bottom. If the fuel is contaminated, drain off a gallon or two into a bucket and retest. If water is still present, have the fuel oil delivery company drain and clean out the tank.

4. Carry out your annual inspection by first shutting off the oil feed valve and turning off the power to the furnace by tripping the relevant breaker switch. This is located either on the burner sub-panel or on the main house electrical panel. Allow enough time for the appliance to cool down.

5. Replace the oil filter. Consult the owner's manual for the correct procedure and to identify the replacement part number.

6. Inspect the burner assembly for leaks. If you notice smudges or pooled fuel oil on the burner mounting plate, have your heating contractor carry out the necessary repairs.

7. Go over the furnace electrical system carefully. Look for bare wires and loose connections. Tighten terminal screws with a screwdriver where necessary. Call an electrician to replace bare or damaged wires. If the furnace stopped working suddenly, look for blown fuses, tripped reset buttons or tripped breaker switches. If this does not correct the problem, consult your heating contractor.

8. Inspect the exhaust stack. Look for leaky joints, corrosion or holes in the pipe. Replace damaged or corroded sections where necessary. Seal leaky joints with heat resistant foil tape.

9. Clean the draft regulator near the top of the exhaust stack as directed in the owner's manual. Brush off oily soot deposits with a wire brush and a rag moistened with solvent. Pay special attention to the underside of the hinged butterfly plate. Lubricate exposed hinges where possible. Do not interfere with the draft regulator settings; this mechanism should be adjusted only by a qualified technician.

10. Brush off gray combustion deposits or soot from the combustion chamber with a wire brush, if it is accessible. Clean out loose debris in the bottom of the combustion chamber with a shop vac.

11. Remove the side cover plate from the return air blower with a screwdriver or socket wrench. Vacuum or wipe the blower blades clean with a rag. Clean the inside of the blower housing. Consult your owner's manual for the proper procedure to lubricate and clean the blower fan shaft and blower motor. Note: Some modern units are equipped with sealed bearings that don't require lubrication.

12. Inspect the blower fan belt; replace it if there are signs of wear. Consult your owner's manual for the correct belt tensioning procedure. Adjust it if necessary. Note: Many new furnaces' return air fans are coupled directly to the motor and do not have a fan belt.

13. Replace or clean the return air filter regularly according to the owner's manual.

14. Inspect the storage tank for evidence of leaks. If you can smell fuel oil, look for oil stains or puddles. Have a heating contractor replace the tank if necessary.

15. Restore electrical power to the furnace and turn the fuel oil supply valve on. Start the furnace and allow it to warm up. Inspect the exhaust outlet. If the smoke is black, consult your heating contractor. The burner either needs to be adjusted or the burner combustion air fan may be faulty. Note: black smoke on start-up is normal; this will go away after the furnace reaches operating temperature.

Tips & Warnings

• For safety's sake, burner adjustment should only be carried out by a qualified furnace technician.

References

• Michigan State University: Maintaining Conventional Residential Oil-Fired Heating Systems
• Mother Earth News: Oil-Furnace Troubleshooting