Oil Burner Smoking or Soot? What to Do
From the Alcus family · Alcus Fuel Oil & Sons, Amityville · Updated November 1, 2026
Smoke coming from the boiler or furnace, black soot around the burner, or a loud "whump" when the heat came on? Here's what to do right now.
Do this right now
- Turn the burner off at the emergency switch. It's usually a red switch plate at the top of the basement stairs or near the boiler.
- Press the reset button once, at most. If the burner has locked out, one press is the limit. Repeated resets pump oil into the chamber, which can flood it and cause a puffback.
- Ventilate. Open windows and doors to clear smoke and fumes.
- Heavy smoke or fire? Get everyone out and call 911. If your carbon monoxide detector goes off, leave the house and call 911.
- Call us at 631-264-8800. Our no-heat line is answered 24/7. More steps on our emergency page.
What causes smoke and soot
- A worn or clogged nozzle. The nozzle sprays oil as a fine mist. When it wears or clogs, the oil doesn't burn cleanly.
- A dirty oil filter. Sludge from the tank can block the filter and starve the burner.
- The wrong air setting. Too little air makes smoke and soot.
- A cracked combustion chamber. The lining inside the boiler or furnace can crack over time and needs repair.
- A blocked chimney or flue. If exhaust can't get out, smoke and fumes can come back into the house.
What a puffback is
A puffback happens when oil vapor builds up in the chamber and then lights all at once. You may hear a bang or a whump. A puffback can push soot out of the boiler or furnace, through the vents and onto walls and furniture. Keep the burner off, don't try to restart it yourself, and call us. Call your insurance company about soot cleanup.
Prevent it with a yearly tune-up
Most smoking and soot problems are prevented by a yearly tune-up. We change the nozzle and filter, clean the unit and set the burner so it burns clean. See oil burner service, when to schedule a tune-up, and our service contract, which also puts you first in line when it's busy.
Keep a carbon monoxide detector near the boiler or furnace and on every sleeping floor, and test it.
Burner stopped but no smoke? Use the no-heat checklist.
Today's COD cash price · Amityville 11701 · 150–199 gal
$5.159/gal cash
Card price $5.359/gal · price for October 30, 2026, before sales tax. Prices vary by ZIP and order size.
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Questions
Why is my oil burner smoking?
Usually the burner isn't burning the oil cleanly. Common causes are a worn or clogged nozzle, a dirty filter, the wrong air setting, or a cracked combustion chamber. A technician needs to find the cause.
What is a puffback?
A puffback is a small explosion inside the boiler or furnace when built-up oil vapor lights all at once. It can blow soot through the house, out of vents and registers. Turn the burner off and call us.
Can I keep running a burner that smokes?
No. Turn it off at the emergency switch and call 631-264-8800. Running a smoking burner can spread soot and can be a carbon monoxide risk.
How do I prevent soot problems?
A yearly tune-up and cleaning prevents most of them: the technician changes the nozzle and filter, cleans the unit and sets the burner. A carbon monoxide detector near the boiler or furnace is a must.