Puff backs

Think running out of oil is bad? How about having burned, smelly oil soot spread throughout your home? A puffback is an explosion of un-burned oil on the bottom of the combustion chamber in an oil-fired furnace, boiler, or water heater. In its worst form, puffbacks can be dangerous and can lead to oil residue contamination and fire. The problem is most often caused by a poorly-operating heating system that needs professional attention.
The strength of a puffback explosion can vary. It will depend on the amount of oil that is ignited, the heater appliance type, the condition of the equipment and so on. The puffback ignition can damage your heating appliance. If it is strong enough, it can cause your stackpipe to become disconnected, increasing the risk of carbon monoxide poisoning. Puffbacks also blow soot throughout you home.
The soot release from continual puffbacks can the release can be gradual or abrupt. A light explosion may just leave black dust around the heating unit. Stronger explosions can spread soot throughout your house. Forced hot air heat can easily spread soot from a puffback.
Before a catastrophic and potentially explosive puffback occurs, you'll generally have some warning in the form of gas odors and soot. Some signs of problems include:
Black soot and debris on top of your boiler, furnace, or water heater.
Soot stains on the ceiling or wall surfaces around the unit area.
Soft rumbling sounds from your burner after the furnace run cycle ends. Noises when your oil burner begins each run cycle. It may sound like a puff or bang. This is probably the unburned oil igniting.
Oil leaks or air leaks in the oil piping system or at the burner.
These are signs that your oil burning furnace or boiler is not burning properly. If you experience any of these warning signs, your system should be inspected and repaired.
One of the best ways to prevent puff backs and oil soot contamination is to have all of your oil fired heating appliances serviced regularly, normally once a year. During the rest of the year, be alert for odd smells and oil leaks. If you notice anything out of the ordinary, immediately call your heating service company.