Heating Oil Safety

Here are the most common problems that can occur with an oil heating system.


If you smell oil, it generally means your system requires maintenance. The fumes can be dangerous and may signal a crack or misalignment in your oil burner. When an oil burner ignites, it pressurizes the combustion chamber for a few seconds. The smoke from the unburned oil can move into the surrounding fresh air chamber–the heat exchanger—that then circulates into the house. If there is a crack or a hole in the heat exchanger, you will smell oil fumes or a sooty wall around a heating vent is another sign of internal problems with your system that need repair.

Fumes you cannot smell like carbon monoxide are even more dangerous. Carbon monoxide (CO) is a by-product of combustion, present whenever fuel is burned and you cannot smell the fumes. Besides furnaces, any gas-fueled appliance produces it—clothes dryers, ovens, grills, fireplaces, etc. If your home is properly vented, CO will be safely directed outside. However, with a cracked heat exchanger, vents can become blocked and inadequate air supply for combustion appliances can force contaminated air back into the home. You will smell an oil odor (and possibly see smoke and soot), which should prompt you to call a technician, before any carbon monoxide is released. Ironically, the risks of carbon monoxide have increased in the past several years because sealing up and weatherizing our homes reduces ventilation.

Even though the dangers of carbon monoxide are much lower in a house with an oil heat system (as opposed to a gas furnace), a CO detector (available at your local hardware store for about $20) is always a good idea.


The chance of a fire from heating oil is extremely remote. Heating oil will not explode. In fact, if you drop a match into heating oil it will go out, as if it were dropped into water. Your oil has to be heated to 140 degrees and vaporized before it will catch fire.


Oil heat means oil tanks, which require diligent maintenance. The biggest possible problem with an oil tank, whether your tank is indoors or outdoors, above or below ground, is the possibility of a leak. An oil leak is a serious problem; it can contaminate your drinking water, your soil, and cause health problems. It can also be very costly to repair.

How do you know if you have a leak? Here are the most common signs:

  • A sharp, unexplained spike in consumption. If you’re not sure, your heating oil distributor should be able to track your fuel use, making sure it’s consistent with the weather.
  • A change in the performance of your furnace, or if your furnace is suddenly shutting off frequently.
  • Changes or loss of the vegetation around your tank (for outdoor tanks).
  • Oil odors in areas other than around the oil burner.
  • A different taste or odor to your water.
  • Oil or an oily sheen in your basement’s low point or drains, nearby culverts, ditches, storm drains, streams, or ponds.

Other ways to check for a leak:

Some above ground oil tanks have a small oil-water separator (it looks like a small bowl at the bottom of the tank). A small amount of water in the separator is normal – usually condensation from the tank. But if there is a suddenly a lot of water, there might be a leak.

If you have an above ground oil tank, check for signs of corrosion (rust), particularly at the bottom of the tank. Residential oil tanks usually rust from the inside out; so if signs of aging are visible, it’s probably time to replace the tank. Tanks that are 15 years old and older have a dramatically higher rate of rusting.

You should check your tank vent as well to make sure it’s not clogged with ice, snow, or insect nests. A clogged vent may result in overfilling during refueling, which can cause a spill. The pipes, hoses, valves, and fittings connected to a tank can also be sources of leaks, especially in an older system