Why Does My Furnace Smell Like Diesel?

Does your furnace smell like diesel gasoline?

If your furnace smells like diesel, then it might be a cause for concern. This depends, however, on the type of furnace you are using in your home or business. The majority of United States residents use gas or electric furnaces to heat their homes. If one of these furnaces lets off an odor, it will typically be either rotten eggs, gas, hot electrical, or smoke. However, there is a small percentage of homes in the United States that use oil furnaces. These provide efficient heat with a clean-burning fuel. Occasionally we have customers saying that their oil furnace smells like diesel or burning oil. We’re here to discuss a few reasons why that might be, and what to do if your furnace smells like diesel.

Understanding Why Your Oil Furnace Smells Like Diesel

It’s important to pay attention to the odors coming from your oil furnace (or any furnace, for that matter). If your furnace smells like diesel or oil, then quickly inspect the unit visually and see if any smoke or flames emanating from it. If so, shut it off immediately and contact your local furnace repair company. For when you don’t see any obvious signs of a malfunction, we’ve compiled the following list of oil furnace problems that might lead to an oil furnace that smells like diesel.

Potential problems and how to fix them:

  1. Plugged Nozzle – a plugged nozzle can be cleaned by hand in order to maintain the longevity of your furnace and eliminate smells. If the nozzle is too far gone, you will likely need to purchase a brand new one.
  2. Clogged chimney – this can cause hot smoke to come out of your oil furnace, which could be the source of the diesel smell. Clean out the chimney to eliminate the odor.
  3. Faulty burner – sometimes a simple adjustment of the burner is all it takes to eliminate diesel or smoke smells. A burner that gets too much air will burn too big and too cold, and will actually not burn all the oil passing through the flame. This could result in excess oil and smoke, as well as inefficient heat.
  4. Improper end cone – an end cone that is the wrong size or that has rusted and burned away can be the cause for odors or smoke. Have a professional technician replace the end cone for you.
  5. Cracked heat exchanger – this can be a result of not using the right sized nozzle, or else from a burner assembly that has not been adjusted properly. A cracked heat exchanger is no joke, and it will generally require you to purchase a new furnace entirely.
  6. Delayed ignition – if the droplets of oil passing through your oil furnace do not ignite, they simply create a dense fog. Once they do ignite (in a delayed ignition) all of the previously unburned oil will light at once and create a large, hazardous flame. This also results in excessive smoke. If your furnace smells like diesel or oil and it is unlit, do NOT light it. Call a service technician to clean up the excess oil and light it for you.
  7. Dirty heat exchanger – an oil furnace that is smoking heavily (usually from a burner that is not getting enough air) will produce a lot of smoke. This will quickly gunk up the heat exchanger, which will then need to be cleaned in order to eliminate odors.
  8. Furnace is crowded – if you have objects that are crowding the oil furnace itself, then they could be heating up and causing smoke. This is an extreme fire hazard, and you should always leave adequate space around the furnace for air ventilation.
  9. Spillover from a recently filled oil tank – if you recently had your oil tank filled, then it is common for your furnace to smell like diesel or oil for a few days. The smell should dissipate over time, unless there is an oil leak. If the smell persists, call your furnace repair provider immediately.

A Carbon Monoxide Detector Can Save Your Life

We also want to take a moment to remind you to always have a carbon monoxide detector near your furnace, whether it’s electric, gas, or oil powered. Carbon monoxide is colorless, odorless, tasteless, and deadly. Known as the silent killer, CO2 has the ability to kill you in your sleep as it replaces the oxygen in your home. Purchase a battery powered carbon monoxide detector from your local hardware store and ensure that it is fully operational at all times, and that your furnace is properly maintained and vented.

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