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  • Writer's pictureRebecca Weaver

Fuel Oil Furnaces: A Beginner's Guide to Maintenance

A fuel oil furnace has a fuel tank that needs filled regularly, and will require more maintenance than the average furnace.
Fuel Oil Furnace

Fuel oil furnaces are known for being dependable and hearty. Their popularity has been on the decline for the last several decades, mostly because there are other options on the market more budget and eco-friendly. Because of this, it can be difficult to find information on them and even more difficult to find technicians who work on them in certain areas. The east coast and rural areas might be the two most common places to find fuel oil equipment, giving people who live there a better chance of finding some answers about these odd machines.

If you're a new homeowner and you now depend on a fuel oil furnace for heat, there are a few things you should know about them:

1. Fuel Oil Furnaces Require Annual Maintenance

Yes, that's right- REQUIRE. Out of all the HVAC equipment that exists, these ones rank in the top of the list when it comes to the importance of maintenance. Fuel oil works by burning oil, so when the unit is not cleaned regularly, it can start to soot up. This soot can cause parts to go bad, wear down the equipment, and gum up the unit. If you want your furnace to last as long as it's supposed to, it's important to get regular cleanings.

When well maintained, they last a very long time (typically 25 to 30 years) and present very few problems. If they are not well maintained, the units get gummed up, seem to always have problems, and do not run efficiently. In our experience, the life span can be cut to 10 or 15 years if they are not maintained.

Looking for an easy way to take care of your fuel oil furnace maintenance? You can read about our service agreements here.

2. Change the Air Filter Regularly

Filters are found on any ducted system, and fuel oil furnaces are no different. Remember to change your filter once every 3 months, or as recommended by your local professional (more or less depending on your specific lifestyle and household).

Not sure how to change your filter, what kind to use, or how often you should be changing it? Glance through this Beginner's Guide to HVAC Filters post.

3. Never Let the Fuel Oil Tank Get Low

Fuel oil collects dust and sediment, even when contained in a tank. When fuel oil mixes with dust, it creates a sludge that settles at the bottom of the tank. This sludge does not enter the furnace unless the fuel oil tank gets low enough, causing the filth and grime to get sucked up into the unit.

Do yourself a favor and just avoid that one... it's not a pleasant situation.

Fortunately, avoiding this issue is easy. Just keep tabs on the oil level after your first fill-up. Keep track of how often the furnace is running, and how much fuel it's going through. When it gets to half a tank, note how long it took to get there. If it made it through the winter on only half a tank, good news! you'll be all set to get annual fill-ups. If you made it through a few months, it may be worth getting the tank topped off a couple of times a year (once before the winter, and again 3 months later). Figuring out this schedule is very helpful for Fuel Oil owners, so the sooner you know when you usually need to get it filled, the better.

Also, note that the furnace will work harder and go through more oil during harsher weather, so if a particular week is excessively cold, check in on your oil levels to make sure you're still in good shape.


Fuel oil furnaces are a great, durable, long-lasting option for heating your home, but they do require some attention. If you're willing to devote some time now and then to make sure it's taken care of, that furnace will take care of you and your family for many cold winters to come.

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