An oil furnace, also known as an oil-fired furnace, burns oil as its fuel source to produce hot air which is used to heat buildings. Here are the key things to know about oil furnaces:
• Uses oil as the fuel. Oil furnaces burn oil, typically #2 heating oil, to generate hot air for heating. The oil is stored in an external tank and pumped to the furnace. Oil is a non-renewable fossil fuel.
• Less common than gas furnaces.
Oil furnaces are less popular than gas furnaces which burn natural gas. There are fewer oil furnaces manufactured and installed compared to gas furnaces.
• Requires an oil burner. An oil burner is like a small internal combustion engine that burns the oil to heat air which then passes over heat exchangers to be distributed in the home. The oil burner circulates oil from the tank to the furnace.
• Requires a forced draft fan.
It uses a fan to force combustion gases over tubes/heat exchangers to maximize heat transfer for efficiency. The fan ensures even and complete burning of the fuel oil.
• Tend to be less efficient than gas furnaces.
Although its efficiency has improved, oil typically has lower energy density than natural gas so oil furnaces often require a larger size to achieve the same heating output, resulting in slightly lower efficiency.
• Higher maintenance needs.
Oil furnaces require more maintenance than gas furnaces like annual tune-ups, filter changes, draining/flushing fuel lines, cleaning burners/chimneys, etc. The oil burner also requires periodic adjustment and cleaning. Maintenance helps prevent excess pollutants and ensures safe, efficient operation.
• Can require an oil filter, preheater and tank.
It removes impurities from the oil before it enters the furnace. A preheater warms the oil for easier burning in cold weather. An oil tank is the exterior container that holds the heating oil fuel for the furnace.
• Can be single-stage or two-stage.
A two-stage oil furnace has two burners that can run at a lower capacity for more even, efficient heating or at full capacity for maximum heat output. Two-stage furnaces tend to be more efficient but also more expensive. Single-stage furnaces simply run at full or off.
• Can last 15-25 years with good maintenance.
An oil furnace lifespan depends on quality, maintenance and burn hours. Well-maintained, high-efficiency oil furnaces can last 20 years or more. Lack of maintenance and repair will significantly reduce lifespan.