If you use an oil burner for a furnace, boiler or water heater in your Mid-Atlantic home, it’s not a bad idea to acquire a passing familiarity with how the system works. Some degree of understanding will leave you better equipped to troubleshoot malfunctions, determine the best way to save oil and energy, and be better informed if you have to tell an HVAC serviceman what’s wrong with your oil-fired appliance. Here are some basics of how an oil burner works. For any issue that extends beyond your knowledge, however, make sure you contact a reliable HVAC service company who works with oil burner systems.
How Oil Burners Work
As with most HVAC systems, an electric-powered switch or circuit must be engaged or “on” for the oil-fired furnace, water heater or boiler to start working. Electricity is provided via a safety control, likely called a primary controller.
The controller allows electrical power to run into an electric motor, which engages a motor shaft that begins rotating. That spinning shaft is positioned through the inside of the oil burner motor, where it’s connected to a rotating fan (sometimes called the squirrel cage fan but in this case, functionally, the blower for the oil burner) and the fuel pump. Modern high-speed motors for oil burners rotate at 3,450 rotations per minute (RPMs), while older models use slower motors that spin at 1,725 RPM.
The oil burner’s blower spins, pulling air for combustion through adjustable air intake slotted openings on the side of the oil burner.
The extension from the electric motor running the oil pump draws heating oil (most commonly No. 2 oil) from an oil tank located either inside or outside your home through a fuel line connected to the tank. In properly set-up systems, the heating oil will be pumped through both an external oil filter and internal screen filter and pressurized to at least 100 psi.
After the pressurized heating oil moves out of the oil pump through a high-pressure fuel line, it moves into the oil burner tube. This is where a special nozzle turns the liquid into a very fine spray. Sometimes, problems in the heating oil component may result in unusually loud operation, a loss of heating and other issues with your oil burner.
Igniting the Heating Oil
Just like with any combustion appliance, ignition is a vital step in how an oil burner works.
A transformer in the ignition system converts incoming 120-volt electrical power to a much higher voltage. That juice is sent to two electrodes that are connected to the nozzle assembly. The electrodes, which are very close to each other, produce a spark that’s right in the flow of the oil. This ignites the oil.
If the oil spray fails to ignite, in a properly operating oil burner system, safety controls will turn off the burner. This way, the non-ignited oil won’t continue being pumped into the system, something you want to avoid.
Actual Combustion
The spray of flaming oil heats the inside of the appliance – whether furnace, water heater or boiler – also called the combustion chamber. The combustion chamber is lined with a flame-resistant material that will get very hot. This material acts to protect the cast-iron or steel walls of your appliance from the burning oil. At the same time, the material is so hot that it ensures all of the oil that gets into the chamber will be combusted.
The Transfer of Heat
The scorching gases that result from combustion flow through the appliance’s heat exchanger, usually moving upward, where they transfer heat energy to the furnace, water heater or boiler, before continuing on their way to a flue pipe and ultimately outside through the chimney.
Again, as with any other central heating system, when the thermostat or other control senses that the desired temperature has been reached, the electricity to the oil burner will switch off, halting the electric motor, along with the combustion blower, oil pump and ignition transformer.
If you’d like further information about how an oil burner works, or to discuss energy-efficient options for heating your Mid-Atlantic home, please contact us at Griffith Energy Services, Inc. For more than 100 years, our team of professionals has provided quality service, including oil heating system delivery, installation and repairs, to homes in Maryland, Northern Virginia, Washington, D.C., and Delaware.
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