What You Should Know about Your Oil Furnace or Oil Boiler—Part 2

Boiler room heating system

In our previous post, we took a closer look at some of the important functions of your oil heating system, including limit controls, primary controls and thermostats. We continue this here, with a focus this time on oil burner controls and switches.

Cad cell controls

Additional protection circuits, such as the cad cell (cadmium sulfide photocell sensors) were added to oil heat systems in the early 1970s. A cad cell, which is usually mounted on the burner, uses its photo cell “eye” to send a shutdown message to the primary control board if it cannot “see” the burner’s flame in about 45 seconds. Many cad cells made today feature 15-second safety timers.

Burner power switches

There are usually two switches that will cut off power to the burner. A red emergency switch is typically located at the top of the basement stairs. If the heating system is located in a utility room, look for the emergency switch near the room’s entrance.

A second burner power switch is often found on or near the heating system.

Important burner tip

Primary controls, which monitor the oil burner’s flame, have a reset button. This button allows you to restart the burner should a problem cause the unit to shut down. (For example, burners may need to be restarted after a power outage).

Pushing the button once should get the burner running, but if the safety switch shuts the burner down again, you should call for service. You should never push the reset button more than once because it might cause excess oil to be pumped into the combustion chamber. This will result in a lengthy and costly repair.