What You Should Know about Your Oil Furnace or Oil Boiler—Part 1

The proven reliability of modern oil heating controls has been an important factor in making today’s oil a remarkably safe and efficient fuel for heating homes in New Jersey and throughout the Northeast.

A wide range of limit controls, thermostats and switching relays are used in oil heat systems. They have become more accurate and sophisticated with the introduction of more technologically advanced equipment. Here’s a brief overview of some of the controls to help you better understand how your oil heat system works.

Home heating thermostat


When heat is needed, the thermostat starts the burner through the primary control and an electrical circuit. The thermostat is the control that gets all of the other controls on an oil heat system going. When the thermostat sends a signal for heat, it triggers a series of subsidiary controls.

Today, many people are using a smart thermostat in their oil-heated homes. A Wi-Fi enabled thermostat allows you to view and change temperature settings, check local weather conditions and more, all from your smartphone, computer or tablet.

Once the smart thermostat gets installed, you register it online. This enables access from any location. If you’re away from home, you can use your phone or tablet to adjust the temperature setting so your home is at the perfect temperature when you return.

Limit controls

Limit controls on oil heat systems regulate warm air, water temperature and pressure control. There are two categories: high limit/safety controls and low limit/operating controls.

High limit/safety controls: These controls act as safeguards to prevent overheating. They will turn off the burner if temperatures become too high in the furnace or boiler, or if the pressure in a steam boiler rises to an unsafe level.

Low limit/operating controls: These controls start and stop the burner on a signal from the thermostat or aquastat (a device that controls water temperature).

Primary controls

Primary controls monitor the oil burner’s flame. Solid-state controls and advanced microprocessor-based controls are very accurate. Primary controls also have a reset button that allows you to restart your oil burner.

We’ll tell you more about the reset button and discuss oil burner power switches in our next post.