Heating oil is any liquid oil or gas used for heating; specifically, fuel oil. In most cases, it refers to lower viscosity grades of heating oil often used in furnaces and boilers to produce home heating oil which is then used in commercial buildings for heating appliances such as boilers and central heating. Today, heating oil has developed to the point where there are numerous types of heating oil products on the market that are each suited to a specific application. Some heating oils are even more specialized and are used only for specific applications.
A heating oil burner is a device that heats up natural gas or liquid fuel oil for use in a heating system. These units are often a part of an air-source heating system. There are two types of heat exchangers: direct and indirect heat exchangers. The indirect heat exchanger changes heat from one fluid into another through a heat exchange membrane, while the direct heat exchanger changes heat from one fluid to another via an exchanger plate.