Oil Heater - How IT Works

How It Works

Oil heaters consist of metal columns with cavities, inside which oil flows freely around the heater. A heating element at the base of the heater heats up the oil, which then flows around the cavities of the heater by convection. The oil acts as a heat reservoir, with a relatively high specific heat capacity (approximately 2 kJ.kg−1.K−1) and high boiling point (approximately 150–300 degrees Celsius). The high specific heat capacity allows the oil to store a large amount of thermal energy in a small volume, while the high boiling point allows it to remain in the liquid phase for the purpose of heating, so that the heater does not have to be a high pressure vessel.

Using the oil as a heat reservoir, the heating element heats the oil, which remains warm for a long period of time while the heat is transferred to the metal wall through convection, through the walls via conduction, then to the surroundings via convection and radiation. The columns of oil heaters are typically constructed as thin fins, such that the surface area of the metal columns is large relative to the volume of the oil heat reservoir. A large surface area allows more air to be in contact with the heater at any point in time, allowing for the heat to be transferred more rapidly from the heater into the room.