Oil heaters can also be known as column heaters, they are a form of convection heating for the domestic environment. These heaters consist of metal, usually steel with cavities running up and down the main profile; this allows for the oil inside to flow freely around the heater. It works by a heating element heating up the oil; this then flows around these cavities of the heater by means of convection. In fact the oil acts as a heat reservoir or buffer, having a relatively high heat capacity approx 150-300 degrees Celsius. The oils heat capacity allows it to store large amounts of heat in the form of thermal energy in quite a small volume. The high boiling point allows it to remain in liquid phase for the purpose of heating, so that the heater does not have to be a high pressure container. This system allows the heat to remain for long periods of time, the heat transferring to the metal surroundings and then on to the air it is supposed to be heating.