<P> Several efficiency metrics can be measured in regard to heaters, such as the efficiency of heating a room with a given amount of power, and the efficiency of the electrical generator which powers the heater and power loss from transporting the electricity over power lines . Measures may also consider how well a heater keeps the temperature of a space above a certain point . Such a measure would find inefficiencies in heating an already warm room . Many heaters (the majority of available models) are equipped with a thermostat to prevent this inefficient heating, which in turn reduces running costs . This feature was much more common in oil heaters than in the cheaper fan heaters until recently; thus many older oil heaters will be cheaper and more efficient to run than their contemporary fan heaters that lack the thermostat . </P> <P> Typical oil heaters range in power consumption / output from 300 to 2400 watts, and their length and number of columns is roughly proportional to their power rating . A 2400 watt oil heater is usually approximately 1 meter (3.3 feet) in length . </P> <P> All electric resistance heaters are 100% efficient, with operating costs determined by their wattage and the length of operating time . A 500 watt heater will take twice as long to reach the same thermostat setting as a 1000 watt unit; the total consumption of electricity is the same for both . </P> <P> By contrast, an electrical heat pump used for home heating typically has an efficiency well above 100%, expressed as its coefficient of performance . </P>

Does an oil heater dry out the air