An oil heater, also known as an oil-filled heater, oil-filled radiator, or column heater, is a common form of convection heater used in domestic heating. Although filled with oil, it is electrically heated and does not involve burning any oil fuel; the oil is used as a heat reservoir (buffer).
Oil heaters consist of metal columns with cavities inside, where heat-transfer oil flows freely around the heater. A heating element at the base of the heater heats the diathermic oil, which flows around the cavities of the heater by convection. The oil has a relatively high specific heat capacity and a high boiling point. The high specific heat capacity allows the oil to effectively transfer thermal energy from the heating element, while the oil's high boiling point allows it to remain in the liquid phase for heating, so that the heater does not have to be a high-pressure vessel.[ citation needed ]
The heating element heats the oil, which transfers heat to the metal wall through convection, through the walls via conduction, and then to the surroundings via air convection and thermal 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 amount of oil and element that provides the warmth. 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 effectively, which results in a surface temperature that is safe enough to touch. The relatively large specific heat capacity of the oil and metal parts means this type of heater takes a few minutes to heat up and cool down, providing short-term thermal storage.[ citation needed ]
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Although oil heaters are more expensive to run and provide far less spatial heating than gas heaters, they are still commonly used in bedrooms and other small or medium-sized enclosed areas. This is because gas heaters, especially without a flue, are not suitable for bedroom use; gas heaters cannot be used in confined spaces due to the reduced oxygen and emissions produced. This leaves electrically powered heaters, such as oil heaters, fan heaters, and heat pumps, as the only alternatives.
Several efficiency metrics can be measured about heaters, such as the efficiency of heating a room with a given amount of power, the efficiency of the electrical generator that powers the heater, and the power loss from transporting the electricity over power lines. Measures may also consider how effectively a heater keeps the temperature of a space above a certain point. Such measures 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 cheaper fan heaters until recently, and because of this, many older oil heaters will be cheaper and more efficient to run than their contemporary fan heaters that lack a thermostat.
Typical oil heaters range in power consumption and output from 500 to 2,400 watts, with their length and number of columns being roughly proportional to their power rating. A 2400-watt oil heater is usually approximately 1 meter (3.3 feet) in length. Operating costs are generally calculated based on a linear relationship between the heater's wattage and the duration of operation. [1] A 500-watt heater will take at least twice as long to reach the same thermostat setting as a 1000-watt unit; however, the total electricity consumption will be the same for both. Additionally, the rate of heat flow from a heater to the air directly in contact with it is higher when there is a greater temperature difference between the two.
All electrically resistant heaters are 100% efficient at converting incoming electric energy into heat. However, since most of an oil heater's main electricity is produced by coal, oil, or gas generators with ~30% efficiency, electric heat is often less efficient and more expensive than combustion heaters (which directly convert oil or gas to heat). [2] By contrast, an electric heat pump used for home heating typically has an efficiency well above 100%, expressed as its coefficient of performance, [3] because it moves outside heat into a room rather than generating it.
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The primary risks of oil heaters are fires and burns. In both regards, they are generally more dangerous than heat pumps, hydronics, and air conditioning, but less dangerous than electric fan heaters or bar radiators, due to the surface temperature of any given type of heater.
Most modern small heaters have some form of tilt sensor to cut power if they are knocked over or placed on an unstable surface, which can reduce the risk of fire if a heater is knocked over.
From a safety standpoint, it is best to avoid having any object within three feet of an oil heater, and modern manufacturers do not recommend using an oil heater for drying clothes. Despite the average surface temperature of the heater in normal operation is considerably low, the extra thermal resistance of clothing on the heater can cause its surface temperature to rise to the material's autoignition temperature. Some oil heaters contain strong warnings to avoid operation in damp areas (such as bathrooms or laundry rooms) as moisture and humidity can damage components of the heater itself.
Oil heaters have been known to explode when their thermal fuses fail to trigger a shutdown, [4] which can cause fire, thick black smoke, unpleasant odors, oil on walls and other surfaces, and disfiguring scalding.
Some companies offer oil heaters with a fan to increase the quality of airflow over the heater. As it is constantly bringing the colder air from the room into contact with the heater, this can improve the rate of heat flow from the heater and into the room.
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.
A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint.
Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated to steam have many uses.
Solar water heating (SWH) is heating water by sunlight, using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions in different climates and latitudes. SWHs are widely used for residential and some industrial applications.
A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning systems, which can both cool and warm interior spaces.
A storage heater or heat bank (Australia) is an electrical heater which stores thermal energy during the evening, or at night when electricity is available at lower cost, and releases the heat during the day as required. Alternatively, solar storage heaters are designed to store solar energy as heat, to be released during the night or other periods where it is required, often making it more cost effective than selling surplus electricity to the grid and buying it back at night.
Induction cooking is performed using direct electrical induction heating of cooking vessels, rather than relying on indirect radiation, convection, or thermal conduction. Induction cooking allows high power and very rapid increases in temperature to be achieved: changes in heat settings are instantaneous.
A heating element converts electrical energy into heat through the process of Joule heating. Electric current running through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is independent of the direction of current.
A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a steam turbine connected to an electrical generator. The low-pressure exhaust from the turbine enters a steam condenser where it is cooled to produce hot condensate which is recycled to the heating process to generate more high pressure steam. This is known as a Rankine cycle.
Electric heating is a process in which electrical energy is converted directly to heat energy. Common applications include space heating, cooking, water heating and industrial processes. An electric heater is an electrical device that converts an electric current into heat. The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy. Most modern electric heating devices use nichrome wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators.
A fan heater, also called a blow heater, is a heater that works by using a fan to pass air over a heat source. This heats up the air, which then leaves the heater, warming up the surrounding room. They can heat an enclosed space such as a room faster than a heater without a fan, but like any fan, create a degree of noise.
Underfloor heating and cooling is a form of central heating and cooling that achieves indoor climate control for thermal comfort using hydronic or electrical heating elements embedded in a floor. Heating is achieved by conduction, radiation and convection. Use of underfloor heating dates back to the Neoglacial and Neolithic periods.
A space heater is a device used to heat a single, small- to medium-sized area. This type of heater can be contrasted with central heating, which distributes heat to multiple areas.
A convection heater is a heater that uses convection currents to heat and circulate air. These currents circulate throughout the body of the appliance and across its heating element. This process, following the principle of thermal conduction, heats the air, reducing its density relative to colder air and causing it to rise.
An infrared heater or heat lamp is a heating appliance containing a high-temperature emitter that transfers energy to a cooler object through electromagnetic radiation. Depending on the temperature of the emitter, the wavelength of the peak of the infrared radiation ranges from 750 nm to 1 mm. No contact or medium between the emitter and cool object is needed for the energy transfer. Infrared heaters can be operated in vacuum or atmosphere.
Radiators and convectors are heat exchangers designed to transfer thermal energy from one medium to another for the purpose of space heating.
HVAC is a major sub discipline of mechanical engineering. The goal of HVAC design is to balance indoor environmental comfort with other factors such as installation cost, ease of maintenance, and energy efficiency. The discipline of HVAC includes a large number of specialized terms and acronyms, many of which are summarized in this glossary.
Tankless water heaters — also called instantaneous, continuous flow, inline, flash, on-demand, or instant-on water heaters — are water heaters that instantly heat water as it flows through the device, and do not retain any water internally except for what is in the heat exchanger coil unless the unit is equipped with an internal buffer tank. Copper heat exchangers are preferred in these units because of their high thermal conductivity and ease of fabrication. However, copper heat exchangers are more susceptible to scale buildup than stainless steel heat exchangers.
A storage water heater, or a hot water system (HWS), is a domestic water heating appliance that uses a hot water storage tank to maximize water heating capacity and provide instantaneous delivery of hot water. Conventional storage water heaters use a variety of fuels, including natural gas, propane, fuel oil, and electricity. Less conventional water heating technologies, such as heat pump water heaters and solar water heaters, can also be categorized as storage water heaters.
The Glossary of Geothermal Heating and Cooling provides definitions of many terms used within the Geothermal heat pump industry. The terms in this glossary may be used by industry professionals, for education materials, and by the general public.