Infrared heating and space heaters – new in seasonal heating

Recommendation points

• Infrared heating – history
• The principle of operation and types of infrared heaters
• How does infrared radiation affect humans
• Infrared heaters – how to choose them

In this Article: The History of Infrared Heating the principle of operation of infrared heaters; their types and characteristics; is infrared radiation dangerous to humans; how to choose infrared heaters.

Since ancient times, man has known that along with the setting sun, heat also leaves, the cold of the night makes him shiver chilly and look for sources of heat. For thousands of years, the main supplier of heat was an open fire, after that central and individual heating systems, various electric heaters appeared in our homes … But all these heat sources have one common drawback – they dry the air, unceremoniously removing moisture and forcing homeowners to purchase not only the heaters themselves, but also humidifiers. And yet there is one type of heaters that does not dry out the air for the reason that it does not heat it up – these are infrared heaters, the principle of which is borrowed from the Sun itself..

Infrared heating – history

Infrared radiation itself was discovered and studied by the English astronomer and composer William Herschel. 220 years ago, this astronomer decided to find out which color of the solar spectrum warms up the telescope he created the most. He decomposed the sunbeam into its components using a prism and, measuring the temperature with a thermometer, found that most of all the temperature rises beyond the edge of the red light ray. Herschel concluded that behind the visible red part of the spectrum there is some kind of invisible radiation, which heats objects the most..

William Herschel (Friedrich Wilhelm Herschel). 1738-1822

The creator of the first infrared heater, the energy source for which was gas, was the German inventor Gunter Schwank – in 1933 he received a patent for this invention. In Russia, as early as 1905, infrared heating was attempted by its inventor – engineer V.A. Jachymovich, however, according to his project, the bearer of radiant energy was hot water and steam, transmitted through the building by steel pipes embedded in the walls, ceilings and columns..

The first infrared heat emitters were produced mainly for technical needs – they are still widely used for drying painted surfaces, with their help they sterilize and dry food.

The principle of operation and types of infrared heaters

If most of the popular heating devices and systems are based on convective heat exchange, in which the air is first heated, which in turn heats the walls, ceiling, floor and objects in the room, then radiant heat transfer is characteristic only of infrared heaters.

Infrared radiation includes three ranges of electromagnetic waves: 0.77-15 microns – short-wave; 15-100 microns – medium wave; 100-340 microns – long-wave. Due to the spectral proximity of the short wavelength range to visually distinguishable light and the almost coincidence of the long wavelength range with ultrashort radio waves, infrared radiation behaves like visible light (projected in a straight line, refracted and reflected) and, like radio waves, penetrates through some materials impervious to light. In other words, this type of radiation cannot heat translucent media like air, and heats those objects that are impenetrable to the visible spectrum of sunlight. The efficiency of heating with long-wave infrared rays is clearly demonstrated by the Sun, which has been heating the Earth for billions of years with these rays..

Any infrared heater is based on the principle of radiant heating – the resulting infrared rays are reflected by a reflector into the heating zone. Gas, diesel and electric infrared heaters are available depending on the energy source. In the first version, a mixture of air with propane is ignited using a piezoelectric element, such heaters are intended for open spaces, such as sports grounds and park areas – gas infrared heaters emit long waves, heating an area of ​​about 25 m² (depending on model).

The second version of the IR heater is also intended for open spaces and rooms, but it works on the principle of a heat gun and is easy to move – its design, in addition to a filled tank with fuel, requires an electrical connection. Its principle of operation: when the power supply is applied, the burner electrodes are heated; the fuel pump and the fan are started, forming the fuel-air mixture; the mixture of fuel and air vapors entering the burner ignites, emitting infrared rays.

It should be noted that only infrared radiation can effectively heat open spaces, regardless of drafts.!

The third version of the infrared heater operates on electricity, the source of radiation is a filament coil enclosed in a base, which heats up to a temperature of 900 ^aboutC. The resulting infrared rays, as in the design of gas and diesel heaters, are directed to the heating zone using a reflector.

Externally, a gas infrared heater resembles a classic street lamp – a cylindrical base to which gas is supplied or in which a gas cylinder is placed, a rack, inside it is a hose connecting the gas source and the burner. The design is completed by an injection burner, above which a radiator reflector is located. The efficiency of such heaters is quite high – 80-85%, the heated area is about 25 m². The average cost of gas infrared heaters is 16,000 rubles.

A diesel infrared heater consists of a frame equipped with a wheelbase, a fuel tank (diesel fuel or kerosene) mounted on it, and a radiator body that looks like a horizontally directed searchlight, connected by hoses to a fuel tank. The average price for a diesel infrared heater is 18,000 rubles.

Electric infrared heaters are equipped with three types of emitters, differing in the shell in which the filament is placed – quartz, ceramic or metal (usually aluminum). Infrared heaters of simple design are equipped with a vacuum tube made of transparent quartz glass with a filament located inside, therefore such heaters are cheap (from 2,000 rubles). Cons of such emitters: short service life – about 2 years; relatively high power consumption – about 1-2.5 kW; a reddish glow perceptible to the human eye, unpleasant for sensitive eyes. Short-wave infrared rays emitted by such tubes are not suitable for heating for a long time, they are convenient for quickly warming up a room or for rooms of a large area.

The spiral in ceramic infrared heaters is hidden inside the shell and is not visible, i.e. no glow is noted. The service life of ceramic emitters is higher – from 3 years, but they are more expensive (from 9,000 rubles). Plus, ceramic infrared heaters are less, compared to quartz emitters, the need for electricity is in the range of 50 W-2 kW (depending on the specific model). The slow heating and cooling of ceramic infrared emitters is compensated by their durability; they are used in infrared saunas and hospitals.

In terms of their characteristics, radiators with a heating coil inside a metal case are similar to ceramic heating elements, the cost of infrared heaters with such radiators is slightly higher – about 11,000 rubles. All flat heaters are equipped with radiators in a metal housing.

According to the heating temperature of the emitting plate, infrared heaters are divided into high-temperature (more than 400 ^aboutC) and low-temperature (in the range of 25-50 ^aboutFROM). Heaters with radiant plate heating within 100-200 ^aboutC is called longwave. The infrared wavelengths of high-temperature heating devices are too short – less than 7.5 microns, they are “hard” and, with prolonged exposure, will cause damage to human skin comparable to a sunburn. Therefore, such emitters are used only in places of short-term stay of people, for example, in the premises of workshops. Low-temperature heaters, safe for human skin, are used everywhere, they are made in various forms, including in the form of flat panels placed on the ceilings of offices and residential premises. IR heating devices with long-wave radiation are more often used in residential premises with a ceiling height of up to 3 m; their radiation is safe for human skin. In living quarters where children are accommodated, the highest heating temperature of the spiral of an IR emitting element should not exceed 65 ^aboutFROM.

Infrared heaters can be configured to work in automatic mode and become part of the smart home equipment. This is especially convenient for country houses that are empty in the cold season – you can exclude a drop in temperature inside residential premises by setting IR heaters to maintain the temperature in them at an optimal level of 5 ^aboutFROM.

How does infrared radiation affect humans

In general, infrared radiation is safe for humans – moreover, it improves overall well-being. But it should be borne in mind that the direct effect of the radiation of an infrared heater is similar to the irradiation of the sun’s rays, to be under which on a summer afternoon without the protection of a headdress is fraught with overheating. On a fine day in the sun, thermal radiation acts with an intensity of about 400 W / m² – heatstroke is inevitable. Heating by infrared radiation with an intensity of over 150 W / m² dangerous to humans, because can weaken the immune system, disrupt the structure of protein molecules. Optimal for an adult will be infrared radiation, whose intensity is in the range from 60 to 100 W / m².

Avoid short-wave infrared heaters that can penetrate the human body. Long-wave infrared emitters are generally safe, but they must be installed strictly at the height declared by the manufacturer – the shorter the distance to the irradiated surface, the higher the radiation intensity reaches it. If a feeling of discomfort arises when walking or sitting under an IR heater, its radiation intensity should be reduced. From this point of view, it would be correct to install several low-power heaters than one, but high power..

With regard to diesel and gas infrared heaters, one rule must be strictly observed – place them only in the open air.!

Infrared heaters – how to choose them

First of all, the IR heater is not as exotic as it seems at first glance – in the USSR there were such household appliances that outwardly resemble a round bowl of a radar installation. A round, concave reflector, in the center of a ceramic cone, around which a bare heating coil is wrapped, when turned on, it warms up red-hot – remember?

Such infrared heating devices have not been produced for about 15 years – they are frankly dangerous, tk. can lead to a fire, not to mention burning oxygen.

Studying modern types of electric infrared heaters, let us consider in detail two of them – with a heating element in a quartz tube and in a metal case. A quartz tube has only one advantage – the efficiency of such a heater is slightly higher than that of a metal plate radiating heat, by about 5%. The heating temperature of the coil inside the quartz tube exceeds 600 ^aboutC, the heat flux emitted by it is strong enough – for this reason, such infrared emitters are installed on shawarma braziers. As mentioned above, the service life of a quartz tube is short, and replacement will cost a lot – the cost of a quartz tube is a significant part of the price of the heater itself..

IR heaters with a low-temperature spiral-heating element inside an aluminum plate (heat-emitting element) do not heat up above 300 ^aboutC, their only “working” minus is a quiet crackle – stainless steel forming a spiral and aluminum have different expansion coefficients, this is normal and should not cause concern. Carefully study the internal structure of such a heater, finding out the characteristics of the heating element, thermo-radiating plate, housing, insulator and foil.

So, we ask the seller to remove the outer cover from the heater, carefully study its internal structure and ask the seller questions:

• What is the thickness of the anodizing layer on the thermo-radiating plate? High-quality anodizing layer should be at least 25 microns. A layer of this thickness will provide about 20 years of proper operation of the device, with a smaller layer, the plate will burn out in three years, the heater, accordingly, will fail. Unfortunately, it is impossible to externally determine the thickness of the anodizing layer – you will have to trust the seller;
• What metal is the heating element made of? Heating elements can be made of stainless steel or ordinary ferrous metal; in the second version, the heater can be installed only in dry rooms (the balcony and garage are not such);
• carefully examine the inside of the metal case, it will not be painted here – this is normal. Make sure that there are no traces of rust on the metal, if there are any, refuse to buy – it means that the outside of the metal was painted with rust, which in a couple of years will appear on the outside, spoiling the appearance of the device;
• What is the thickness of the reflector foil? The minimum allowable thickness is 120 microns, if the foil is thinner, then a significant part of the infrared rays will go to the ceiling and will not be reflected in the desired direction. Use a regular ballpoint pen – remove the cap and lightly press on the foil (the pressure when pressing is the same as when setting a point on a paper sheet). Jamming or the appearance of a hole in the foil means that its thickness is no more than 100 microns – pressing on a foil with a thickness of 120 microns will leave almost no trace.

By the way, the presence of a fan in the design of an infrared heater means not an advantage, but a disadvantage – in fact, it will be an ordinary convection heater that raises dust in the room.

Make sure that the IR heater itself and its packaging are correctly and fully labeled – glossy factory stickers (matte stickers can be made on a regular laser printer), clearly printed text, the manufacturer is indicated, compliance with GOST or TU, the date of issue is indicated. Be careful with the warranty period – too short or too long a period with an unknown brand of the manufacturer should inspire suspicion.