Infrared film heaters

In winter, in Russia, housing must be heated even in the southern regions, which determines the demand from our consumer for many types of stationary and portable heating equipment. An extensive niche in the Russian market of heaters offered by foreign and domestic manufacturers is occupied by a group of infrared devices with a common principle of influencing the environment, but consisting of subgroups that differ in design and, as a result, functionality and efficiency.

Let us consider in more detail one of the types of infrared devices for heating homes — a wall-mounted film heater, which is used in everyday life relatively recently, but, due to a number of advantages, is already in stable consumer demand.

The principle of operation of IR heaters

Infrared rays are invisible electromagnetic waves with a length of 0.74 microns to 1.5-2 mm. Any heated body becomes a source of infrared radiation — an emitter, and the emitter is heated by converting into heat the energy of one of the types of energy carrier — electric current, gas, solid or liquid fuel.

Infrared radiation, encountering an obstacle in the path of propagation, causes vibration of its surface layer with an increase in the speed of movement of molecules, which causes an increase in the temperature of the object to a certain depth.

The infrared wavelength range, in turn, is divided into the following components:

• shortwave — 0.74-2.5 microns;
• medium wavelength — 2.5-50.0 microns;
• long-wave — 50.0-2000.0 microns.

The intensity of heating the surface of objects depends on the temperature of the emitter — the higher it is, the shorter the wavelength of infrared radiation and the surface of the obstacle is heated to a greater depth. During propagation, IR rays do not change the temperature characteristics of the transit medium — the air is heated not from their passage, but due to the transfer of heat to it by heated objects.

The method of heat transfer through infrared radiation is not related to thermal conduction or convection, so IR heaters are able to transfer heat even through a vacuum.

The device of the film electric heater (PLEN)

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All IR heaters are divided into high-temperature shortwave and low-temperature longwave. Film-type heaters belong to the second group.

Visual Film IRelectrothe heater is a flexible sheet or strip of a certain format. If the model is not decorative (heater-painting), then the transparent outer layers allow you to see the location of the components.

Important! PLEN is an acronym meaning «film radiant electric heater» and not a trademark registered by anyone.

Structurally, any kind of domestic film-type heater includes the following components:

• resistive type heating elements — made of carbon-containing materials or metals, tape or plate, capable of heating up to 35-55 degrees when an electric current passes through them;
• heat-distributing base — one or two layers of thin aluminum foil, on which resistors are mounted, for uniform distribution of heat from their heating over the screen surface;
• thermostat with temperature sensors;
• two protective layers of a laminating film with a melting point of up to 210 degrees, between which there is a foil with heating elements;
• cable for connecting PLEN to the network.

The total thickness of the heating sheet does not exceed 1.5 mm.

Schematically, the PLEN can be depicted as follows (the thermostat is installed separately):

1 — contacts for connecting the device to a 220 V network;

2 — a flexible two-layer shell made of a polymer film on a supporting lavsan or polyester base;

3 — points of industrial, carefully insulated connection of the supply wire with the contacts of the heaters (self-replacement of the cable is not provided);

4 — heating resistive elements (tape or individual plate, connected by conductors);

5 — aluminum foil;

6 — hologram to protect the heater from counterfeit production.

The principle of operation of the PLEN

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When the power cable is connected to the network, the resistive elements heat up to the pre-set temperature value (35-50 degrees) within 10 seconds. Film heaters for non-domestic purposes (for mini-saunas, dryers of agricultural products), used in rooms with a ceiling height of more than 3.5 m, have resistive elements of wire, tape, plate execution made of nichrome, fechral or multicomponent alloys in the design, providing a higher temperature heating.

The heat of the heaters is transferred to the foil and, due to the high thermal conductivity of aluminum, is evenly distributed over its surface, which allows the heater to generate infrared radiation of equal intensity over its entire area. When the air in the room reaches the set temperature value, the film heater is switched off by a signal from the temperature sensor in the thermostat, and the objects heated by radiation continue to give off heat. When the temperature in the room drops by 1 degree, the thermostat will turn on again, and the film heater will perform a new cycle of operation for radiation.

A correctly calculated combination of the material of the reflective layer, its thickness, and the layout of resistive heaters ensures the conversion of electricity into heat, and then into infrared radiation with a wavelength of 8-15 μm that is favorable for human perception.

Important! With an increase in current strength or failure of the thermostat, the temperature of resistive graphite heaters will increase, which will lead to their destruction and failure of the household film heater as a whole, that is, the resistive elements also perform the protective function of fuses.

Varieties of film heater

One of the main differences between film-type electric heaters is their format and dimensions. PLENs are produced in the form of tapes of various lengths and widths. Self-correction of the dimensions of such films is impossible, therefore, PLENs are produced in a wide range of dimensions, allowing you to choose the best option. The most common are three sizes of tapes in width: 35, 51 and 65 cm.

Films with a width of 35 and 51 cm have two zones, free from the location of resistive elements and intended for installation with a stapler — along the edges. Ribbons 65 cm wide have three such zones — two along the edges and one along the middle (as an option — two along the edges and between them transverse with a certain step).

Flexible film IR heaters can be installed both on vertical and horizontal surfaces — the design of film-type electric heaters does not depend on the place of its installation, with the exception of PLEN-paintings, which, by definition, should be located in places of the best view — on the walls. The classification of a certain film heater as a wall, floor or ceiling device is determined only by the design location of its location — an important factor affecting the efficiency of this IR device. Thus, a film heater on the wall, after installation on the ceiling, in everyday life turns into a ceiling heater.

Consider the options for placing PLENs in the premises in order of increasing efficiency of their use.

Wall arrangement of film heaters

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Placing PLENs on the wall is the least effective due to the limited sector of IR radiation exposure to building envelopes — most of the infrared rays heat the wall surface opposite, almost without affecting the floor and ceiling.

Fixed film devices mounted on the wall are effective as the main means of heating only if the opposite base has a significant area — then the heat transfer from its heated surface into the air will be quite noticeable.

If the area of ​​film heaters installed on the wall is not significant, and the base, on the contrary, also has window openings, then the efficiency of such an IR heater will be low. But stationary wall-mounted film heaters of a small area are convenient as an additional means of heating — to increase the comfort of the temperature regime of a certain place or zone in a room.

A variety of film-type wall heaters are portable IR devices with artistic design that imitate paintings. In order for their use to be rational and effective, heater paintings should be used in small rooms for heating, for example, a workplace, or in groups, the total heat transfer area of ​​​​which will be commensurate with the size of the room.

Floor placement of film-type IR heaters

Infrared radiation from devices placed in this way affects the floor and ceiling. The warm surface of the floor increases the comfort of human contact with it — you can walk without shoes, sit or lie on the floor, etc. In addition, the transfer of heat from the floor to the cold lower layers of the air in the room is also heating the room, as it causes the occurrence of convective currents. But the energy of that part of the IR rays that penetrates the floor covering is spent on heating the ceiling, which is less efficient — the ceiling base does not need much, since its temperature is already quite high as a result of convection.

Important! It is not advisable to place infrared film heaters in furniture locations — bulky objects made of materials with a low thermal conductivity create barriers to infrared radiation.

Ceiling installation of infrared film heaters

When using film-type heating devices as the main means of heating, placing them on the ceiling is the most effective, since such an arrangement provides exposure to radiation on all enclosing structures of the room, regardless of configuration, and objects located in it.

Important! When choosing the ceiling for the installation of PLENs, it must be taken into account that the efficiency of heating with IR rays decreases with increasing distance to the emitter. Film-type infrared heaters are low-temperature long-wave devices, so their use with a ceiling height of more than 3.5 m is irrational.

The advantage of ceiling placement of PLENs, in addition to high heating efficiency, is the minimal risk of accidental damage to the heater, located at a sufficiently safe distance from the traffic area. However, there are also disadvantages — the location on the ceiling makes the PLEN vulnerable to leakage from above, and installation work at a height is more time consuming.

Characteristics of an electric heater of a film design.

When choosing a film IR heater, it is necessary to be guided not only by its size — PLENs also have other characteristics, including those that are important for specific conditions:

• the voltage of the consumed current is mainly 220 V, but they are also produced for 110 V;
• power — up to 500 W, energy consumption per square meter of a film heater (specific power) can be from 70 to 170 W;
• maximum heating temperature — 35-50 degrees;
• current consumption — 0.7-1.2 A;
• specific gravity — up to 350 g / m2.

For clarity of description, we summarize the data on the characteristics of film heaters with reference to their standard sizes:

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Installation of film-type infrared heaters

The installation of flexible film heaters, regardless of the place of installation, does not require the performer to have high-class professional skills, but must be carried out in compliance with the following rules:

• the installation site of the PLEN must be flat and dry;
• cutting of rolls, if provided for by the model, should be carried out only according to the markup specified by the manufacturer;
• checking the performance by turning on the heater folded into a roll is prohibited;
• the length of one strip film fragment should not exceed 8 m;
• adjacent strips of the heating system are located at a distance of at least 5 mm;
• bending the PLEN at an angle of more than 90 degrees is not allowed;
• installation of the film to the base is carried out with brackets using a construction stapler or special fasteners (the use of ordinary nails and self-tapping screws is not effective);
• it is forbidden to carry out installation work at sub-zero air temperatures — after warming up the room, the film strips will increase in size and form folds.

The sequence of installation of film IR heaters

The base for the placement of PLEN to protect against overheating should be equipped with a foil reflective screen that acts as a heat and water insulator, for example, penofol, isolon.

The protective coating is mounted on the base with an overlap of adjacent edges of 3-5 cm on each other; to speed up the process, it is advisable to use special fasteners for fastening, which are available in a wide range on sale.

From above, the joints of the screen strips are glued longitudinally with special foil tape.

On top of the laid screen, elements of the film heater are mounted — after preliminary layout and in accordance with the installation instructions attached to the device. Installation is carried out taking into account the rule — there should be 8-10 fasteners per 1 square meter of flexible film.

When the installation of the heating circuit is ready, it is connected to the thermostat, which should be located at a height of 1-1.5 m from the floor, and the system is checked for operability.

In addition, for correct monitoring of the temperature regime in the room, the thermostat must be located away from other heating devices, have a heat-insulating gasket underneath, and be protected from direct sunlight and drafts.

If the test results of the IR device are positive, finishing materials are laid — a floor covering or a false ceiling, which are mounted with a gap of 10-15 mm between the cladding and the film.

Important! Absolutely transparent materials for PLENs do not exist — any finish on top of the film is a screen that attenuates radiation to one degree or another.

Read on the topic — how to fix, lay and glue penofol.

Separate remarks and recommendations for operation

• One should not expect high efficiency from film IR heaters, as well as from any other heating units, in the absence of thermal insulation of housing enclosing structures.
• The statements of marketers about the PLEN wavelength of 8 microns, supposedly optimal for human perception, do not correspond to reality — the radiation of IR heaters is always in a certain range and cannot consist of waves of any one wavelength.
• Installing PLEN in one room, even on the entire area of ​​the enclosing structures, will not solve the problem of heating other rooms for the house.
• The work of PLEN is not accompanied by a decrease in oxygen in the air of the room, so there is no need to increase the frequency of ventilation of the premises when using film heaters.
• It is not necessary to turn off the PLEN system for the summer period — it is enough to set the desired temperature on the thermostat.
• The durability of infrared film heaters declared by manufacturers (up to 50 years) is a hypothetical value, since PLENs began to be produced relatively recently.
• The safety requirements for household electrical appliances, including the film type, are set out in GOST R 52161.2.96-2006.

Conclusion

Film electric heaters are devices that have many advantages, but a significant part of the advantages of PLENs is inherent in most electric heating units. In order to objectively evaluate the information on the technical characteristics of these devices offered by sellers, it is necessary to have a clear understanding of the principle of operation of heating films. Many of the parameters declared by the PLEN implementers do not correspond to reality and are just marketing tricks. For example, about the low cost of installing infrared films compared to a water heating device based on a gas boiler — this is true only if the gas pipeline is far away.

The main essence of the article

1. Wall film electroThe heater is a modern efficient solution to the issue of space heating.
2. PLEN is an electrical appliance that emits infrared waves, therefore the principle of heating housing with this device does not differ from the effect of other types of IR emitters on the environment — heating objects and structures without changing the parameters of the transit medium.
3. The device of film electric heaters does not depend on the place of installation, therefore, the division of PLENs into wall, ceiling and floor devices, except for film-pictures, is due only to their planned location.
4. Installation of film infrared heaters is not very laborious, but failure to comply with installation requirements will lead, at a minimum, to low efficiency of their work, and even to damage to the device.
5. Knowing how PLENs work and the nuances of using PLENs will help to separate the true claims of manufacturers from the marketing techniques that are so common among non-tech-savvy sellers.