FAQ

General Questions

Heating With Infrared: Basic Questions

Questions On Use

Why do some infrared bulbs emit red light?

Infrared bulbs (also called red light lamps or heat lamps) emit infrared-A rays. These bulbs emit visible red light because the infrared area is directly adjacent to visible light. IR bulbs are used for medical purposes, for example.

Is infrared radiation dangerous for children, animals or the skin?

No. Humans are constantly exposed to infrared radiation, also known as “thermal radiation”. All objects warmer than 1 kelvin emit electromagnetic radiation, depending on their temperature. With rising temperatures on the surface, the intensity of the radiation increases and the wavelength becomes shorter. Most of this radiation remains within the infrared range up to approx. 600°C and is invisible to humans. If the temperature increases further, the radiation becomes visible and the colour of the glow shifts from fiery red to light red (850°C), then to yellow (1000°C) and, finally, to white (1300°C).
The proportion of harmful radiation - ultraviolet light, for example - increases only if surfaces exceed these temperatures further; this can result in a danger to humans. On the other hand, infrared heating devices that work in the invisible spectral range beyond the red light do not emit any harmful radiation.

See also:

Is there a danger of burns? What surface temperatures do IR heating systems reach?

DIN EN 60335-2-30 stipulates that temperature increases – based on the ambient temperature – of heating devices with metal surfaces cannot exceed 85 kelvin, and that temperature increases for devices with glass or ceramic surfaces cannot exceed 105 kelvin.

Thus, at a room temperature of 20°C, surfaces must not be any hotter than 105°C or 125°C.

Burn injuries are not caused if the heated surface is touched briefly. Nevertheless, we recommend limiting surface temperatures - in children's rooms, for example - depending on use of the device. There is no prescribed limit for heating systems installed at heights of more than 1.8 m that are not easily reachable.

Does IR heating generate electrosmog?

High-quality infrared heaters are practically free from electrosmog and fall below permissible maximum levels; thus, there is no harmful radiation exposure associated with them. Electrosmog is generated in small quantities only when systems have cable connections (supply cables), as with other household appliances.

Does heating with electricity make sense in the long term?

Gas and oil reserves are not infinite and are subject to major price fluctuations. The environmental impact of various other types of heating is well-known. Heating with electricity makes sense. Electricity can be obtained from wind or photovoltaic power, i.e. users can become energy-independent by generating their own electricity. Infrared heating systems, combined with green electricity (e.g. using photovoltaic systems) yield a CO2-neutral energy source and can result in household energy self-sufficiency. The increasing importance of electric vehicles, as well as the desire for more efficient energy use in “smart homes” also point towards the future significance of electric heating systems.

Is heating with electricity expensive?

Consumption cost comparisons indicate that heating with electric power appears more expensive in comparison to oil or gas due to the higher price per kWh. When costs relating to capital and operation are considered, however, infrared heating offers considerable economic advantages, particularly in buildings that require only a small amount of heat.

In old buildings, for example, when replacing old night storage heating systems, use of infrared heating results in lower levels of consumption due to the fact that it is easier to regulate. Whether it is possible to operate such systems economically depends to a large extent on the local tariffs in place for night storage heaters and direct electrical heating systems.

We always recommend comparing overall heating costs - capital, consumption and operation-related costs - in respect of the relevant heating systems before taking any specific action.

Are studies available on the durability of IR heating systems?

Some manufacturers conduct continuous stress testing and allow third-party monitoring. We are not aware of any official studies. Because infrared heaters do not contain moving parts, their lifespan is dependent only upon the temperature resistance of the materials used. Thus, their lifespan can far exceed 20 years.

What is infrared (IR) radiation?

We come into contact with infrared (IR) radiation every day in the form of sunlight. In physical terms, IR radiation is an electromagnetic wave located below the red end of the light. It spreads across open spaces at a wavelength of 780 nm to 1 mm. All warm objects emit infrared radiation. The hotter the surface, the shorter the wavelength and the more intensive the radiation. Distinction is made between A, B and C radiation, depending on the wavelength. When the temperature rises, the heat radiation's spectral peak shifts towards shorter wavelengths up to visible light. If infrared radiation comes into contact with our skin, we feel it as heat. This effect can be applied to heating.

Infrared-A:
Short wave emitters, also called “infrared emitters” have a surface temperature of at least 900°C. They light red, require practically no warm-up time and contain a radiation proportion of over 90%. Drafts and wind have little impact on radiant heat. The emitters, therefore, are ideally suited to outdoor use.
Infrared-B:
Medium wave infrared emitters emit infrared radiation between 1400 nm and 3000 nm and have a surface temperature of 300 to 900°C. They do not generate light and, consequently, are also called “dark radiators”. Medium wave infrared emitters are used where there is increased demand for heat in enclosed spaces.
Infrared-C:
Long wave infrared emitters have a surface temperature of up to 200°C, with surface temperatures of approx. 100°C on walls and up to 200°C on ceilings. The term “infrared heating” emerged due to the fact that the spectral peak lies within the infrared range. Infrared heating is ideally suited to residential heating.

What is radiant heat, or thermal radiation?

In the event of a difference in temperature between two objects not isolated from one another, heat flows from the higher to the lower temperature until the two different temperatures have equalised. Distinction is made between three types of heat transmission in physical terms:

Thermal radiation - also known as “radiant heat”

Heat is transmitted according to natural optical laws. The heat is emitted from any warm material to the cooler environment. In the process, the air is permeated with almost no loss and without heating it up.

This is precisely the effect used in infrared heaters and emitters in order to heat rooms. Solid objects, such as walls, furniture, people etc., absorb the thermal radiation and reflect it back into the room. Radiant heat is pleasant and physiologically beneficial. It gives a feeling of heat and creates cosiness - similar to sun rays or an open fire.

Heat conduction

Heat conduction transfers heat by means of direct contact, such as on a hotplate, for example. This type of heat transmission is not used for room heating.

Heat convection

Up until now, this heat transfer principle has been employed in almost all typical heating systems, such as central heating, oven heating, electric storage heating or convector heaters, rapid heaters and fan heaters.

How does infrared heating work?

Infrared heating is based on the principle of solar radiation. Rather than heating mostly air, the thermal radiation is absorbed to a far greater degree by the ceiling, walls, objects and people. The environment saves the heat and releases it back into the room (secondary radiation). Uniform room heating creates a pleasant room climate in which heating loss due to rising warm air is largely avoided.

In addition, direct thermal radiation, combined with the increased room envelope temperature (wall temperature), results in a subjective feeling of heat, 2-3°C above the actual temperature. This means that the perceived temperature is higher than the actual temperature. We encounter the same phenomenon on a cold winter’s day: due to direct sunlight, our subjective feeling of warmth is greater than the air's actual temperature.

As a general rule: the higher the wall temperature, the lower the room air temperature required for the same level of comfort.

According to the Bedford comfort scale, we feel the same levels of comfort when walls are heated, in spite of a lower room air temperature. Hence, the room air temperature can be reduced, and each degree less gives an energy saving of 6%.

A positive side-effect of this is that infrared heating reduces moisture levels in the wall, thus increasing the insulation value of many wall structures, preventing condensation and - in the worst case scenario - mould.

What differentiates infrared heating from other heating systems?

A correctly-dimensioned electrical infrared heater surpasses most other heating systems in terms of cosiness and comfort. It is clean, odourless and, what's more, it's maintenance-free. Thermal radiation can be used to maintain a suitable, uniform temperature in living areas. Heat can also be delivered to “comfort zones” in a targeted manner through precise placement of IR panels. As a result, the energy supplied can be pinpointed and used very efficiently, exactly where it is needed.

Conventional convection heating systems, on the other hand, use air to transport heat. The disadvantages of this are well-known: Rising warm air results in a large drop in temperature between floor and ceiling. While lots of energy is saved in the warm layer of air beneath the ceiling, which is not accessible to the user, the cooler air is located close to the floor. The user is forced to turn the room thermostat up further in a bid to stave off cold feet. In addition, the warm air flow swirls dust and bacteria into the room, creating an additional burden for allergy sufferers.

Infrared heaters, in contrast, do not cause swirling dust and bacteria - hence, they are ideally suited to allergy sufferers and asthmatics. Moisture is released from walls into the air due to the elevated wall temperature, improving insulation and room climate. Uniform temperature distribution in rooms enhances comfort.

When the overall costs for investment, operation and maintenance are calculated over 15 years, it is clear that it is difficult to find a more cost-effective heating system.

What are the benefits of IR heating systems?

Cosy heat - a pleasant indoor climate - no dry heater air
Precise temperature regulation by means of modern, single-room control
Greater flexibility due to short warm-up times in comparison to central heating
Easy to combine with existing main heating systems - also ideal for supplementary heating in rooms used only occasionally (bathrooms, guest rooms, recreation rooms, holiday homes, etc.)
Anti-allergic heating - prevents mould formation
The energy used is converted into 100% heat, directly in the room ¬– no heat loss due to transfer loss, buffer storage or piping.
Long lifetime with no maintenance costs (no corrosion or wear and tear)
Quick and easy to install
Low investment costs: In comparison to many other heating systems, investment costs for complete infrared solutions are considerably lower.
Low operating costs: By increasing the wall surface temperature and direct radiant heat, air temperature can be reduced by 2-3°C while maintaining the same feeling of heat. This effect is enhanced by increasingly effective heat insulation. Lower power requirements also speak for themselves: a 30m² room in a new build (passive-house standard) can be heated with 900W. Users can produce the required electricity themselves using photovoltaic systems.

What are the extra costs associated with infrared heating systems?

Neither maintenance nor other extra costs are incurred.

How is a heating system's performance discerned?

A heating system's performance is not discerned from its power input; rather, it can be discerned, in particular, by the ratio of energy used to radiation emitted. This means that the largest possible surface should be heated to the target temperature with the lower possible electrical power.

When assessing IR panels, we should never compare power ratings alone; rather we should always compare the size of heating surfaces. When we consider the physical fundamentals (Boltzmann's radiation law), we see that two panels of the same size, with the same surface temperature and the same material inevitably also emit the same radiation power. Hence, in this case: the lower the power rating, the higher the radiation ratio of the energy used.

What is the difference between infrared radiant heaters and infrared heating?

At core temperatures of some 100°C, IR radiant heaters emit mainly infrared-A and B radiation. Due to the high temperature, visible light is emitted in addition to the infrared radiation - hence, the emitters glow red or orange. Due to high power ratings and their intensive radiation cones with ranges of several metres, these elements are used for outdoor areas and for hall heating in particular

IR heating panels are so-called “dark radiators”; they emit infrared-C radiation and do not radiate visible light. Infrared-C radiation is used exclusively in room heating technology due to its minimal power requirements and consumption values as well as the optimal ratio between electrical energy used and heat output emitted.

See also: What is infrared radiation?

What is “heat load”?

Heat load - the heat supply required to maintain a certain room temperature - is standardised according to DIN EN 12831 and should be carried out by planners. Each room or area is considered on an individual basis in this process. The lowest expected outside temperature is also important for the purposes of calculation. The aim of the calculation is to ensure sufficient heating for all rooms of a building at defined external temperatures. Hence, heat load largely depends on: building structure, air change, external temperature, indoor room temperatures. It is expressed in watts (W) or kilowatts (KW). In order to be able to compare different values to each other more effectively, the rate of performance is relates to the heated surface; the relevant unit, then, is W/m².

What is meant by “heating demand”?

Heating demand is the calculated amount of energy to be supplied for the usable building area within the heating period in order to maintain the desired internal temperature. The unit of energy demand is defined in kilowatt-hours (kWh). It relates to the surface (m²), totalled for a period of one year (a): kWh/m²a. Heating demand is largely dependent on: the building envelope's “quality” (construction, insulation, etc.), user behaviour (presence in the building, room temperatures, etc.), hot water consumption, and weather. In general, heating demand is a parameter in construction and serves to define energy standards for housing.

How does IR heating fare in terms of consumption?

Consumption of IR heating depends to a large extent on the building envelope and on the heating’s application. If the IR heater is used as the main heating system, consumption is within a range comparable to a modern gas-fired condensing boiler. Although kWh of electricity cost considerably more than kWh of gas, there are numerous savings to be made with IR heating systems

See also: How are energy savings achieved?

How are energy savings achieved?

In contrast to convective systems, infrared heating panels produce almost no rising warm air, thus preventing heat loss to the ceiling. While the temperature difference between the floor and ceiling can amount to up to 8°C in rooms with convective heating, this figure is under 2°C as a rule in the case of infrared heating systems.
During ventilation, fresh cool air is warmed up again by the heat saved in the room envelope and in solid objects, quickly and with low energy expenditure.
By increasing the wall surface temperature and direct radiant heat, the air temperature can be reduced by 2-3°C while maintaining the same feeling of heat.
Radiant heat can be used to set up targeted heat “comfort zones” in rooms (e.g. desk, reading corner, conservatory, etc.) while, in the case of convective systems, the entire room volume must always be heated in full.

Taken as a whole, these factors result in a potential saving of up to 30% in comparison to similar systems when used as main heating systems. Where spot heating solutions are used in place of fan heaters, the potential for savings can even be significantly higher. It is significant that the comfortable temperature is 2 to 3 degrees lower in high-quality infrared heating systems than it is with ordinary heating systems due to the direct radiant heat and increased wall surface temperatures (with less heat dissipation from the object as a result). Even a reduction in temperature reduction of just 1 degree Celsius reduces heating costs by approx. 6%.

Can IR be used to heat an entire house?

Yes. IR heating is a fully-fledged heating system, best suited to heating entire objects. Correct individual dimensioning is an important factor in this regard. Indeed, high-quality infrared heating systems can be recommended highly as main heating systems for primary residences, as they demonstrate high levels of comfort and minimal acquisition and overall costs. Installation is easy, quick and clean.

Does the house/apartment have to be well-insulated?

IR heating systems are suitable for both new builds and (un)renovated old buildings. Correct, professional dimensioning is an important factor, and all relevant factors must be taken into consideration (such as insulation, for example). An energetically-sound building envelope makes a significant contribution towards keeping heating loss at low levels and heating efficiently.

How and where are panels fitted?

The panels are suitable for both wall and ceiling mounting. Use of mobile floor-mounted appliances is also practical. It is important that the heat waves are free to spread through the room and that they are not obscured or obstructed by furniture or other fixtures.

Does the wall the IR heating is mounted to heat up?

The wall behind the IR heater is naturally warmed slightly because the heat element emits low levels of heat waves backwards. Due to uniform distribution of heat waves in the room and the distance required between the panel and the wall, however, the wall does not become hot; rather, when the room is fully heated, its temperature is roughly the same as the rest of the walls.

How is an IR heating panel controlled? How is the temperature regulated?

IR heating panels can be regulated using a radio thermostat, plug-in thermostat (quick and simple installation) or with a securely-connected thermostat.

Can IR heating be used to prevent mould?

Mould formation is prevented because IR heating results in wall temperatures that exceed the room temperature.