How Do Halogen Heaters Work

Many people ask how do halogen heaters work. In this article, we will answer this question.

Halogen heaters are a great way to bring warmth and comfort into your home. Halogen heaters work with the use of a kind of incandescent light bulb. These bulbs generate infrared radiation, which we feel as heat. The heat energy is directed outwards from the heater in a beam of warmth. They provide fast and efficient heating at an affordable price.

This is a basic outline of how halogen heaters work. If you wish to have a more in-depth understanding, then read on.

How Do Halogen Heater Work – the essential components

Halogen heaters are simple appliances with only a few essential components. The most important part is the halogen bulbs. These bulbs are the component that generates the heat.

Behind the halogen bulbs is a mirrored reflector. As the halogen bulbs emit radiation in all directions, the reflector is a vital component. The reflector directs radiation emitted backward forward.

Halogen heaters have switches and knobs to control how much heat is generated, control any swinging action and turn the appliance off and on. These controls connect to the bulbs and the mains supply.

The halogen bulbs, reflector, controls and wiring, are contained in a housing. The housing includes a front grill that allows the emission of radiation. It also prevents direct contact with the halogen bulbs.

What is a Halogen Bulb?

how do halogen heaters work - EM spectrum

A halogen bulb is an advanced incandescent light bulb optimised to emit infrared radiation.

Infrared radiation is a band of electromagnetic waves (shown in the image to the left). Infrared radiation frequencies are between visible light and radio waves (Infrared), and such is not visible. While most of the radiation from the bulb is within the infrared range, they also emit radiation within the visible light spectrum. This is why they emit some visible light. I have glossed over what is quite a complex subject. If you wish to understand more about the electromagnetic spectrum please check out the article on Wikipedia.

You may be interested in how to replace a halogen bulb.

Internal Structure of Halogen Bulbs

Halogen bulbs comprise a glass tube containing a coiled tungsten filament. The space between the gas and filament contains a mixture of inert gases under high pressure. A small amount of halogen gas is added to prolong the filament’s life.

Halogen bulbs on a table — A collection of halogen heater bulbs

Halogen gas is not a single gas. For our purposes, the halogen gases are fluorine, chlorine and bromine. As chlorine is corrosive, fluorine and bromine are used in halogen heater bulbs. The role of the halogen gas is to prolong the filament’s life. We will look at this in more depth shortly.

The halogen bulbs in heaters operate at high temperatures. As the encasing body needs to withstand these temperatures, halogen bulbs use quartz glass.

Some halogen tubes incorporate a reflective coating to direct heat forward.

Halogen Bulbs in operation

When you turn on a halogen heater, electricity passes to the bulbs. The tungsten filament quickly reaches its operating temperature and provides almost instantaneous heat. At operating temperatures, the bulbs reach as high as 1000^oC (3250^oF). At these temperatures, some of the tungsten vapourises. The role of the halogen gas is to ensure that the evaporated tungsten is redeposited on the filament. As the tungsten evaporates it combines chemically with the halogen gas. The tungsten is later redeposited on the filament. If the gas were not present, some of the tungsten would be deposited on the glass, limiting the bulb’s life.

Of importance is that halogen gas is not involved in heat production. Its only purpose is the extend the life of the bulb. The component that produces the radiation is the filament.

Emission of heat

With the filament at operating temperature, it emits radiation. The frequency of the radiation is in proportion to its surface temperature. At the operating temperature, the bulbs mainly produce infrared radiation. If you are looking for technical details of the radiation emitted, look at Black-body radiation.

From the filament, the radiation travels through the gasses in the tube and the quart glass encasement. It does so as they are transparent to the radiation. The air surrounding the heater is also transparent to the radiation, so it travels through it without heating it significantly.

Eventually, the light encounters a surface. This surface may be your skin. Within your skin, the radiation is converted to heat due to the interaction of the radiation and atoms in your skin. Similarly, other surfaces are also heated, which heats the room air.

I want to point out that we receive heat from the Sun similarly. The Sun’s surface is analogous to the filament. It produces more light in the visible range. However, it also produces a lot of infrared radiation. This is why we feel warm when standing in sunlight.

Distribution on heat

Not all surfaces are heated equally. Light-coloured surfaces may reflect some of the radiation. However, more importantly, distance has a significant effect on heating efficiency.

Radiation suffers what is known as the inverse-square law (https://en.wikipedia.org/wiki/Inverse-square_law). As the radiation propagates, it becomes more spread out. If we double the distance from the heater, we feel only a quarter of the same heating effect. This means that the heat felt drops off quickly as we move away from the heater.

An important implication of the inverse-square law is that objects very close to the heater receive a higher concentration of radiation. This is why halogen heaters must not be directed towards flammable objects at close range.

Conclusion

Halogen heaters are a great way to generate targeted heat. By understanding the different parts of a halogen heater, you can decide which type of heater is right for your needs.

The most critical component of a halogen heater is the bulbs, which emit radiation and produce heat. The reflector directs the radiation forward to where heat is required, and the controls allow you to regulate how much heat the bulbs generate. When making a purchase, consider all of these factors to choose the best halogen heater for your needs.

To summarise: