The Science Behind the Infrared Heat Lamp: From a Basic Lamp to Complex, Ever-evolving Technology

Introduction: What is an Infrared Heat Lamp?

The Infrared Heat Lamp is specifically designed to heat up nearby food items by emitting infrared radiation at a lower wavelength than the visible light emitted by conventional light bulbs. This allows it to heat food typically below 135 degree Fahrenheit in the oven. It is not capable of emitting heat at a distance as heat lamps and space heaters do. It is not designed to warm air in the room.
The Infrared Heat Lamp is designed to be used in food warming applications where there are food items that are being sold to customers who eat while they shop, and need their food items warmed up. Restaurants and convenience stores commonly employ infrared heat lamps for this purpose, as such environments require fast turnaround time for each customer.
Outside of these food warming applications, infrared heat lamps can be used to warm up the air in a central heating system, as well as other applications where it is desired for the air to reach about room temperature. This allows for more comfortable and private sleeping environments.

heat lamps are designed to reheat food when it falls below 135
heat lamps are designed to reheat food when it falls below 135

What does a heat lamp do?

A heat lamp will heat food by emitting infrared, at a lower wavelength than visible light. It does this by heating a metal plate called a radiator which emits infrared radiation at the same frequency as visible light but with wavelengths shorter than the visible spectrum. The radiation is then directed onto the surface of food that has been placed in close proximity to the radiator. The food absorbs this heat, and is then warmed up.
As infrared radiation can pass through cardboard boxes and plastic bags, it is not effective for heating food inside these containers. Another disadvantage of heat lamps is that the radiant heat does not travel far from the lamp itself. If food is placed too close to the lamp, then it will not be heated fully, and may not cook properly. This means that if an item of food is placed under a lamp, then it will only be heated partially and may become overcooked.
Heat lamps are designed to reheat food when it falls below 135 °F according to the US Department of Agriculture.
All heat lamps have an external radiator, which heats food that happens to be placed in close proximity with the lamp. A heat lamp’s operating temperature is around 350 degrees Fahrenheit. The temperature of the food being heated by a heat lamp will be low enough for it to not burn but high enough for it to retain some energy—a constant rate between 45 and 50 percent.
The energy required to heat* a specific volume of food is given by .
A heat lamp will have an average efficiency of 25% in heating the food it sits on, and 80% in heating the air that it sits in. So, if 10 units of food are placed under a heat lamp, and 5 units are placed within a radius of 1 foot from it, then the efficiency will be:

heat lamps are designed to reheat food when it falls below 135
heat lamps are designed to reheat food when it falls below 135

How does the spectral power distribution of an infrared heater affect the performance of indoor lighting?

When an infrared heater is used in conjunction with incandescent, fluorescent and/or high-intensity discharge lamps, it produces a combination of visible, infrared and ultraviolet radiations. The proportion of visible radiation depends on the composition of each lamp; this is determined by their chromaticity coordinates. Conventional incandescent lamps have low levels of infrared radiation but are typically used in conjunction with infrared heaters. Consequently, the visible radiation provided by these lamps is greater than the infrared radiation produced by the heater. This results in a reduction of the overall power density (W/m2) on surfaces near to the heater’s radiator thus reducing its effectiveness in heating.
Infrared heaters should be used in conjunction with lamps that have a high proportion of their radiations in the visible range, such as compact fluorescent lamps (CFLs) and high intensity discharge lamps (HID). When performing calculations, it is necessary to determine which lamps will be used with the heater.
The spectral power distribution of each lamp has an effect on the resulting heating pattern. A number of research papers have considered this effect; however, little information is available in the literature regarding how spectral power distributions affect lighting systems.

heat lamps are designed to reheat food when it falls below 135
heat lamps are designed to reheat food when it falls below 135

How do heat lamps work and what is their function?

Infrared heaters work differently to other types of lamp. They rely on heat radiation, and as such do not naturally emit light, unlike fluorescent lamps and incandescent lights. The infrared heater radiator is an engineered piece of metal which absorbs the infrared radiation from whatever source is used to heat the filament (in a fluorescent light) or the gas in a gas burner to create energy. This energy heats up the radiator which then heats up food placed within its proximity. This is why a heater must be used with some types of lamp. A deficiency in the infrared wavelengths emitted by incandescent light bulbs or fluorescent tubes will reduce the effectiveness of an infrared heater as it will not produce enough light to heat food efficiently.
A heat lamp is usually placed over a table to keep the food warm; however, it may also be used for cooking. Because of the radiant heat, which does not heat food from within, but rather from above, heat lamps also need to be used when roasting meat.
There are two types of infrared heating elements: Infrared Quartz and Infrared Ceramic. Because Infrared Quartz elements are more energy efficient than Ceramic ones they are used almost universally in infrared heating systems.

heat lamps are designed to reheat food when it falls below 135
heat lamps are designed to reheat food when it falls below 135

Conclusion and Final Thoughts on Heat Lamps

Infrared heaters have their advantages and disadvantages. When used in conjunction with incandescent or fluorescent lamps, they are more efficient at heating food than heat lamps as a whole although this will depend on the type of material being heated. It is important to remember that infrared wavelengths are not visible to the naked eye and so cannot be seen by the naked eye, but they can be detected by thermal imaging cameras. Due to their efficiency, they are also environmentally friendly as they do not generate light as incandescent lamps or fluorescent tubes. Quality infrared heaters, in conjunction with incandescent or fluorescent lamps, will effectively produce infrared and visible light to thoroughly cook food that is placed within their proximity. However, if the quality of the infrared heater falls below a certain standard then the efficiency of the lamp will also be reduced.

heat lamps are designed to reheat food when it falls below 135
heat lamps are designed to reheat food when it falls below 135