Infrared heating works through thermal radiation, similar to the way the sun emits infrared rays. When these rays reach a surface, they are absorbed and converted into heat. Understanding this principle helps you choose the right infrared Outdoor Heater for each space to improve comfort and energy efficiency.
Understanding the Differences Between Short-Wave, Mid-Wave and Long-Wave
Mid-Wave (IR-B) and Long-Wave (IR-C) are ideal for comfort heating because they offer high absorption and low reflection. They do not penetrate deeply into the skin, providing a softer more natural warmth. Whereas Short-Wave infrared heaters operate at extremely high temperatures, generating an intense heat that can be felt even at a distance. However, much of the radiation is reflected and not absorbed by the human body. This makes Short-Wave heaters less efficient for comfort heating.
Short-Wave Infrared Heaters
Short-Wave infrared, sometimes called near infrared, typically falls between about 0.7 and 1.4 micrometres. These heaters operate at high element temperatures, often above 1,800°C in electric quartz systems and high-intensity gas radiant systems.
Key Characteristics
- Produces a bright visible glow.
- Delivers high-intensity radiant energy.
- Penetrates further before being absorbed.
- Provides very rapid heat response.
Because of their high surface temperature, Short-Wave heaters emit a large amount of radiant energy in a concentrated form. The radiation is absorbed quickly by skin and clothing, resulting in an immediate warming sensation. This makes them particularly suitable for the following applications:
- Open outdoor areas.
- High ceilings.
- Wind-exposed spaces.
- Spot heating in commercial settings.
In windy outdoor environments, Short-Wave infrared performs well because the heating effect does not depend on air temperature. Even if wind cools exposed surfaces, the heater continues delivering radiation directly to occupants. However, the visible brightness may not be suitable for all architectural settings. In hospitality venues, aesthetics can influence the choice between Short-Wave, Mid-Wave and Long-Wave technologies.
Mid-Wave Infrared Heaters
Mid-Wave infrared typically spans from about 1.4 to 3 micrometres. Element temperatures are lower than Short-Wave systems, generally between 800°C and 1,500°C.
Key Characteristics
- Reduced visible light output compared with short wave.
- Moderate penetration depth.
- Slightly slower warm-up time.
- Balanced radiant intensity.
Mid-Wave heaters are often used in semi-enclosed outdoor areas, such as covered patios, balconies and alfresco spaces. They provide effective radiant warmth without the intense brightness associated with high-temperature Short-Wave elements. The sensation of heat from Mid-Wave systems is often described as softer. This is related to the way energy is absorbed at the surface of the skin and clothing. The overall heating mechanism remains radiative, not convective.
Long-Wave Infrared Heaters
Long-Wave infrared, often called far infrared, typically ranges from about 3 micrometres up to 1 millimetre. In practical heating systems, the relevant range is usually between 3 and 15 micrometres. Surface temperatures of Long-Wave heaters are much lower, often between 100°C and 500°C.
Key Characteristics
- No visible glow.
- Gentle radiant output.
- Surface-level absorption.
- Slower initial heat perception compared with short wave.
Long-Wave infrared is strongly absorbed by most materials at the surface level. It does not penetrate as deeply as shorter wavelengths. Indoors, this can be advantageous because walls, floors, and furnishings absorb and then re-radiate heat, contributing to stable thermal comfort.
Outdoors, the lower intensity and shorter effective range mean Long-Wave heaters are best suited to:
- Enclosed or sheltered spaces.
- Low air movement conditions.
- Areas where visual impact must be minimal.
In fully exposed environments with significant wind, Long-Wave systems can struggle to deliver the same perceived warmth as Short-Wave systems. The physics of radiant transfer remains valid, but heat losses increase in exposed outdoor conditions.