This article will take an in-depth look at radiant heaters.
The article will bring more detail on topics such as:
This section delves into the fundamental principles guiding radiant heaters, exploring their operational mechanisms and distinctive design features.
Radiant heaters are heat-generating devices that transmit warmth to nearby objects and individuals, much like the sun's effect. When exposed to sunlight, the warmth sensed on our skin is due to the sun's emitted infrared radiation.
Infrared heating employs electromagnetic waves to convey energy directly to the target object, effectively bypassing the surrounding air. This method produces energy within the 0.7 to 6 microns (µ) range. By selecting specific wavelengths tailored to the target, infrared heating minimizes energy consumption, enhancing efficiency.
In contrast to traditional heaters that warm the surrounding air, radiant heaters transfer heat directly to people and objects nearby, thereby avoiding the dry air typically associated with convection heaters.
Radiant heaters generate heat internally and convey it through electromagnetic waves, which convert into heat upon striking an object or individual. These waves traverse the air with minimal energy loss, heating surfaces such as floors, walls, or people they contact. Similar to how clothing absorbs sunlight, objects in a space capture this radiant energy to provide warmth.
Radiant heaters can deliver warmth without requiring direct interaction with the heat source, much like feeling the sun's warmth without physical contact. This is particularly advantageous in industrial environments where direct heat source contact is undesirable. Unlike conduction and convection, which transfer heat via molecular movement, radiant heaters utilize electromagnetic waves.
Radiant heaters transmit heat energy through electromagnetic waves, eliminating the necessity for any heat transfer medium. The emitted heat from a surface increases substantially with temperature escalation. Doubling the temperature can result in up to 16 times the heat emission. When in the radiant heat field, warmth is directly experienced from the source.
Even in colder air, absorbed radiant heat provides comforting warmth. This infrared radiation principle is effectively harnessed in commercial offerings such as tube space heaters. These radiant heaters function as decentralized systems, converting energy into heat with low losses, unlike traditional central heating systems.
The primary components of radiant heaters include:
At the heart of a radiant heating system lies a core resembling a boiler. Utilizing heated water as the main heat source, it features a tank where gas is expelled, or electric elements heat the water, followed by a pump circulating the water through a closed system.
Positioned within floorboards, these pipes carry heated water from the tank, raising the floor's temperature and acting as an effective heat source. Typically using PEX tubing, these pipes can be installed within or on top of a subfloor, or beneath it.
Installed between the in-floor pipes and the water tank, this component regulates water distribution. The manifold's complexity varies based on how many areas have in-floor piping.
Several factors should be considered when designing an effective radiant heating system:
Radiant heaters use the floor itself to warm spaces by balancing the building's heat loss with the floor's heat output. Determining necessary floor temperature involves assessing the building’s heat loss, then selecting a radiant system, tube spacing, and fluid temperature for efficiency.
Calculate the heat loss per square foot, given temperature differences. For instance, with an indoor temperature of 65 degrees Fahrenheit and an outdoor temperature of -10 degrees Fahrenheit, the heat loss is 22.5 BTUs/hr per square foot (based on temperature difference x heat loss rate).
An 80-degree Fahrenheit floor temperature can provide 27 BTUs/hr, sufficient for well-insulated systems in sub-zero conditions. For heat source sizing, multiply the heat loss per square foot by total area to determine heater or boiler output requirements.
Estimate potential heat output from the floor, considering outputs above 45 BTUs/hr typically require over 90-degree floor temperatures. If outputs need to be higher, consider additional heating sources and energy conservation measures, including ceiling or wall heaters for supplemental comfort.
Uncertainty about whether the radiant floor will be sufficient prompts consideration of:
Functional maximum floor temperature should not exceed 80 degrees Fahrenheit, with an absolute cap at 85 degrees Fahrenheit.
Ensure proper tube spacing aligns with desired fluid temperatures for uniform heating spread, usually 8-12 inches for 1/2-inch diameter tubes.
To calculate the requisite tubing length, multiply the floor area by a spacing-specific multiplier—e.g., 0.75 for 16-inch spacing.
Avoid excessively short or long circuits. Proper tubing facilitates effective heat exchange; overly long tubing risks premature heat dissipation and heating inefficiency, potentially mitigated by increasing fluid velocity. Conversely, extremely short circuits may hinder heat exchange and air purge efficiency. Ideally, fluid exits should maintain a 10-15 degrees temperature difference from entry, allowing mild turbulence for effective transfer.
Radiant heaters are an efficient heating technology used in residential, commercial, and industrial applications to deliver comfortable warmth. Homeowners, builders, and facility managers choose radiant heating systems for their ability to provide consistent, energy-efficient heat, reduce utility costs, and minimize the allergens and dust often associated with forced-air heating. Below, we explore the major types of radiant heaters available, their installation methods, best uses, and key benefits, to guide your decision-making process when evaluating radiant heating solutions.
This type of radiant heating system makes use of electric coils that are capable of producing heat as electricity passes through them. These metal coils are able to resist electricity. When electricity passes through the coil, the resistance emanates heat. Polymer sheets are wrapped around these coils so that they can act as insulation. They can heat the wall of the ceiling or floor, as mentioned earlier, depending on their location.
This method is commonly used for radiant floor heating and is known for its low maintenance needs and long lifespan compared to other systems. Electric radiant heaters can be floor-mounted, wall-mounted, or even integrated into ceiling panels, making them flexible for space heating needs in both new construction and retrofit projects. However, operating these systems can be costly due to rising electricity prices.
They tend to be more energy-efficient in smaller areas such as driveways or bathrooms. For spot heating or as a supplemental heat source, electric radiant floor heating is a popular choice for modern bathrooms, kitchens, and under-tile installations, delivering quick, on-demand warmth where it’s needed most.
Primary Advantages: Fast installation, zoned heating control, improved indoor air quality, and compatibility with various flooring types make electric radiant heating systems a top alternative to traditional HVAC and baseboard heaters.
These radiant heating systems utilize a boiler to circulate heated water through a network of pipes installed throughout the house or floor. They can also be fitted in ceilings and walls. Hydronic radiant floor systems feature PEX tubing, reliable thermostatic controls, and energy-saving circulator pumps. Although their operational costs are generally lower than those of electric heating systems, there is a risk of pipes bursting or leaking.
Hydronic radiant heating systems are the most energy-efficient and cost-effective option for heating an entire house, offering low operating costs, impressive thermal comfort, and the flexibility to use natural gas, propane, or solar-assisted water heaters as an energy source. This makes them highly popular for green building projects, radiant snow melting, and whole-home heating upgrades.
Common Applications: New home construction, retrofits, large open spaces, and radiant snow melting systems for driveways and walkways.
These radiant heating systems use heated air to transfer warmth. Out of the three standard heating methods, they are the least efficient due to air's limited ability to carry and retain heat. This inefficiency is exacerbated in older homes, which may have more air leaks or cracks that allow heat to escape. Air radiant heating is rarely used as a primary heat source in residential settings but is sometimes applied in specific commercial or solar thermal systems.
While not ideal for most home heating needs, air radiant heaters may offer certain advantages for workshop spaces, solar air heating collectors, or as part of hybrid HVAC systems where air is readily available.
Examples of radiant heating systems include:
These radiant heating systems utilize infrared radiation to directly warm objects and people in a space. This approach is more comfortable and efficient compared to air-based heating systems, as it provides consistent warmth from the ground up, minimizing cold spots and drafts. Radiant floor heat is often appreciated for its silent operation, even temperature distribution, and the luxury feel it adds to living spaces.
The principle of radiant floor heating involves radiating thermal energy from the floor surface, similar to how heat from a stove burner can be felt from a distance. This system does not warm the air directly but instead makes people and objects in the room feel warmer. This method supports both energy efficiency and increased indoor comfort, as heat loss through ventilation is minimized compared to forced-air furnaces.
Radiant floor heating systems are categorized into two types: wet and dry installations. It is important to note that this classification does not refer to the heat transfer medium itself; the terms "dry" and "wet" do not relate to electrical resistance or hydronic piping.
This is the oldest type of radiant floor heating installation. It tends to be more costly compared to dry installations because it involves embedding mats, electrical cables, or hydronic tubing within a concrete slab, whether thick or thin. Although it takes longer for the system to heat the floor and room air, the substantial thermal mass of the concrete retains heat for several hours after the system is turned off.
Wet installations are highly compatible with hydronic systems in new construction, basement slab applications, and radiant snow melting systems for driveways and patios.
This type of radiant floor heating is easier to set up, less costly, and more convenient. Mats, heating cables, or tubing are installed in an air pocket beneath the floor rather than being embedded in concrete. As a result, heating is achieved more quickly compared to wet installations. However, this setup requires operating at higher temperatures since it is not integrated into the flooring material.
Dry installations are ideal for retrofit projects or where minimal floor height changes are desired. Many homeowners choose dry-installed electric radiant mats for kitchen and bathroom renovations, since they provide fast, controllable warmth with minimal disruption to existing floors.
The types of radiant floor heating systems are:
These are the earliest types of radiant heaters. Air heaters are somewhat less efficient compared to other types and are thus less common. Instead of directly pumping air beneath the floor, heated air is circulated through a network of tubes, similar to how water is distributed.
The key difference is that air is lightweight and can be moved more easily through the tubes, which can make the system faster. In this setup, a heater pushes air through tubes or ducts installed in the floor rather than through vents. Although this system can be challenging to make energy-efficient, it generally requires less space because the heaters and ducts are embedded in the floor, eliminating the need for a large furnace or boiler.
It is crucial to ensure that the system is properly sealed and installed, typically using a wet installation method. Heaters can be placed in accessible locations and are housed in boxes within the concrete, making repairs and maintenance simpler if needed. Air-heated floor systems can be used in various building types and with different floor materials such as engineered hardwood, hardwood, tile, laminate, stone, linoleum, vinyl, and concrete.
Their installation can be made either in a suspended floor system or in a structural slab on grade. When the installation is done in a slab, the ground is covered with a layer of polystyrene installation after leveling the ground. This is then used in the holding of the furnace piping, boxes, and ductwork, which are held in place by means of a level of mesh.
Concrete is then poured over the installation as usual to create the slab. Curing begins after three days, with the entire process taking approximately three weeks. While retrofitting is possible, it still requires poured concrete and wet installation; dry installations may not be feasible with this system.
Note: Due to advances in hydronic and electric systems, air radiant floor heat is now quite rare for residential heating installations.
In electric radiant floor heating systems, cables or wires—and sometimes mats in smaller areas—are installed beneath the flooring using either dry or wet methods. These wires connect directly to the home's electrical system, and a thermostat is used to control the floor's temperature.
The system comprises several key components: heating elements (wires or mats), in-floor sensors, and a thermostat. For smaller spaces, mats with embedded wires are placed in a thin layer of mortar, cut to fit the specific area. In larger areas, wires are typically spaced about 3 inches apart and also embedded in a thin mortar layer.
A type of heat-conducting plastic is used to transfer heat from the cables to the floor above. Electric radiant floor heating systems heat up more quickly since the cables produce warmth immediately, unlike systems that require water or air to be heated first before being circulated. These systems can be installed under any flooring type without raising the floor level significantly due to their thin cables.
While both the installation and operation of electric radiant heaters are more expensive, they offer faster installation and less disruption, particularly in small areas like bathrooms. They are often used as a supplementary heat source, providing a reliable solution for specific cold spots in residential or commercial buildings. Some models are compatible with smart home thermostats, allowing homeowners to optimize energy usage and monitor system performance.
Hydronic radiant floor heating systems utilize hot water to heat a building and are the most efficient among the three types. These systems feature a hot water heater or boiler that heats the water, which then circulates through a network of PEX tubes installed beneath the floor using either dry or wet methods. The hot water moving through these tubes warms the floor above. The system operates in a closed loop, allowing water to circulate continuously. This type of radiant heating can be installed beneath any flooring type and is highly efficient, consuming up to 30% less energy compared to traditional forced-air furnaces, which can significantly reduce energy bills. It also offers various installation options, making it suitable for retrofitting.
Hydronic systems are ideal for heating large areas, multi-residence buildings, commercial spaces, and energy-conscious projects looking to minimize carbon footprint and maximize indoor air quality. With modern controls and zoning, homeowners can tailor temperatures for each room, improving efficiency and personalized comfort even further.
The performance of radiant floor heating is greatly affected by the choice of flooring material. Thermally conductive materials can improve efficiency, while insulating materials can hinder it. This does not mean insulation should be avoided entirely, but it should not be placed where it can obstruct heat transfer between the radiant system and the indoor environment. Ceramic tile is one of the most effective materials due to its thermal conductivity and high heat storage capacity. In contrast, materials like vinyl and linoleum offer excessive insulation, reducing system efficiency. Wood floors can conduct heat well, but laminated wood is preferred over solid wood, which can dry out and contract more easily.
Tip: Always consult with a radiant heating professional to determine the most compatible flooring option for your selected radiant heating system.
Radiant heating systems are not limited to floors; they can also be installed in walls and ceilings. Floor-based radiant heating is often the most effective because it ensures even heat distribution throughout the space.
Radiant panels can be mounted on walls to heat smaller rooms, but they are generally less effective than floor or ceiling installations due to difficulty in covering large areas. On the other hand, radiant ceiling heating systems can be more efficient than floor systems since they only heat the air, not the floor itself. This method can provide a very comfortable environment without disrupting existing flooring. For specialized applications, such as spas, yoga studios, and healthcare facilities, radiant wall or ceiling panels may offer targeted comfort and easy retrofitting.
These radiant heaters are a recent addition to the market and provide several benefits. One major advantage is their slim profile, which does not occupy floor space. They offer a more even distribution of heat from head to toe. In terms of safety, these heaters are also a better choice for homes with small children and pets.
Wall-mounted radiant panels are often used for supplemental heating in bedrooms, offices, and hallways. The installation process is typically straightforward, and many models offer smart controls for energy management and scheduling. Their sleek, modern design complements contemporary interiors while promoting energy-efficient, on-demand spot heating.
Popular Types: Electric infrared wall heaters, low-profile hydronic panels, convection-radiant wall units.
In this type of radiant heating system, the radiant heat panels are installed in the ceiling. These panels then radiate heat downward to warm objects and people below. When the radiant ceiling is heated just a few degrees above the surrounding surfaces, it promptly emits infrared heat in all directions.
These radiations directly warm any object or surface in the vicinity, whether they are above or below the panels. Radiant ceiling heaters are often used in offices, healthcare facilities, and retrofits where floor or wall installations are not feasible. Since heat is delivered precisely where needed, ceiling radiant panels can efficiently supplement existing HVAC systems and improve overall thermal comfort.
These radiant heaters are generally smaller than wall-mounted models and offer the advantage of easy mobility between rooms. This flexibility is particularly useful when heating needs to be directed to various locations. They are also well-suited for providing heat in very small spaces.
Freestanding radiant heaters, such as portable infrared heaters and oil-filled radiators, deliver targeted, rapid warmth and often feature safety cutoffs, timers, and variable power settings. These devices are practical for renters, workshops, garages, and seasonal room use where permanent installation is not practical.
In Summary: When choosing the best radiant heater for your space—whether it’s for new construction, retrofitting an older home, optimizing commercial energy efficiency, or adding supplemental warmth—understand the advantages, installation requirements, and design compatibility of each system. Electric, hydronic, and air radiant systems all have unique benefits, and matching your heating needs with the right technology ensures optimal comfort, efficiency, and value for years to come.
This chapter will explore the uses and advantages of radiant heaters.
Radiant floor heating systems provide several advantages. Since they don’t warm the air, the temperature in the room remains more consistent from the floor to the ceiling, eliminating cold spots on the ground. This leads to increased comfort and often reduces energy consumption, thereby lowering heating costs. They are compatible with a wide range of flooring types, preserving the aesthetic of a home. Additionally, because these systems do not rely on air ducts, they minimize the circulation of allergens. Operating radiant floor heating systems is straightforward and efficient.
Hydronic radiant floor heating systems offer even heat distribution throughout a building at a lower cost, making them ideal for larger businesses and facilities that own their premises. These systems provide comfort for both employees and customers, eliminating cold or hot spots in retail environments.
Electric radiant floor heating systems are highly adaptable, supporting both wet and dry installations and various retrofits. They are quick to install and can be used almost immediately, making them suitable for large buildings with multiple offices that need individual temperature control.
Free-standing radiant heaters are portable and can be easily relocated to different areas as needed.
Despite some drawbacks, the advantages of radiant heaters significantly outweigh their disadvantages.
Radiant heaters operate most effectively when placed close to the objects or people they need to warm. Whether the room is open or closed is less important, as the focus is on directly heating individuals or items rather than the surrounding air.
Since radiant heaters do not use blown air, they avoid creating drafts, which can be particularly beneficial for individuals with asthma, allergies, or other respiratory issues. They are well-suited for rooms that have specific functions, are smaller in size, or are infrequently used, such as bathrooms and bedrooms.
Radiant heaters are also a great energy-efficient option for spaces like garages, basements, storage sheds, workshops, and patios that require temperature regulation.
Radiant heaters are systems used to warm objects or people directly within space. They generate heat internally and do not require an air medium to transmit the heat. They do not warm the surrounding air but target the object or person. There are different types of radiant heaters available including air, electronic and water radiant heating systems. Each radiant heating system offers its own unique benefits. Therefore it is wise to consider the specifications of the type of radiant heater before selecting one. Some are more suitable in small areas whereas some are more suitable for large areas. Radiant heaters can be installed beneath the floor, on the walls or in the ceiling. There are also free standing radiant heaters offering the main benefit of being easily moved from one point to the other. Radiant heaters have a wide range of applications as mentioned before.
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