This article will take an in-depth look at radiant heaters.
The article will bring more detail on topics such as:
This chapter will discuss what radiant heaters are, how they work, and their construction.
Radiant heaters are systems that generate heat internally and then radiate it to the nearby objects and people. The sun is a basic example of a radiant heater. When we feel warm on our bodies on a sunny day, it is because of the infrared radiation (heat energy) generated by the sun.
Infrared heating uses electromagnetic waves to transfer energy from the infrared source to the product to be heated without heating the air between. Its energy is emitted between 0.7 and 6 microns (µ). At peak efficiency, wavelengths are selected for the product to be heated, minimizing energy usage.
A radiant heater does not heat the air of the surrounding environment like other types of heaters. It radiates heat to the people and physical objects within the space. Therefore, no dry air is experienced as convection heaters create.
When radiant heaters generate heat internally, it is transmitted through electromagnetic waves. The interception of these waves by any object or people causes them to be converted into heat. The radiant heat travels through the air nearly without loss and heats only when it hits the floor, walls, or body. The objects in a room absorb the radiant energy and warm the space the same way clothes absorb light from the sun.
Radiant heaters are capable of heating without direct contact with the heat source (for instance a person does not need to touch the sun to feel its warmth). This type of heat is beneficial for an industrial application, when trying to avoid physical contact with the object that is being heated, or want to prevent the contamination of the product being heated. While in conduction and convection, the thermal energy flows from the location of higher temperature to the lower one in the form of molecular motions.
With radiant heaters, the thermal energy flows in the form of electromagnetic waves, meaning to say there is no heat transfer medium. The heat energy emitted by a surface is disproportionate to the difference in temperature. This means that when the temperature of the heat source is doubled, there will be an increase in the emitted radiated heat to about 16 times. When a person is standing in the radiation exchange with the heat source perceives direct heating.
The radiant heat that is absorbed is felt quite comfortable despite air temperatures that are low. The efficient principle of infrared radiation is utilized commercially in tube space heaters and luminous heaters. Infrared radiant heaters are decentralized heating systems, whose energy is converted into heat without any loss of energy during transport contrary to central heating.
The main components of radiant heaters include:
A radiant heating system looks the same as a boiler, at its core. It makes use of heated water as its source of warmth. As with a boiler, it consists of a tank where either the ejection of gas occurs or electric heating elements raise the water temperature, and then a pump is used to circulate the water through the closed system.
These pipes set into the floorboards allow for water running from the tank. The temperature of the floor is raised by the heat from the pipes, and they become the heat source beneath the floor. These pipes that are used are usually made from PEX tubing and are either housed in a concrete slab, over a subfloor under a subfloor.
Usually, the installation of this component is done between the in-floor pipes and the water tank to help in the regulation of the distribution of the water. The complexity of the manifold is dependent on how many areas of a home have in-floor pipes.
The considerations in designing a radiant heating system include:
Radiant heaters under the floor make use of the floor in the heating of the above area raising the temperature of the floor until the heating output of the floor matches the quantity of heat being lost by the building. The heat loss of the building must be estimated in order to estimate the temperature of the floor that will be required to do the job. Then the radiant method to be used can be decided and what should be the tube spacing and the temperatures of the fluid in order for the execution of the job in a manner that is the most efficient.
This involves the determination of the heat loss per square foot of a building. For instance, the loss of heat per square foot of a building which is 65 degrees Fahrenheit inside and -10 degrees Fahrenheit outside = 22.5 BTUs/hr. /sq. ft. (temperature difference x heat loss) (30 BTUs/hr. /sq. ft. /degree Fahrenheit x 75 degrees Fahrenheit).
For example a floor temperature of 80 degrees Fahrenheit will be enough to put out 27BTUs/hr. This will be adequate in the heating of a system having good insulation when it is below zero. Almost every residential building and most commercial buildings are built up to a standard like this today. For the sizing of the heating source, simply multiply the heat loss/sq. ft. by the area in square feet. There will be a need for a heater or a boiler with such a rated output.
This involves the prediction of the amount of heat that is obtained from the floor. It’s impossible to achieve heating outputs that are greater than 45BTUs per hour without floor temperatures above 90 degrees Fahrenheit. In those rare cases where there is a requirement of more than 45BTUs per square foot, use supplementary heat, and invest in energy conservation measures. When there is use of radiant ceiling or wall heat as a supplement, they will provide exceptional comfort.
When there is no assurance that enough heat will be obtained from the radiant floor, do the following:
Floors must not go beyond 80 degrees Fahrenheit on a routine basis and must never go beyond 85 degrees Fahrenheit.
More comfortable even heat will be provided by the tube spacing, within the fluid temperature limits that are desirable. An example is a tube diameter of 1/2 inches corresponding to a spacing of 8-12 inches.
Determine total length that is required for tubing by multiplying the area of the floor in square feet by the multiplier specified for tube spacing. If the spacing of the tubing is going to be 16 inches, multiply the floor area by 0.75.
It is recommended that the lengths of the circuit must be neither too short nor too long. The purpose of tubing is for the allowance of water to pass through it and lose heat when it flows in the tubing. The floor receives this heat, and the heat then heats the building. If the length of the tube is too long, there will be a tendency of the water to lose more heat before the end of the run is reached. The result is that the tubing at the end of the circuit is exposed to water that has lost more of its heat already and the tubing is then loafing. This can be made up for by an increase in the velocity of the fluid with a larger pump.
Pump work, as well as electricity consumption, become unreasonable, at some point when the water becomes too turbulent. In extreme cases, there can be an occurrence of erosion corrosion because of too turbulent flow. Too short circuit lengths tend to run in laminar flow in which there is no exchange of heat quite and a slight turbulent flow. A nuisance of slow flow is the possibility of collecting air bubbles in some tubes, thereby reducing the effectiveness or even blocking the flow. The goal is to have the fluid coming out of the tube within 10-15 degrees of the temperature that it went in and move at a slight turbulent flow as it passes through.
The different types of radiant heaters include:
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 is the go-to method of radiant heating for floor heating. Usually, this method of radiant heating system is minimally demanding maintenance wise, long lasting than its alternatives. However, to run them, they can cost a pretty penny due to the ever increasing cost of electricity.
Usually, they are more energy-efficient when they are used in areas that are small like a driveway or bathroom.
These types of radiant heating systems make use of a boiler to pump heated water through a pipe network throughout the entire house or floor. They can also be installed in ceilings and walls. While their operation price is very low than that of electrical heating systems, their pipes are susceptible to bursting or leaking.
For the heating of an entire house, hydronic radiant heating systems are radiant heating systems that are the most energy-efficient and cost-effective.
These types of radiant heating systems make use of heated air for the transfer of heat. Among the three standard heating systems, these are the least efficient. Their lack of efficiency is because of the fact that the capacity of air to carry and retain heat is the least. This is so especially in an older house with potentially more areas having air leaks or cracks that can allow for the wastage of the heat.
Some of the examples of radiant heating systems include:
These radiant heating systems use infrared radiation to warm the objects and people in a room directly. This heating method is much more comfortable and efficient than heating systems that heat the air; with the heat that comes from the ground up, the room’s temperature will feel much more consistent without any cold spots or drafts.
The concept behind the radiant floor heating system is that the thermal energy is radiated off of the surface, the same way heat from a burner on the stove can be felt several inches to feet away. Therefore since the system does not directly warm the air, it makes a person and the objects in the room feel warmer.
There are two classes of radiant floor heating systems which are wet and dry installations. It must be noted that this classification is not dependent on the heat transfer medium: the words dry and wet do not make reference to electrical resistance or hydronic piping.
This type of radiant floor heating installation is the oldest. This installation is more expensive than a dry one because mats, electrical cables, or hydronic tubing are embedded in a concrete slab that is a thick or thin concrete subfloor. It takes more time for the radiant floor heating system to heat the floor and the air in the room, but the heating effect is preserved by the large thermal mass of concrete for several hours after the system is turned off.
The setup of this type of RFH is easier, less expensive, and the most convenient type. The installation of the mats, heating cables or tubing is done in a pocket of air under the floor, instead of getting embedded in concrete. This in turn will result in faster heating than in a wet installation. This configuration needs to operate at a high temperature because it is not embedded in the material of the floor.
The types of radiant floor heating systems include:
These are the oldest types of radiant heaters. Air heaters are a little less efficient than other types and therefore not common. Instead of pumping air directly beneath the floor, the air that is heated is circulated through a series of tubes, the same way water is used.
The only difference is that air is lightweight and can be easily pushed through the tubes, so it can be a faster system. With this system, a heater is used, but rather than pushing the air through the ducts to vents, the air will be pushed through tubes or ducts in the floor, heating it. To be energy-efficient, it could be challenging for this system. However, since the heaters are embedded along with ducts in the floor, they don’t use much space in general; there is no need for a large furnace or boiler.
There is a need to make sure that the system is well sealed and well closed, and its installation needs to be made with a wet installation. The heaters can be placed anywhere for easy access and are housed in boxes within the concrete. This makes repairs and maintenance easier if they are required. Air heated floor systems are capable of being used in all types of buildings and with all floors 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.
Over the installation, concrete is then poured in the normal manner of creating a slab. Curing will start after three days and the complete process will take roughly three weeks. There is a possibility of retrofitting, but still the use of poured concrete is required as well as wet installation. With this type of system, dry installations may not be possible.
In electronic radiant floor heating systems, cables or wires, and occasionally mats in small spaces are installed in either a dry or wet installation beneath the flooring. The wires are connected directly to the home’s electricity and a thermostat is used to control the floor.
There are a few components that the system is made up of, such as a heating element – either wires or a mat, in floor sensors and the thermostat. For spaces that are small, mats embedded with the wires can be laid in a thin mortar layer, with the mats cut to fit the area. In large spaces, the wires are looped usually about 3-inches apart throughout the space, also being embedded in a thin mortar layer.
The system uses a type of heat-conducting plastic to help transfer heat from the cables to the floor above. Electric radiant floor heating systems are a little faster to use, since the cables start to generate warmth immediately, instead of having water or air heated first, then pumped through the entire system. Their installation can be made under any type of flooring with no issue, and the cables will not end up raising the floor the way that a thicker system would, because they are thin.
Both the installation and running of electric radiant heaters is more expensive. They can be faster to install and less invasive, especially in small spaces such as bathrooms. They can be used often as a form of supplemental heat.
These types of systems make use of hot water to warm a building and are the most efficient of all three systems. Hydronic radiant floor heating systems consist of a hot water heater or a boiler that warms the water. A series of PEX tubes embedded beneath the floor in either a dry or wet installation is used to feed the water. The hot water that circulates through the tubes is responsible for warming the floor above. The system is totally closed, allowing the water to run in an open system or loop. The installation of this type of radiant heating system can be made beneath any type of flooring and is also very efficient. It consumes less energy than a hot furnace that is traditionally forced, saving energy bills up to 30 %. It consists of various types of installations available, therefore it can be retrofitted.
The flooring material extremely influences the way radiant floor heating performs. Thermally conductive materials can enhance performance, while insulating materials are detrimental. However, this does not imply the avoidance of insulation – just make sure it does not get installed where it can block the transfer of heat between the radiant floor system and indoor spaces. Because of its thermal conductivity and high storage capacity, the most effective covering material for radiant floor heating is ceramic tile. Other materials like vinyl and linoleum sheets offer too much insulation, therefore reducing the efficiency of a system. Wood floors can conduct the heat quite well, but laminated wood flooring is preferred over solid wood, which is prone to easily dry and contract.
The floor is not the only area where a radiant heating system can be installed. A radiant heating system can also be installed on walls, as well as ceilings. Under-floor radiant heating is the method that is probably the most efficient since there is an even distribution of heat within the living space.
An installation of radiant panels can be made on walls to heat small rooms. But these tend to be less effective than ceilings or floors since it's difficult to cover large spaces. However, radiant ceiling heating systems can often be even more efficient than radiant floor heating systems since it's only hot air that raises, not heat itself. A radiant ceiling heating system can create a very comfortable room without needing to disturb the current flooring.
These types of radiant heaters are a newer addition to the market place and offer certain advantages. The chief advantage is that they do not take up any floor space and are slim. The radiant heat that they offer is more balanced from head to toe. Considering safety, these types of radiant heaters are also much better for homes with small children and/ or pets.
In these types of radiant heaters, the installation of the radiant heat panels is made in the ceiling. These radiant panels will then radiate heat out towards objects and people beneath. When a radiant ceiling is heated to only a few degrees more than the other surfaces that surround it, it immediately emits infrared heat in every direction.
These radiations will directly warm any object or surface in the area surrounding it, regardless of their being up or down.
These types of radiant heaters tend to have a smaller size than their wall mounted counterparts and can be easily moved from one room to the other, which is a real advantage if the only option is to take the heat to different points. These are also ideal in the provision of heat in very small spaces.
This chapter will discuss the applications and benefits of radiant heaters.
Radiant floor heating systems offer a lot of benefits. Because they don’t heat the air, the room temperature will feel more consistent from the floor to the ceiling, because the heat is not leaving cold areas on the ground. More comfort is felt in a room with radiant floor heating, and in many cases, it does not use as much energy so it reduces the heating bills. It is capable of working under a variety of flooring types, so it will not detract from a home’s beauty. And since it does not blow air through ducts, there are only fewer allergens that get circulated through the house. Radiant floor heating systems are easy to run.
Hydronic radiant floor heating systems help create more even heat through the entire building at a lower cost. Therefore they make sense for larger businesses and companies that are in ownership of their own facilities, instead of renting out space. These types of floor heating systems are capable of making it more comfortable for employees and also for customers in retail settings, with no cold or hot spots to deal with.
Electric radiant floor heating systems are versatile and therefore allow for both wet and dry installations, and also retrofits of many kinds. They can be quickly installed and put to use almost immediately, making them a good choice for large buildings that may consist of individual offices that need to be heated and controlled.
Free standing radiant heaters can be easily moved from one place to the other.
However, the benefits of radiant heaters far outweigh the radiant heaters’ drawbacks.
A radiant heater works much more efficiently when it is placed in an area that is near to the objects or people that need to stay warm. Here, if the room is open or closed, it does not matter as much, since it is the individual objects or persons that are being targeted to be heated rather than the air itself.
Also since radiant heaters do not rely on blown air to heat a space, hence no drafts will be caused, they can be real health-savers for persons who are suffering from asthma, allergies, or other breathing-related issues. For rooms that serve specific purposes, have smaller sizes, and may go for long periods of time without being used during the day or night, radiant heaters tend to be ideal choices. Good indoor examples of this type of room are bathrooms and bedrooms.
Radiant heaters can be an excellent choice that is energy efficient in garages, basements, storage shades that need temperature control, workshops and patios.
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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