Explaining Radiant Heating

Date Published: May 6, 2024

We can all relate to those hot summer days when the sun is beating down on your car. You buckle up into the driver’s seat and the interior is red hot! This is all because the sun’s heat has travelled as radiant energy to the surfaces in your car.

This simple concept has been applied in the residential setting as a way to efficiently and effectively heat a home. It is known as radiant heating.

What Is Radiant Heating?

Radiant heating is a system that utilizes the energy radiated from a heated source to warm objects and surfaces within a space. Pipes or cables are run through designated zones of a building – either in floors, walls, ceilings or radiator units.

Then they are heated with water, steam, or electricity.  These pipes or cables radiate heat, which warms the surrounding surfaces, subsequently traveling into the living space. It is a common technique used as an alternative to HVAC-based heating methods, such as furnaces.

The Types of Residential Radiant Heating

Hydronic Radiant Floor Heating

This is one of the most common styles of radiant heating. Tubing (usually PEX or rubber) is installed in evenly spaced, winding curves under the floor of a designated area.

Hot water is then circulated through these pipes effectively warming the surrounding surfaces. The heat then radiates off of the surfaces into the air. And voila – you have a nice, warm room!

Hydronic heating

Image sourced from: https://www.downrighttile.com

When it comes to hydronic heating systems, there is more than one way to get the water heated and flowing through the pipes. The different systems are as follows:

  • Boilers – These devices are very common in households and use a fuel source – such as gas, propane, oil or electricity – to heat water or steam in a combustion chamber. Once sufficiently heated, the liquid or steam will release into the connected system of tubing out to heat the home. Newer wall mounted condensing boilers are more commonly seen today. They look like tankless water heaters and use the same technology, but they have a higher BTU output.

Tankless Boiler. Image sourced from: https://radiantfloorsinc.com/radiant-heat/

  • Geothermal Heat Pumps – This is a unique technique that uses the natural underground temperature of the earth to heat and cool the interior of the home. This involves burying a loop of piping below the frost line of the soil. The loop is filled with water combined with anti-freeze. The solution then circulates underground, absorbs the earth’s heat, then carries that heated liquid to a pump in the house, which distributes it throughout the house.
geothermal radiant heating

Geothermal Heating Technique. Image sourced from: https://www.infloor.com

  • Water Heater – In smaller apartments and ADUs, you will occasionally see the heater water lines come directly off of the domestic hot water heater. This is usually a high-efficiency tanked unit that has a higher output to feed the additional demand.

Hydronic Radiant Wall and Ceiling Heating

Radiant wall and ceiling heating systems use the same technology as in-floor heating, but instead in the walls and ceilings. These are constructed with tubes that wind back and forth across aluminum sheets (as shown below).

radiant heating wall panel

Image sourced from: https://www.energy.gov

Electric Radiant Heating Systems

This style of heating is similar to hydronic heating. It can be installed in the floor, walls or ceiling. But instead of tubes with flowing liquid, this system uses electrical heating cables.

Electric radiant heating is desirable to some because it does not pose the same leaking risks as hydronic heating. However, it can be a very costly way to heat a space. So, many people only use it as a supplemental heat source, or in small spaces, such as an add-on guest room or office.


The radiator system is one of the oldest methods used for heating residential homes. Radiators come in different shapes and sizes, but they are all generally constructed with heat-conductive metal and have “fins” that are designed to radiate heat.

As the diagram shows below, a radiator will be connected to a boiler, which sends steam or hot water to the radiator unit. The hot liquid then travels through radiator coils, heating up the fins to the desired temperature. Different styles of radiators include the classic column radiator (shown in the diagram below), single and double panel radiators, vertical radiators, and baseboard radiators.

Because of the classic aesthetic and the difficulty of changing the heating system in high-rise buildings, many of these radiators are still in use today.

radiant heating - radiator diagram

Image sourced from: https://modernize.com

The Pros Of Radiant Heating


Radiant heating systems are praised for their ability to evenly heat a space – especially in-floor systems. Also, many of them are split up into individual zones. So you can easily set the desired temperature for each particular zone.

Energy Efficiency

Radiant heating systems can be more energy efficient than forced-air systems, as they operate at lower temperatures and do not have duct losses. In addition, the ability to utilize zones allows you to choose which zones to heat without expending extra energy on unused spaces in the house.

This can result in reduced energy consumption overall and lower energy bills.

Space Saving

Radiant heat systems will take up less space than forced air systems. As discussed above, radiant heating is either installed in the floor, wall, ceiling, or some form of radiator. The heat is supplied through compact tubes or cables. This means that no bulky ductwork is needed.

Health Benefits

Radiant heating means that no air is being pushed. That means that no allergens, dust, germs, or odors are being moved throughout the home. That’s why many people who are extra sensitive to air contaminants find radiant heating to be the more favorable option.

The Cons

High Installation Costs

Upfront costs for radiant systems, especially hydronic, will generally be higher than HVAC configurations. Also, retrofitting any home with that type of equipment is very costly, as it requires major renovations. But keep in mind that the energy saved down the road could prove to make up for the initial investment.

Image sourced from: https://www.forbes.com

Slower Response Time

When dialing in a temperature change, radiant heat systems can take a bit more time than the forced air method. It takes time to heat up the source and subsequently radiate heat uniformly into a space.

Inspecting Radiant Heating Systems

Having a reliable heating source is a very important part of any residential Colorado home. That’s why our inspectors always take a good look at the heating equipment. This includes a visual assessment of all the accessible components, and an operational test, when possible.

Of course, a lot of these heating system components will be hidden under floors or behind walls or ceilings. However, our inspectors can utilize infrared scanning technology to determine whether or not the heating equipment is functioning properly.

The two photos below are infrared photos of radiant floor heating. As you can see, the temperature differentials are indicated by different colors. Yellow means warm, which indicates that these systems are working!

Here at Scott Home Inspection, we have been helping Colorado families live in safe, healthy and comfortable homes for 18+ years. And it would be our pleasure to help you! If you need a home inspection, feel free to visit us online to learn more, or contact us today!

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About the Author: Chris Kimmel

Chris Kimmel worked as an Associate Home Inspector for two years, handling numerous services including sewer scope inspections, pest inspections, mold air sample testing, radon testing, and water quality testing. Chris now works with Scott Home Inspection as a Content Writing Specialist.

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