Concrete Floor Radiant Heating: Types, Benefits and Installation Tips

Hydronic radiant floor heating

See the benefits of installing a concrete floor radiant heating system, including types, basic installation tips, and how to select the best flooring.

Concrete floor radiant heating: Things to consider

Types and differences

There are two main types of concrete floor radiant heating systems: electric and hydronic.

Electric radiant heating systems consist of electric heating cables or mats that are installed directly onto the concrete slab or in between layers of flooring. Electric radiant systems are typically easier and less expensive to install but can be more expensive to operate over time. When used with a thicker concrete floor, the floor will store the heat longer and make your house comfortable for hours without further electrical input.

Hydronic radiant heating systems use a network of plastic tubing to circulate hot water or other heating fluid through the concrete slab. These are known as "wet installations."

The water is heated by a boiler, which can be powered by electricity, gas, or oil.

Hydronic systems are more complex to install and require more space for piping and heating equipment, but they are generally more energy-efficient and can be more cost-effective in the long run.

The tubing is embedded in the concrete during construction or placed on top of the slab before the flooring is installed. Hydronic radiant systems are typically more expensive to install but can be more energy efficient and cost-effective to operate over time.

Both electric and hydronic radiant heating systems can be controlled with a thermostat, allowing you to adjust the temperature according to your preferences. They can also be used in conjunction with other heating systems, such as a furnace or heat pump, to provide supplemental heat as needed.

Concrete floor radiant heating systems can also be divided into systems that use a large thermal mass of a concrete slab floor and one with a lightweight slab over a wooden subfloor.

Due to the high heat capacity, the thick concrete slab system is perfect for storing the heat from solar heating systems, which have fluctuating heat output. The disadvantage of thick concrete floor radiant heating systems is their slow thermal response time.

Benefits

Here are some of the benefits of concrete floor radiant heating:

1. Energy Efficiency: Radiant floor heating is more energy efficient than traditional heating systems because it heats the room from the ground up. This means that the heat is distributed more evenly and effectively throughout the space, reducing the amount of energy required to maintain a comfortable temperature.
2. Comfort: Radiant heating provides a more comfortable heating experience compared to traditional heating systems. The heat is distributed evenly, eliminating hot and cold spots.
3. Improved air quality: Radiant heating systems differ from forced-air heating systems in that they do not spread dust, allergens, and other pollutants throughout the home. This can improve indoor air quality and reduce respiratory problems.
4. Space-saving: Radiant heating eliminates the need for bulky radiators or vents, freeing up valuable space in your home. This can be particularly beneficial in smaller spaces.
5. Durability: Concrete is a durable and long-lasting material, which means that a concrete floor with embedded heating elements or PEX tubes can last for many years with proper maintenance.
6. Increased home value: Radiant floor heating is considered a desirable feature among homebuyers, which can increase the resale value of a home.
7. Aesthetics: Radiant heating eliminates the need for unsightly radiators or vents, which can improve the overall aesthetics of your space.

Concrete radiant heating is an excellent option as the main heating system; it is the cheapest, saves energy, and it provides healthier and comfortable living. It is a perfect solution for residential homes.

Radiant heat in concrete slabs is retained, so when the  doors or large windows are open, it will not affect the temperature inside your home as much as with the forced air heating systems. A concrete floor with a high density (high R-value) insulation placed below the slab makes the floor one big radiator.

Concrete floor radiant heating - Basic installation tips

The installation of concrete floor heating can be more complex than traditional heating systems, and if you have some experience, skills, knowledge, and the right tools, it is not necessarily hard to install. The process involves installing a network of pipes or electric heating cables beneath the concrete floor, which can be time-consuming and may require some construction work.

The best time to install concrete floor heating (also known as the slab-on-grade installation) is when installing a concrete slab. It is also important to make sure that the concrete floor is properly insulated to prevent heat loss and optimize the system's energy efficiency.

Here is the video example: How to Install Radiant Floor Heat Tubing in a Slab On Grade.

If you are already paying for the installation of the slab, recommendation is to install the floor heating also, since the only cost is adding very affordable PEX tubing, plus labor, of course.

In this case, when installing the concrete floor heating for the whole house, there will be no need to buy pipes or heaters that will occupy your valuable home space.

PEX tubing is the best option for the installation, and once installed inside the concrete slab, it has to be protected against damage and transport the hot water freely.

During the concrete floor radiant heating installation, the reinforcement wire mesh should be adequately positioned in the slab area and before pouring the concrete.

Polyethylene vapor barrier and insulation are also needed for efficient heat distribution. PEX tubing is then attached either with the wire ties or special clips. The idea is to secure the tubing, and the best will be to follow the manufacturer's instructions.

PEX tubing will be looped inside the concrete floor, and the spacing between the loops will provide more or less heat. The recommendation is to keep the loops one foot apart to make the bending easier and ensure the unobstructed hot water flow.

The depth inside the concrete slab at which you will lay the PEX tubing will also determine whether to use hot water with a higher or lower temperature and how long it takes to heat the floor. The recommended concrete slab thickness should be between 4 and 6 inches.

The location for the most efficient and safest installation is somewhere in the middle of the concrete slab, and installation should be without any joints. Use the entire length of the tubing whenever you can, as there is always a possibility of leakage where the joints are.

With or without joints, a new floor radiant heating system should be checked before concrete is poured to see any defects in the system. This is done by using the air pressure of 50 psi, and the tubing must maintain the pressure for 24 h without leaking.

Is installing a thin-slab floor radiant heating system better?

The thin-slab concrete floor radiant heating system is a better choice than the above option.

Thin-slab floor radiant heating systems are typically installed on top of an existing floor or subfloor. You can pour the thin slab of concrete over the PEX tubing on the wooden flooring, allowing retrofitting over an existing concrete floor without raising the floor height significantly.

The heating elements can be embedded within a thin layer of concrete, gypsum, or other material, which provides a stable and durable foundation for the system.

As in the example above, the PEX tubing is secured to the wood subflooring, not to the reinforcing wire. The height of the thin slab of concrete is usually 1.5 inches or 38 mm, so the tubing must be installed tightly to the floor to prevent protrusion through the concrete.

What is the best flooring for concrete floor radiant heating?

The best flooring for concrete floor radiant heating systems depends on several factors, including the type of heating system, the size and location of the space, and personal preferences for aesthetics and durability. Here are some flooring options that are compatible with concrete floor radiant heating:

• Tile: Ceramic or porcelain tile is a popular choice for covering a radiant floor heating system because it conducts heat well, is water-resistant, and is durable. It's important to choose a tile with low thermal resistance to ensure efficient heat transfer.
• Natural stone: Like ceramic tile, natural stone is a good conductor of heat and can be used with radiant floor heating. Stone floors offer a natural, rustic look and are resistant to scratches and stains. Additionally, tile and stone can be more difficult to install than other flooring types, which can increase the overall cost of the flooring.
• Engineered wood: Unlike solid hardwood, engineered wood is less susceptible to warping or shrinking due to changes in temperature and humidity. It can be installed over the heating system and comes in a variety of colors and styles.
• Luxury Vinyl Tile (LVT): LVT is a popular choice for covering a radiant floor heating system because it's durable, waterproof, and has a low thermal resistance. Additionally, although LVT is designed to mimic the look of other flooring types, some users may not find it as convincing as the real thing.

Installing the insulation under the subflooring can control the efficiency of radiant heating. The recommendation is to buy and install the insulation with an R-value greater than the R-value of the floor covering, so heat can go up, not below.

It's important to note that some flooring materials, such as carpet and solid hardwood, may not be suitable for use with concrete floor radiant heating as they can insulate the heat and reduce the system's efficiency. It is recommended to work with a licensed professional to ensure proper installation and compatibility with your specific radiant floor heating system.

Conclusion

While concrete floor radiant heating can have higher upfront costs compared to traditional heating systems, it can provide significant long-term benefits in terms of energy efficiency, comfort, durability, and aesthetics.

It's important to work with a licensed professional to ensure proper installation and maintenance of your radiant heating system.