Concrete Floor Radiant Heating Types, Benefits, Installation Tips

Hydronic radiant floor heatingHydronic radiant floor heating

How and why to install concrete floor radiant heating. Radiant floor heat in concrete slabs for your home or driveway heating.

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Types and benefits

There are two types of concrete floor radiant heating systems; one uses a large thermal mass of a concrete slab floor while the other is a lightweight slab over a wooden subfloor.

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.

The radiant floor heating temperature in slabs is consistent and easy to control - there are no drafts and uncomfortable air blowing into your face.

In hydronic heating, hot water circulates through the heating pipes, so these are known as "wet installations."

Electric heating can also be used in radiant heating, and it is cost-effective as long as it heats the thick concrete floor, with affordable electricity rates, of course. A thicker floor will store the heat longer and make your house comfortable for hours without further electrical input.

Radiant heat in concrete slabs is retained, so the open doors or large windows 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.

Installing concrete floor radiant heating

The best time to install concrete floor heating is when installing a concrete slab.

Why?

Installing a concrete floor radiant heating is not a hard DIY project, but it needs some skills, knowledge, and the right tools. This is also known as the slab-on-grade installation.

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, a 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.

Covering for the radiant floor heating

The covering that goes on the cement floor also has a significant impact on the heat transfer. The tile floor, for example, has much better heat transfer than the carpet. 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.

Installing the thin-slab floor radiant heating system

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The thin-slab concrete floor radiant heating system is a better choice than the above solution. A radiant heating system is installed above the larger slab if you already have an existing concrete floor. 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.

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.

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 the thick concrete floor radiant heating systems is their slow thermal response time.

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