If you have ever wanted to try a heated flooring project, but were apprehensive about the process, this information is for you. Radiant floor heating technology is very old and has never gone away. If done correctly, radiant floor heating can heat your entire home.
We will discuss the common floor heating methods commonly in use and how to install them. As a side note, there are floor heating systems specially designed for use with floating floors, such as engineered hardwood, laminate, and vinyl.
Today, however, we will discuss radiant floor heating with tile floors.
Installing Electric Mat Under Tile
The electric mat system is the easiest type of floor heating to install. This design takes a rubber or plastic mat that can be utilized in projects where cement backer board or concrete is already present. These electric mat systems may come in a roll, sheet, or a self-contained membrane. This system is ideal as part of a remodel, or as a small weekend project.
- To begin, measure out the area you intend to heat. The mat(s) should be approximately the same size as the space or smaller. Lay out the mat(s) onto the space and ensure it will stay the minimum distance from any pipes, walls, or fixtures. This distance will vary from manufacturer to manufacturer, so just follow the directions.
- Next, temporarily tape the mat to the floor and connect the included sensor to the thermostat wires. Most systems will use standard 110-volt service, but some will use 220 volt service, so ensure you have access.
- Next, mount the thermostat. For most designs, the mat will now be laid across the backer board and secured to the floor using thin-set mortar. If your floor is severely out of level you can also use a floor leveling compound.
Pro Tip. Do not attempt to lay tile directly onto the wire without the benefit of the mat. This will not only make leveling the tiles very difficult but can also endanger the wire.
- Now that the mat is secure, you can lay your tiles. As mentioned previously, be careful not to install electric floor heating where a fixture, such as a toilet or a bathtub, is located. Keep the wire away from baseboards, floor registers, or any other obstruction. The manufacturer of your materials will indicate what this distance will be, so follow them closely to avoid problems later.
As with a single wire system, you can use most any type of tile, such as porcelain, ceramic, or slate, keeping in mind not to drop the tiles onto the mat. Since the mats are typically more delicate than a single wire system, use caution when placing the tile to prevent any sharp edges from contacting the wire within the mat.
Installing Electric Single Wire Under Tile
The electric single-wire system takes the mat system and essentially makes it more customizable. Where electric mats already contain conductive wiring, electric single wire designs do not. Small, hard to get to spaces are perfect for this type of floor heating.
Another popular feature of the single-wire system is the ability to lat your tile directly onto the mat. With standard mat systems, the mat and wire must be adhered to the backer board with staples or thinset mortar before installing the tiles. The single wire method not only eliminates the thin-set, but the backer board as well. This makes the single-wire system adaptable for nearly any application.
Most of the single-wire systems available today are also promoted as able to reduce cracking in the mortar. This is because the mats used in this system are usually thicker and essentially break the normally present bond between the wooden subfloor and the cement backer board.
The idea is that since the wooden subfloor can move and flex independently from the tile, the grout used between the tiles will be much less likely to crack over time.
- To begin, measure out the area you intend to heat. The mat should be approximately the same size as the space, or slightly larger. Since this system works best in spaces that have irregular shapes, you can simply cut and shape the mat as needed. Some manufacturers suggest stapling the mat down, while others use tape, or even mortar to secure the mat to the subfloor.
- If you are installing electric floor heat as part of a new construction project, make note of where cabinetry or plumbing fixtures (such as a bathtub or vanity) will eventually be located and avoid these areas. Only install electric floor heating where you will physically walk and stand.
- Now that the mat is secure, the wire can be installed. Using the guides in the mat to secure the wire, wind the wire as directed in the instructions. Generally, the wire will weave around the mat evenly, but you can place the wire essentially anywhere you need heat. In most versions, you will need to chisel out a small channel in the floor between the sensor and the thermostat wires.
- The sensor contains electronics, and this channel will prevent the sensor from causing a hump in the tile. Be very careful not to lay the sensor directly over the wire when installing it. If the sensor is too near the wire, it will become too warm and prevent the thermostat from turning on.
- At this point the mat and wire are secured and ready for tile. Simply lay a bed of mortar directly on the mat, just as you would with cement backer board and install the tile normally.
Installing Hydronic Under Tile
A hydronic radiant floor heating system uses both electricity and liquid (usually water) to circulate heat. A hydronic system is installed under the floor just as an electric system, but instead of heating wires, a hydronic system utilizes tubing, called PEX. Hydronic systems are usually used when the structure is not on a concrete pad, or when the entire home will be heated using the system as a primary heat source.
A hydronic system is not installed directly under tiles like a similar electric system would be. The tubing used in this system is quite thick compared to the thin wires used in an electric system. Installing this tubing above the subfloor would cause transition problems when moving from room to room, so this system is installed under the subfloor.
- Before you begin, it is strongly recommended to test both the wiring and the tubing before installation. The wiring can be tested using a multimeter. To test the tubing, plug one end of the roll and install a pressure gage. Using an air compressor, pump approximately five pounds of air into the pressure gage. If the pressure does not fall for five minutes, the tubing is good.
- Measure out the space to be heated and avoid non-traffic areas, just as with an electric system. If the project is part of a remodel, remove the subfloor and route the tubing as directed by the manufacturer. This will usually involve one continuous loop that winds from one end of the space to the other.
Pro Tip. Even professional installers will usually involve the manufacturer of the materials in the design phase of the project. Hydronic systems are more complex than electric systems, so ensuring you have everything you need will make the process much easier.
- After the tubing has been routed and secured to the framing with special PEX clips, the tubing connections can be made. Hydronic systems need a separate water heater or boiler to heat the water to maintain the desired temperature. This connection is made via a manifold, which directs the water to the various zones. Make these connections using a special pex expander tool and PEX rings.
- After the tubing is secured and connected, the system can be connected to the thermostat. In a hydronic system, this connection is usually made by running the sensor wire up through the floor and wall to the thermostat connections.
If you must run the wire within one inch of the edge of the stud, use nail guards over the wires to protect them from errant nails or screws. You can now replace the subfloor and backer board. Make sure that any backer board screws are not long enough to penetrate the subfloor and puncture the tubing. You can now install your tiles normally without fear of damaging either the tubing or the wiring.
Everyone Loves Warm Floors
Most anyone who has experienced radiant floor heating has enjoyed the sensation of warm feet on a cold morning. Radiant floor heating technology has come a long way in recent years, making this type of project popular with homeowners of all types. Especially when used in conjunction with tile, radiant floor heating is an efficient and cost-effective feature to add to any home.