Electric radiant heat mats with wall-mounted thermostats are simple to install under new tile floors. The following steps will explain the process of installing an electric radiant floor heating system under new tile floors.
1Install a tile backer board on the floor. Secure it to the existing subfloor with thin-set mortar and cement board screws or nails.
2Keep these tips in mind when trying to decide the size of mat you will need:
- Do not install the mat under a vanity cabinet or sink
- Place the mat 4 inches away from walls, showers or tubs, as well as the toilet wax ring
- Do not ever overlap the cable
- Do not leave large gaps between the mats.
3Check the wire with a continuity tester.
4Install an electrical outlet box 5ft. up in the wall right next to where the wiring leads from the mat will terminate. New wiring should be run from the circuit breaker panel.
5Mark the path of the thick power lead between the mat and the wall cavity. Chisel a shallow trench into the floor. Notch the bottom plate so that two conduits can hold the power lead and the wires for the thermostat sensing bulb.
6Draw the tile layout lines. Choose a tile that is at least 6 inches square, so each tile will span two or more sections of cable.
7Lay down the mat in the right place.
8Install the mat by using a cement board and double faced tape to secure it. Use hot glue to secure the mat. Do not leave humps or loose edges because this could snag the notched trowel when you are applying the thin-set mortar. Some radiant heat mats can be mortared and tiled in one step, while others must be mortared in place first, given time to dry and then tiled. Follow the manufacturer’s instructions.
9Use a continuity tester to check the mat.
10Run the power lead cables and the thermostat.
11Take two pieces of ½” electrical metal tubing long enough to run from the floor to the electrical box and install conduit connectors to both ends. Push the power lead cable through one length of conduit. The power lead cable needs to be hot glued into the groove. Push the thermostat wires through the second conduit. Weave it 12 inches into the mat. Nail metal protective plates over the bottom plate. This will protect the wires and cables.
12The mortar can be spread over a 5 to 10 sq. ft. area of floor. The flat side of the trowel needs to be pressed firmly through the mat with the cement board. Develop a flat, uniform layer by floating the trowel across the tops of the cable. Use the notched side to comb the mortar to create 3/8 x ¼ inch trowels. Skim the trowel over the cable.
13Lay the tile and tap it into place. Perform two resistance tests to make sure you have not damaged the cable while installing tile.
14As soon as the mortar has dried, grout the joints.
15Connect the power lead and the thermostat wire to the thermostat by using the manufacturer’s instructions.
Enjoy your new electric radian floor heating system.