Here is an overview on how to install your own under-floor loose wire radiant heating system. This type of heating system is a great supplement to your whole-house heating system. Or do you have a "cold room"... a space that never seems to warm up enough? Or do you want to install tile on your kitchen or bath floor but are concerned that it will be cold in the winter? An under-floor system can keep these areas warmer at a lower cost and greater comfort than any other type of heating unit!
1) Take measurements and plan wiring locations carefully
Any type of installation requires figuring out exactly how much material you will need to do the job. It is no different with an under-floor heating project. As noted in the diagram below, you will first need to measure the area you want to heat, excluding any furniture or fittings so that you purchase the right amount of product for your project.
It is important to avoid placing the radiant heating wire underneath areas where you plan to install fixed furniture, such as cabinets. You can place the heating wire close to toe kicks or the shower/tub enclosure, but leave a little room around toilet drains (so it isn't underneath the toilet) and walls are needed.
(If you have an existing floor plan and need a little advice, the experienced staff at Warmup will be happy to recommend the best option for your floor.
2) Decide where to install your thermostat...
The thermostat is the "heart" of your radiant heating system, controlling the power to the heating wires and also regulating the temperature of the floor. All wiring for your radiant heating system either runs to it or from it. Most people will install their thermostat near the entryway of the room they are heating, near the light switches. However, anywhere you install it is fine as long as the area is dry and unobstructed.
In some cases, the location may need to be based on the layout of your home and the location of the main circuit board. Consult an electrician if you need assistance with the specifics. Of course, any electrician would be glad to do the final wiring for your project! (If you're interested in seeing what a state-of-the-art floor heating thermostat looks like, Warmup offers an exciting new energy efficient, programmable floor heating thermostat called the 3IE. See pictures below.)
Floor heating thermostats usually require a double-gang box with two 1/2" conduits down to the floor level... one for the heating wire and one for the sensor wire.
Protect the wire with a thinset mortar coating...
Using a flat trowel, cover your wiring system completely with either a floor leveler or a modified thinset. In this example the contractor is using a polymer-modified thinset mortar. (We often use MAPEI FLEX or CBP Versabond for our installations.) You can reduce that layer to a strict minimum, but it will provide for an easier tile job. In any event, you must always make sure that the wires are completely imbedded in these compounds so as not to be exposed to the air and over-heat. Do not attempt to set tile into this protective coat!
After it has cured (a few hours to overnight depending on thickness and the manufacturer's suggestions), start laying down the tiles or other flooring) as normal.