Underfloor Heating: Thermostat Wiring

What You'll Need
Wire cutters

Installing underfloor heating is a great way of warming a room without wasting energy, but you will need to wire up an underfloor heating thermostat in order to get the most from your new device. These thermostats control the amount of heat which passes through your underfloor, rather than the amount which enters your room, so you must be careful when using your underfloor heating thermostat. Fitting one will not be too difficult, and while you can pay a professional to do the job for you, you should also try installing one yourself in order to save money. Follow a few simple tips to get the job done quickly and efficiently.

Step 1 - Preparation

Before you proceed with your wiring, you need to check that you have the right thermostat for your system. Some underfloor heating wiring will only have two wires, while there are many underfloor heating thermostats which require a three-wire system to function. Ensure that your two devices are compatible before you attempt wiring them together. You should also check that your electricity and water supplies are turned off at the main valve and board, and there is no problem with the wiring itself. Once you have ensured compatibility, and turned off all your electricity sources, you are ready to proceed.

Step 2 - The Wiring

If you are replacing an old underfloor heating thermostat, then you should have no problems in simply taking off the old thermostat, and installing the new one using the old wires. If you don't have a heating system in the room, then you will need to get the wires from your heater, and make a hole in the wall through which the wires can be pushed. Heater wires should be connected to a pigtail grounding device, check your system's instruction manual for details of how this is done. When the heater is wired, trail the wiring through the wall into the relevant room.

Step 3 - The Thermostat

Assuming that you now have the wiring in place, remove the mounting plate from the back of the thermostat, and push your wiring through the hole. Don't pull to strenuously, as the wire needs to be fully connected to the heater. Mount the wall plate in position using the screwdriver, and then cut down the wires to an appropriate length, taking care to trim back just enough insulation to cover the terminals of your thermostat. Take the thermostat and unscrew the terminals. Check the manual to ensure that you know which wire goes where. Place the wire in the holes make by lifting up the screw, and then tighten this down again using your screwdriver. Ensure that the wire cannot fall out.

Step 4 - Finishing

Once the wires have been connected, you can install the thermostat into the wall. Push any excess wiring back through the wall plate hole, and then mount the thermostat onto the plate. Screw in to finish, and then turn on the power supply to ensure that everything is correctly wired and working. When you are satisfied, you can program the thermostat, and leave it to do its job.