How To: Install Underfloor Heating

Underfloor heating is the height of luxury! It’s also suitable for any room in the home – not just the bathroom. Aside from the wonderful feeling of walking on warm floors, it also distributes heat evenly and consistently throughout the home.

Our step-by-step guide will show you how to install underfloor heating. First, let's talk about the different types of underfloor heating available, installation differs according to the type you choose.

Wet Underfloor Heating

Wet or water systems connect to the central heating system via a network of pipes which run hot water beneath the feet. It uses continuous plastic pipes, so there are no joints. This means no leaks!

Any type of boiler can be used for this system, as long as it has sufficient capacity.

All our systems are supplied with everything you need to install your wet underfloor heating and will heat a floor of 15m2. Our kits are all made from the highest quality components and are designed to achieve optimal performance in areas of high heat loss. They even come with a 25-year guarantee!

Electric/Dry Underfloor Heating

As the name suggests, an electric system uses electricity to warm the floor via heating cables fitted underneath. There are three types of ‘dry’ systems:

Loose wire

This is best suited for stone or tile floors and ideal for irregular and awkward-shaped floor areas, such as a small bathroom. It can also be used in large areas using a carrier de-coupling mat. The loose cable is only 3mm thick and is adhered to the floor using fixing tape following the spacings given in the installation guide.

Matting

This system is designed for installation directly below tiles and stone flooring and is great for large or more regular-shaped rooms. Read the instructions carefully before you begin your installation.

Foil Mat

This system has been designed for use under laminate and manufactured hardwood flooring. It has a foil heat exchanger for even heat distribution through the floor surface.

It is important to install underlay onto the floor before laying the foil mat. Our underlay is a 6mm thick Depron Foam board that is laid out and fitted over the entire floor area. The thin heating cables then bed into the underlay with the foil heat exchanger on top.

Can I Install Underfloor Heating Myself?

If you are a DIY enthusiast, it’s possible to install underfloor heating yourself. However, this is a technical task that involves plumbing and electrics so should not be attempted by a beginner. For that reason, you should hire a qualified professional if you have little DIY experience.

Even you if decide to install it yourself, we still strongly advise discussing the project with an underfloor heating expert as they can help with planning the installation of the system. If you are installing electric underfloor heating, you will need an electrician to do the final connections once installed.

How to Install Wet Underfloor Heating

Step 1: Prep the subfloor

Before you lay the heating pipes, you should clean the subfloor thoroughly. This will get rid of any debris or anything that could potentially damage the pipes. You should also lay a damp-proof membrane to help prevent dampness and rust.

Step 2: Insulate the floor

Laying floor insulation/underlay will make your underfloor heating as cost-effective and as economical as possible. Make sure the boards are fitted neatly and according to the manufacturer’s instructions, and that the seams are taped.

Step 3: Install the manifold

The manifold is a vital component of any wet underfloor heating system. It is essentially the control centre of your underfloor heating, allowing you to maintain the temperature and water flow. You must install the manifold first, as this is what the pipe loop is connected to in a particular room. You will need to find a suitable location and attach it to a strong enough wall to support both the manifold itself and the connecting pipes. Ideally, it should be located as centrally as possible in the building.

Ensure the underfloor heating pipes are connected to the flow side of the manifold; an arrow will mark this.

Step 4: Laying the pipe

The pipe can then be fitted by snaking it from the manifold to the furthest part of the room and back again. Ensure that the space is correct between each run of piping. 20cm between each run will suffice. It is important to leave space between the runs as it allows the heat to be evenly distributed.

For bigger rooms, you will need multiple loops of piping to cover the entire surface of the floor. Once the pipe has been laid, make sure it is properly clipped in.

Step 5: Do a pressure test

Check the system’s pressure to identify any leaks in the manifold, pipework, or joints.

Step 6: Lay the screed

The system needs to be kept under pressure whilst laying the screed and whilst it is drying. This will stop it from becoming too tight around the pipework.

Step 7: Connect the boiler pump and thermostat

Connect the manifold to the boiler pump and double-check that the system is working correctly. Finally, connect the thermostat to the underfloor heating.

Image by senivpetro on Freepik

How to Install Electric Underfloor Heating

Step 1: Measure up

Using a tape measure, take the measurements of the room and note them down on paper. It also helps to draw a rough sketch of the room to prevent any mistakes.

Once you have your sketch and measurements, you can calculate the area that will need to be covered by the heating. Remember to subtract the areas where fixtures will be and leave around 40 to 50mm around the edge of the room. Your heating will not be laid flush with the wall, so it’s also recommended that you subtract 10% from your final calculation.

If are going to be laying your UFH onto an existing floor but intend to remove any fixtures such as toilets or bath panels before laying your UFH, mark these areas first. Draw an outline on the floor around the fixture with a permanent marker to stop you from laying matting where the fixture will be.

Step 2: Insulate the floor

Laying down Insulation will make your electric underfloor heating run much more efficiently, saving you money.

Step 3: Find the power source

Find the power source for the UFH and make a hole in the wall for the cabling. We strongly recommend asking an electrician to help you with this.

Cut a recess into the floor/insulation board to accommodate the pipes that will encase the floor sensor and power cables. This is vital as the power end of the matting will be much thicker than the rest so it will need something to fit into.

Once cut away, clean the area thoroughly to remove any dust, grease, and debris.

Step 4: Test your UFH

Before you lay down your heating, give it a quick resistance test with a multimeter to make sure that it’s working. A multimeter is a test tool that can be used to measure voltage, current, and resistance.

Once you take it out of the packaging, get the multimeter on it. The measurement you are looking for will be between the live and neutral cables and it should match up with the data sheet that comes with the underfloor heating. If it does, you’re good to go! If not, you may need to return the heating. Ask an electrician for help if you are unsure about doing this resistance test.

Step 5: Let’s get rolling!

You are now set to lay your underfloor heating. If you are installing matting, put the power end down by the recess you’ve cut and start rolling the heating out. If you reach an obstacle such as a wall or bathroom fixture, you will need to cut the mesh/matting. However, DO NOT CUT THE WIRE. Step back and take note of where the wire is within the mesh of the matting and figure out where your cut needs to be able to flip the mat and continue. The direction in which you want to flip the mat will define where the cut should go.

The ‘U’ bends in the wire at the edge of the matting will open up to form a continuous link once the mesh below has been cut, allowing you to turn the mat back on itself and continue rolling.

Once you’ve done this you can roll out the mat again. If you reach another obstacle, repeat the above process. After all cuts have been made and the heating is fully rolled out, the whole room should be covered if your calculations were correct.

If you are installing loose wire heating, simply adhere it to the floor using fixing tape and following the spacings given in the installation guide.

Step 6: Position the floor sensor

Once the underfloor heating has been laid, you need to get the floor sensor or probe in place so that the thermostat can read the temperature. It’s always best to place the sensor as close to the centre of the elements as possible as this will give the most accurate reading - some tape will help keep it in place. You should also consider the following:

1. The probe cannot cross any of the wires, as this will give a false reading.
2. It should be placed underneath the mesh, not laid on top.
3. It must be at least 150mm away from the wall.
4. Link the probe as close to the power source as possible.
5. The probe is quite thick, so cut a recess for it as you did with the power end of the heating.

Step 7: Test again

Now everything is in place, test it again with the multimeter. If the reading is good, congratulations - you’ve successfully installed underfloor heating! You will then need to hire a qualified electrician to make the final connections before laying down your chosen flooring.

Once you’ve installed your underfloor heating, you will be amazed by the difference it makes in keeping your home cosy and your toes toasty! To buy the right underfloor heating for your space, shop online or visit one of our showrooms. For showroom opening times and locations, click here.