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Wet Underfloor Heating Installation: Everything You Need to Know

If you’re thinking about adding wet underfloor heating to your property, you likely have some burning questions about this popular and cost-effective system.

Here at PlumbNation, we’re experts in all things plumbing and heating and have been since 2007. In this article, we’ll guide you through everything you need to know about wet underfloor heating, including some top-notch advice about installation.

Want to know more? It’s all here - so keep reading!

How does wet underfloor heating work?

Wet underfloor heating

Wet underfloor heating works by distributing warm water from a boiler to a circuit of polythene pipes via a manifold. The heat is controlled and monitored by thermostats which help maintain a consistent temperature throughout the property.

As well as using traditional heat sources, underfloor heating can also be used with renewable energy sources, including solar panels.

What’s more, they heat a room much better than a radiator can. Radiators heat the air above and around them to a much higher temperature. This causes the heat to rise, resulting in the floor being the coolest part of the room. Underfloor heating ensures there are no cold spots by evenly distributing heat - no more huddling by the radiator after a shower!

You may also hear wet underfloor heating referred to as:

  • Hydronic underfloor heating
  • Warm water underfloor heating
  • Gas underfloor heating
  • Wet systems

Hiring a professional vs installing a wet underfloor heating system yourself

Hiring a professional wet underfloor

Whilst a competent DIY enthusiast can install the heating themselves, it is a technical project and requires a good skill level. It is certainly not a job for a beginner. Seeking professional advice and assistance is strongly encouraged.

It is advisable to discuss the project with an underfloor heating expert as they can help with planning the installation of the system.

It is also highly recommended that you hire a qualified plumber, as they will lay the pipes and connect them to the boiler correctly.

Furthermore, you should use a qualified electrician who holds a Part P or NICEIC certified plumber to ensure the system is correctly connected to your mains electricity and the sensor on your heating controls.

What you need to install a wet underfloor heating system

What you need wet underfloor

Materials

Here are some of the important materials needed to install underfloor heating (UFH):

  • Heating manifold : This is the system’s central hub as it distributes warm water to each of the UFH zones. These come in many different sizes, so you will need to find one which is suitable for your home.
  • PEX pipes and AL-PEX pipes : They can withstand temperatures of up to 95°C so they can easily deal with the temperatures produced in the system. They are designed and guaranteed to last at least 50 years. This gives the homeowner peace of mind as they are of high quality and built to last.
  • Screed : This is a type of mortar commonly used for flooring. It is smooth in texture and is usually made from fine grains of sand. This smoothness makes it ideal for underfloor heating as the final layers such as carpet, laminate, or tiled floors can be placed above it.

These items and other underfloor heating accessories you’ll need to install underfloor heating can be found at PlumbNation.

Tools

If you are embarking on the project alone or assisting a trained professional, you will need these essential plumbing tools at your disposal.

  • Pipe cutter : A good quality cutter will cut cleanly through the pipe with a reduced chance of deformation.
  • Pipe fixing clips : These are used to secure the pipe when installed on top of the underfloor heating insulation.
  • Tape measure : Essential when accurately measuring the distance between your pipes as this will help spread the heat evenly across the particular room.
  • Pipe re-rounding tool : This is used after the pipework has been cut. It will ensure that the cut end is perfectly spherical and that the pipe will fit perfectly.

What type of insulation do you need for underfloor heating?

Insulation is a very important consideration for underfloor heating. For the most effective result, it should be fitted below the heating pipes to prevent the heat from going downwards. This means the heat will rise and warm the room more effectively.

A recommended material is Expanded Polystrene (EPS) which is both popular and cost-effective. It is made from polystyrene foam beads. These beads have little air pockets that make EPS 90% air, so they are very lightweight. This means it is perfectly safe and very effective.

How to install wet underfloor heating systems

Step 1: Clean the subfloor

Before you lay down the heating pipes, you are advised to clean the subfloor thoroughly. The reason for this is that, whilst the pipes are very durable, cleaning the floor will rid them of any sharp objects or edges that could potentially damage them.

You should also lay down a damp-proof membrane as this will help prevent dampness from occurring and stop any corrosion.

Step 2: Install floor insulation

Laying floor insulation is vital in making the heating as cost-effective and as beneficial as possible.

Make sure the boards are fitted neatly and that the seams are taped. The heat rises, so only a minimal amount is lost beneath the floor.

Step 3: Install the manifold

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.

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. Space between the runs is essential as it allows the heat to be evenly distributed.

For larger 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: 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. Read our guide on underfloor heating boiler requirements if you need further guidance on which boilers work with UFH. Finally, connect the thermostat to the underfloor heating.

How long does it take to install a wet underfloor heating system?

Time Underfloor Heating

This very much depends on both the size and the ease of the installation. Generally, most projects will take between one and two days. Larger homes or commercial installations can take upwards of five days.

The time it takes will also depend on how easy it is to access the area where underfloor heating is to be installed. If the house is empty, it will take less time to install than if it is occupied.

Underfloor heating system estimated cost

The cost of the heating depends on several factors, including the size of your house, the age of the property, the number of rooms you are fitting in, and the type of underfloor heating installation you are getting.

On average, you can expect to pay anywhere between £500 and upwards of £8,000 to install underfloor heating systems.

How to choose a qualified wet underfloor heating installer

If you would like a professional to carry out the work, many registered and qualified installers are available throughout the UK who will complete the installation for you.

A quick internet search is all you’ll need to locate registered installers in your area who will help plan and fit the system as safely and effectively as possible. It’s essential to do your research when finding the best installer for you. Remember that if a price looks too good to be true, it probably is.

Compare prices and reviews to make sure you’re getting the best installer. Don’t risk having to pay extra to have your underfloor heating fixed!

FAQs

What type of flooring is best for wet underfloor heating systems?

A benefit of underfloor heating is that it is suitable for a wide range of surfaces, such as carpet, vinyl, wood and laminate flooring.

However, the most effective types of flooring are hard surfaces such as stone, ceramic tiles or concrete floors. These are the most thermally conductive and offer the best heat transfer.

Is it expensive to run wet underfloor heating?

One of the significant advantages of wet underfloor heating is that it can save money in the long run by making the home energy efficient.

They work with low water temperatures, reducing energy consumption and heating costs.

How long does a wet underfloor heating system last?

To fit with the DIN 4726 industry standard, the piping used in the system must have a projected lifespan of at least 50 years.

However, it is possible that some systems could feasibly last over 100 years when properly maintained.

Do wet underfloor heating systems need servicing?

Whist the heating system is largely maintenance-free, a yearly service is recommended. Servicing allows a professional to check and correct for any signs of failure.

They can also offer the homeowner tips on how to maximise their heating efficiency.

How do you find a leak in a wet underfloor heating system?

There are a number of methods that you or a trained professional can use to detect leaks in the system.

Firstly, it is recommended to do a visual check and see if the leak can be detected by the human eye. If this is not possible, then many companies have access to thermal imaging, which allows them to detect any significant temperature changes, which could point them to the source of the leak.

Another method used is tracer gas. This harmless substance is passed through the system. If any escapes, it will indicate where the leak is coming from.

Keep your home warm with wet underfloor heating

Water underfloor heating systems can be a beneficial and cost-effective addition to your home. They are more energy-efficient than a standard radiator. Wet systems are virtually maintenance-free and the piping is guaranteed to last at least 50 years.

They work with much lower water temperatures, reducing your energy consumption and heating costs. It is a far cheaper option than electric underfloor heating in terms of running costs.

If you choose to proceed with an underfloor heating installation for your home, it is worth always seeking expert advice in the planning and installation, even if you possess high levels of DIY skills.

Read our guide on electric vs water underfloor heating for more guidance on the correct type of UFH for your home.