Collage of floor heating system installation to floor leveling

The thought of installing underfloor heating (UFH) fills homeowners with excitement. Increasing comfort in your home and using space effectively by removing radiators is a big draw to these systems. However, many challenges must be met when installing underfloor heating in old houses.

UFH offers the most comfortable and energy-efficient heating, but the difference between installing UFH in existing homes and new builds is like night and day. First, the assessment of existing infrastructures differs from that of a new build, and once we start installing, it’s challenging to work out where and how to run the pipes based on space limitations and existing architecture.

This in-depth article unravels the process of installing underfloor heating in existing houses. Keep reading to learn more about it and what issues you might face.

Understanding underfloor heating systems

3D Illustration - Water underfloor heating in a house

Underfloor heating (UFH) systems operate on the principle of heat radiating from the floor up into the room to create a comfortable living or working environment. Such systems feature either electrical heating elements or water-filled pipes sitting within, or on top of, the floor structure. In operation, electric systems heat up through resistance, while in water-based systems, the warm water from a central heating system is pumped through the pipes. The floor then heats up and becomes a large radiant surface, warming the surrounding air and objects quickly and efficiently.

Types of underfloor heating systems

Electric underfloor heating:

  • Utilises electric heating cables or mats that are installed underneath the floor finish.
  • Each room can be controlled individually, which is ideal for zoning options and flexibility.
  • Thinner, easier to install in existing homes.
  • It can be more expensive to operate, particularly in larger areas where a water-based system is more cost-effective.

Water-based underfloor heating:

  • A network of water-filled pipes can be installed to connect each room, typically back to a boiler or heat pump.
  • Fantastic energy efficiency, mainly when installed with an energy source such as a heat pump.
  • Generates a consistent, gentle warmth, distributing the heat evenly across the floor surface.
  • Requires the installation of plastic (PEX/PE-RT) pipes or matting (our favourite product), a professional grade manifold, heat source and piping system to connect to your traditional heating system (or with a hot water heat pump, to become a radiator on the wall essentially) or with a hot water appliance and hydronic coils. Therefore, it is best suited for new builds or large-scale renovations.

Benefits of underfloor heating over traditional heating systems

  • Enhanced comfort: UFH eradicates cold spots and draughts, providing a consistent and comfortable internal environment.
  • Energy efficiency: By warming from the ground up, UFH requires lower operating temperatures that decrease energy consumption and cut utility bills.
  • Space-saving: With no requirement for unsightly radiators or ductwork, underfloor heating systems are hidden, maximising usable space and interior design possibilities.
  • Health and hygiene: No air movement and no circulation of dust particles means UFH promotes healthier indoor air quality and reduces the risk of allergens.
  • Design flexibility: Finally, UFH allows unfettered freedom and flexibility in room layout and furniture placement – nasty radiators impose no restrictions or awkwardly placed heating vents.

Installing underfloor heating in existing homes: Key differences

Collage with professionally installed floor heating system and fresh leveling

Assessment and preparation

Before installing any UFH system, evaluating the condition and type of existing flooring is crucial.

Different floor types of coverings may require different installation methods or adjustments to ensure the system's optimum performance. For example, carpeted areas may require additional insulation to prevent heat loss, whereas there may be additional preparation for installing solid surfaces like concrete.

It’s vital to understand whether UFH can be compatible with any existing heating systems, and this can also depend on whether they are wet or electrical.

Increased heating loads from UFH will mean it is essential to understand if boilers or heat pumps can support additional loads and to ensure they are set up to integrate correctly.

Equally, it is necessary to check the electrical infrastructure for electrical UFH systems to ensure they are compatible and do not overload the system.

Adaption and retrofitting

When retrofitting UFH into existing homes, there are several factors to consider. For example, the underfloor space is usually limited and inaccessible; installing UFH may also involve structural disruptions to older homes.

In these instances, innovative installation techniques, such as retrofitting the new UFH from above rather than below and using thin-profile heating elements that reduce the adjustment of floor height, can provide a solution.

When putting UFH down with different floor finishes, it is important to remember that different floor ranges have different heat conductive properties. UFH will work well with any well-specified floor, and good architects/workers can come up with a way to feed your UFH supply into the building.

UFH works well with various floor finishes – including stone, tile, wood, vinyl, and carpet – but it requires careful consideration of the heat conductivity and how it works with the UFH.

Design considerations

UFH system layouts must be carefully designed in homes with existing layouts to ensure heat is distributed evenly throughout the space. Zoning strategies can be employed to serve different heating needs in different areas of homes to maximise both comfort and energy efficiency.

With limited space, UFH installation can be challenging, as can working around obstacles such as furniture, fixtures or structural elements. However, there are ways to work around these restrictions to keep UFH installation in neat, straight lines, such as by relocating piping, using alternative heating methods in tight areas or arranging supply and return manifolds so that they’re located on the same side of tight spaces.

Compatibility and existing systems

Compatibility with existing heating systems is an absolute must for UFH to operate seamlessly alongside systems such as heat pumps or boilers. Retrofitting existing systems may require changes to piping configurations or replacing or adding heating manifolds to accommodate additional heating loads.

Integrating UFH with smart home technologies can add a new energy management and control level that can't be accomplished with typical programmable thermostats or home automation systems, allowing customised scheduling, remote operation, and control from smartphones and tablet devices.

Processes used in installing underfloor heating in existing homes

professionally installed hydronic floor heating system

A step-by-step installation process

All types of UFH systems consist of pipework or electrical heating elements laid beneath the floor surface. They also all share a common set of requirements at the installation stage. These include;

  • Site preparation & layout planning: Thorough site preparation is required before a UFH system can be installed. Carefully planning the layout of the UFH pipework or elements is essential for even heat distribution and ideal system performance.
  • Insulation layers: Insulation is a crucial factor in maximising the efficiency of underfloor heating systems. Insulation layers are laid beneath the heating elements to reduce downward heat losses and increase energy efficiency. Proper insulation can also help to keep running costs as low as possible and ensure the heat is spread evenly across the room space.
  • UFH pipes or mats laid out: Whichever type of UFH system is selected, the heating pipes or mats will be carefully laid out according to the predetermined layout plan. The aim is to give an even spacing, coverage, and uniform heat across the floor surface.
  • Pipes connected to the existing heating system or the installation of a new boiler/heat pump.

After the installation is complete, the UFH system is thoroughly tested to ensure that everything is in complete working order and that the system is operating as efficiently as possible.

The testing & commissioning stage includes;

  • For wet systems, pressure testing the system to ensure the pipework is fully sealed & identify any potential future leaks.
  • Electrical tests are carried out for electric systems to ensure that the system is working correctly & safely.
  • A thorough check is made to ensure there are no air locks in the UFH pipes.
  • Once testing is complete, the system is then ‘commissioned’ and adjusted as necessary to ensure it works as well as possible.

Comparison with new build installations

The process of installing wet underfloor heating in existing houses introduces several unique challenges compared to newly built installations. The first of these is accessibility to the underfloor spaces. Structural obstacles often restrict this, making innovative installation methods necessary.

Retrofitting from above and using thin-profile heating elements are currently the go-to solutions for this particular issue. Existing loads in the structure must also be evaluated and used to calculate load-bearing capacity. This will determine whether the inclusion of UFH can be accommodated, what amendments are to be made and how any changes will affect the system's performance.

How the UFH will be incorporated forms a significant part of a new build project, and the beauty here is the wealth of service options at the installer’s disposal and the more cost-effective nature of many of them.

One significant structural obstruction that must often be worked around is load-bearing walls, which impede them from being easily adjusted. One advantage a new build installer will carry over to one looking to retrofit a home is the existing infrastructure UFH must be fully or partially integrated with. Adapting an incoming heating supply is complicated, so it doesn’t spring an immediate remedy to an installer’s mind. Getting that supply to where it needs to go can then proceed in a way that is as unobtrusive as possible within the home.

Challenges in installing underfloor heating in existing homes

professional underfloor heating system in the room.

Structural limitations

Because they can vary so much in quality, the existing subfloor for underfloor heating in Victorian house can present many challenges when installing a UFH system. Uneven or damaged subfloors will require time-consuming and costly levelling or repairs to ensure the UFH system can be fitted correctly and prevent heat loss. And damp or wet subfloors can seriously damage UFH system components and lead to flooring failure above.

Access and space constraints

Accessing underfloor spaces in existing homes can be difficult, particularly in multi-story buildings or houses with finished basements where the location of underfloor HVAC systems will often require snaking the distribution system ductwork and/or hydronic piping through somewhat restricted spaces in between subfloor panels or within existing ceiling or floor assemblies.

This necessitates careful planning and/or the use of specialised installation techniques and/or equipment to properly navigate tight spaces and any obstacles, such as wiring, plumbing and/or ductwork, which may be present beneath the subfloor panels or between ceiling joists.

Integration with existing infrastructure

Integrating UFH with older heating systems such as boilers or radiators may present compatibility problems or require upgrading or modifying existing systems to handle the additional heating load. This can add complexity and cost to an installation.

Some existing homes may not have electrical systems capable of safely and efficiently managing the increased power demand of electric UFH, necessitating a complete system rewire or the installation of dedicated circuits. The additional cost of these measures should be factored in.

Final thoughts

In conclusion, installing underfloor heating in an existing home poses distinctive challenges but promises unbeatable comfort and energy efficiency benefits. By understanding how installation processes differ from new constructions, addressing challenges such as structural limitations, integration of the system within the existing infrastructure, and balancing costs, homeowners can make an educated decision to enhance their living space.

At Next Level, we specialise in underfloor heating installation services, providing custom solutions that maximise home comfort year-round. Get in touch today to learn more about our expert underfloor heating services and how Next Level can elevate home comfort to the next level.

Next Level Brand - Professional Installation of Underfloor Heating Systems: Image representing the Next Level brand, showcasing professional installation of underfloor heating systems under concrete screed.

Send Us a Message

Get Your Free Survey And Quote

Contact Us →