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Underfloor Heating; Heating takes to the floor

Space-saving and energy-efficient, underfloor heating systems are gaining popularity across all market sectors. Specifying this type of heating solution can make a significant contribution to a building's energy efficiency rating - so it is well worth considering. Peter Binstead, technical director at Ferroli, looks at the growth in underfloor heating and the key points to consider when installing this type of system in solid, suspended and floating floors
Underfloor Heating; Heating takes to the floor
WITH its economic and ergonomic advantages, an increasing number of commercial building developers are now considering underfloor heating when they embark on a new build or renovation project, from hospitals and schools to offices and retail premises.

Because they are embedded in the fabric of a building, these systems are best installed in new build projects, or at the very least as part of a major refurbishment.

So what are the benefits? Well, the fact that there are no radiators means more space and flexibility when it comes to interior layout.

There are also savings in the boiler specification, plus a reduction in running costs of up to 30%.

Underfloor systems work using radiant heat rather than convection, so the warmth is evenly spread through the room with no cold spots. This radiant heat is achieved by water circulating at a much lower temperature than normally required by radiators.

Typically, underfloor water circulates at 200C - 240C, rather than 600C - 800C for radiator water. Thus, less heat input is required to maintain a comfortable temperature. As a result, a smaller, less costly boiler can be specified without compromising thermal comfort.

Last but not least, employees benefit from a comfortable working environment that is also healthier, with none of the germs, fumes or allergens that can be distributed around the building when using air which is circulated around the room by convection-effect radiators.

Although electric underfloor heating systems are available they are generally more expensive to run than wet systems and suited to small areas such as bathrooms.

Wet systems work particularly well with a condensing boiler because the low return temperature means the boiler operates at its optimum performance, resulting in greater energy efficiency.

Where can you install?

Once installed, an underfloor heating system is not easily modified or removed, so it is essential to appoint a contractor with the necessary skill and experience to ensure you get it right first time. Because it is incorporated into the very structure of the building, the installer should understand all the elements with which the system has to integrate, such as boilers, pumps and manifold, and the system must be designed and installed to satisfy current Building Regulations.

One of the advantages of underfloor heating systems is that there are no visible components in the room. A network of specially-manufactured, high-performance, cross-linked polyethylene (PEX) or polybutylene (PEB) pipe is incorporated in one of a number of supporting systems. In most commercial buildings the warm water pipe system is cast into the solid concrete floor. However, there are also solutions that can be built into a suspended timber-joisted floor or floating floor system.

Solid floors

Underfloor heating is ideal for solid floor constructions where the warm pipe works with the concrete floor with a high thermal mass that will release heat slowly. The system's heating pipes are embedded in the structural concrete or screeded concrete overlay. A typical solid floor is made with concrete over a damp-proof membrane, followed by a layer of insulation. The underfloor heating pipes are laid on top of the insulation. Another layer of concrete or pourable screed is then applied to cover the pipes and the floor is finished with tiles, slates or stone, for example. A manifold connects the heating appliance to the underfloor pipes and controls the flow of warm water into different pipe circuits or zones as required.

Suspended floors

Underfloor heating can also be specified with most suspended floors, including conventional joisted floors and batten systems mounted on solid floors. If considering this type of heating it really needs to be planned during the early stages of a project to ensure a suitable floor construction is used. Also, where timber is part of the floor it is essential that the timber is totally dry or it may shrink or crack with the heat.

The surface timber should not rise above 300C or the timber may distort, and a gap should be left around the edge of the timber to allow for expansion. Ferroli's system for these applications is simply laid on top of the floor and the heating pipes slotted into place - it is then ready for the chosen floor covering to be fitted.

Floating floors

These floors are very popular because they reduce the overall loading within the building and have good acoustic properties.

Ferroli's underfloor heating system for floating floors, for example, is based around insulation panels that are pre-grooved at 200mm centres to accept the heating pipes. The grooves are designed so that an aluminium heat diffuser plate can be installed before the pipe to transfer the heat upwards into the room.

When you consider the benefits for developers, property owners and end users, demand for underfloor heating systems certainly looks likely to grow. In the continuing quest for greener buildings, this energy efficient heating option is ideally placed to help designers and specifiers satisfy the increasingly stringent U-value standards for commercial buildings.

Ferroli: or T: 08707 282882
1 May 2007


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