From Scandinavia comes a completely different way of looking at underfloor heating. System that drastically reduces installation costs. That doesn’t require the usual expensive and time-consuming process of pouring concrete. That doesn’t halt work for two or more weeks for concrete to settle and dry.
We’re now presenting an underfloor heating system that can literally be put down in hours, easily, so saving on labour cost whilst other vital construction work continues unhindered and on-schedule.

In a series of computational simulations performed by the Division of Building Technology, Royal Institute of Technology (KTH), which were presented during a seminar at Nordbygg­mässan 1996 (the largest building exhibition in Scandinavia), the thermal performance of various underfloor heating systems were demonstrated. Specifically, the thermal inertia of the systems was highlighted.

As boundary condition, the temperature of the water in the pipe was increased by 1 °C in one step. The thermal response was studied by observing how long time it took for the increase in heat dissipation, due to the increase in temp­erature, to fully be transmitted through the top surface of the floor construction.
This con­struction was assumed to be a slab on ground with the thickness of concrete corresponding to 150 mm and 150 mm of thermal insulation underneath. The pipe spacing was 300 mm. Ceramic tiles (8 mm) were used as flooring, ­set with 4 mm of tile adhesive.

In simulations of the underfloor heating systems with embedded pipes, the pipes were situated so that there was;
1. 110 mm of concrete above the pipes;
2. 55 mm of concrete above the pipes;
3. 30 mm of concrete above the pipes.

In the fourth simulation, an installation of a ­surface-mounted system resembling Flooréwa, but with the pipe spacing 300 mm and aluminium foil thickness of 0.5 mm, was modelled.

A method of describing thermal inertia is with the so-called time constant, which in is a quantification of the time it took for the construction to adapt to the change in temperature. In this case, the time constant is defined as the time it took for 63 % of the process to occur, until all heat has penetrated through the flooring sur­face. Results are shown below.

Conclusions

• A pipe close to the surface will more effectively transmit heat (more upward power per degree Celsius). The concrete will, for pipes embedded deep in the construction, give rise to a thermal resistance between the pipe and surface, even though it has good thermal conductivity.
• Due to the heat capacity of the concrete, the thermal inertia of the construction is large. Time lapses while heat is emitted trough the masses of concrete. In the case “Embedded 110 mm”, no heat leaves the surface until one hour has passed.
• Surface-mounted systems react quicker to meet heating requirements with lower water temperatures than the embedded systems. What is not revealed in the case “Embedded 30 mm” is that the surface temperature is quite non-isothermal: a foot can detect were the pipe is situated. The knee in the figure labelled “EPS and al-foil” is due to that heat is conducted to the flooring surface during the initial stages of the process. Thereafter, the concrete slab beneath the system will successively be heated and as this occurs, more heat will be conducted upwards.

Flooring materials
CERAMIC TILES – Dry spaces
In dry spaces, ceramic tiles can be installed directly on Flooréwa- or EASY-panels. Two types of tile adhesives have been used in this way, which through experience (since 1991) and test have shown to have the following characteristics:

• Good attachment onto aluminium, so that the surfaces do not need a layer of primer
• Slightly flexible which allows small movements in for intermediate floors with wood beams.

These two products are Mapei Granirapid and two component Mapei Kerabond & Isolastic.

WET ROOMS
In wet rooms, the panels must first be primed and screeded before applying wet-proofing membranes. Alternative methods are possible, for example advanced membranes such as Mapei’s Mapelastic.

WOOD FLOORING
Parquet, laminate and floor boards are commonly laid floating with two intermediate layers, usually paper felt on top of a 0.2 mm thick PE-foil. Noise reduction layer may be optional, but usually hinders heat flow from the UFH.