Thermal output of radiant systems

After having explained how radiant systems work in the previous

part and having mentioned the small convective air movement

that this type of system generates, here we discuss the thermal

output that the Standard takes into account.

Heating

Underfloor system

10.8 Watts per m2 for each °C of difference between the ambient

and surface temperatures of the system

Wall system

8.0 Watts per m2 for each °C of difference between the ambient

and surface temperatures of the system

Ceiling system

6.5 Watts per m2 for each °C of difference between the ambient

and surface temperatures of the system

Cooling

Underfloor system

6.5 Watts per m2 for each °C of difference between the ambient

and surface temperatures of the system

Wall system

8.0 Watts per m2 for each °C of difference between the ambient

and surface temperatures of the system

Ceiling system

10.8 Watts per m2 for each °C of difference between the ambient

and surface temperatures of the system

As you can see, the three systems, floor, wall and ceiling, differ

in terms of performance because of the action of the above-

mentioned convective air movements. This results in different

characteristics that make them suitable for different types of

systems. For example, it is clear that the ceiling system is the

ideal solution for cooling systems.

Beyond these characteristics, without going into details, one

should consider that the average temperature of the water cir-

culating in the system is about 5 °C lower than the surface tem-

perature in the underfloor system and about 3 °C lower in the

wall and ceiling system.

For a better understanding, here is an example:

To provide 35 W/m2 in

cooling

underfloor system

wall system

ceiling system

Surface temp.

20.7°C

21.6°C

22.8°C

Average Water Temp.

15.7°C

18.8°C

19.8°C

In this case, the ceiling system is by far the most efficient sys-

tem, with a surface temperature far from the dew point and an

output 4 °C higher than the underfloor system.

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Underfloor Radiant Systems - Product Guide

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