Radiant systems types

Depending on the application or the surface concerned, we can identify 3 families of radiant systems:

If instead we consider the UNI and ISO standards currently in force in radiant systems sector (UNI EN 1264, UNI EN 15377, ISO 11855), then there are basically 2 types of radiant systems:

1) Embedded radiant systems (embedded: incorporated, laid inside, drowned)

Pipes are completely embedded or below the inertial mass. Inertial mass means the layer (also prefabricated) to which is entrusted the task of absorbing and transmitting the energy, conveyed by water circulating in pipes, to rooms to be air conditioned.

2) Free hanging radiant systems (free hanging: suspended)
These are generally prefabricated panels with low thermal inertia (inertial mass reduced to a minimum), where pipes with reduced diameter are embedded in a panel (plasterboard, fiberglass, etc ...) or incorporated in a diffuser element (metal), which have on the non-visible surface an insulating layer (polystyrene, polyester, etc ...).
These prefabricated panels are fixed to the wall or ceiling with the help of a metal structure or a frame of wooden slats. In most cases, these systems offer an empty space behind them.

Are so-called modular systems for raised or floating floors also part of this category? These are panels with low thermal inertia, raised above floor thanks to a metal structure, with an empty space behind them and with an insulating layer on the non-visible face: it follows that, by analogy, these panels should also be considered among the free hanging radiant systems.

EMBEDDED RADIANT SYSTEMS (or incorporated).

In turn, they are characterized by UNI and ISO standards (UNI EN 1264, UNI EN 15377, ISO 11855) in various types: 

1) floor covering
2) inertial layer (cement screed, anhydrite screed, asphalt screed, prefabricated layer)
3) pipe or ducted plate
4) protective layer
5) insulating layer
6) structural base
7) conducting device
8) separating layer
9) levelling layer

TYPE A : Systems with pipes integrated into the screed. These are the best known and most used systems for underfloor heating and cooling. 
TYPE B : Systems with pipes under the screed / prefabricated layer. This type mainly includes the so-called dry radiant systems, in which the insulating layer is usually equipped with special housing grooves for the pipes and these are wrapped (for most of their development) in special thermal diffusion elements, mostly made with metal sheets. The inertial layer, laid over the insulating layer, can coincide with a cement screed or usually a layer of prefabricated elements laid dry (gypsum fiber, eraclit, metal plates, etc.).

TYPE C : These are systems similar to type A, with the difference that the screed is divided into two distinct layers and separated by a decoupling sheet (polyethylene sheet, nylon, etc ...). The deepest layer is the one in which the pipes of the radiant system are incorporated, while the surface layer acts as a support for the final floor. In fact, type C radiant systems are used when it is planned to build an "on-site floor" on a concrete bed: "Venetian floor" (small pieces of marble or stone), "Palladian floor" (marble or stone slabs), "Stone cubes floor" (see image above). It is clear that it is impossible to combine the two laying phases (laying the radiant screed and laying the floor on a layer of bedding cement) and therefore it is preferable to adopt a clear separation between the two layers to allow for any differences in thermal expansion.

TYPE D : Systems in which the pipes are replaced by planar elements, in whose section the passages for water are obtained. These planar elements are connected in series or in parallel, for the formation of the circuits of the radiant system. The inertial layer can coincide with a cement screed or with a layer of prefabricated dry laid elements (gypsum fiber, eraclit, metal plates, etc ...).

Finally, there are 3 other types of embedded (or integrated) radiant systems identified by current standards (in particular ISO 11855 standards): Type E, Type F and Type G.

TYPE E : The pipes of the radiant system are not incorporated in a surface layer of the structure concerned (floor, wall or ceiling), but close to the central axis of the structural element itself (horizontal or vertical). It is therefore not necessary for these systems to adopt an insulating layer, because the intent is to radiate energy towards both sides of the structure. For more information on these systems, see the specific data card: TABS systems (thermally active building systems).

TYPE F : These are systems that provide for the use of "capillary pipes" (diameter ≤ 10 mm), suitable for being embedded in a surface layer of plaster. It is clear that the possible applications are for wall or ceiling radiant systems (on the floor, such a thin layer would lead to poor compressive strength) and that the goal is to reduce the thermal inertia of the system as much as possible (time to reach the steady state surface temperature).

1) finished floor

2) substrate

3) thermal diffusion device

4) pipe

5) structural beam

6) suspended ceiling

7) insulating layer with reflective surface

TYPE G : These are radiant systems designed for application in wooden constructions: prefabricated houses or similar, with wooden structure floors. There are two versions, based on the laying surface of the pipes: in version 1 the pipes are "embedded" in the substrate above which the final floor is laid; in version 2 the pipes are applied to the soffits of the substrate (laying from the lower floor). In both cases the pipes are wrapped in special metal thermal diffusion devices for most of their development.

SYNTHESIS

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