Reflective foils for radiators are thin insulating panels that are usually coated with aluminum on one side. This should reflect the heat radiated to the rear back into the room instead of being lost via poorly insulated outer walls (as is often the case in old buildings). However, the question arises as to how effective the attachment really is. And do reflective films possibly pose certain risks? We’ll tell you.

Basically, the thicker a radiator reflective foil is, the better the insulation should be – but of course the price also increases with increasing thickness. Depending on the manufacturer, this often starts at three millimeters, but there are also insulation mats that are between four millimeters and six millimeters or even up to 25 millimeters thick. And that’s not the only difference: reflective foils can either be fixed to the wall with adhesive tape (or e.g. a mounting adhesive) or they are self-adhesive. But we come to the crucial question of how sensible it really is to attach an insulating mat behind the radiator?

The good news is: insulating mats have an insulating effect and should therefore be able to reduce heating costs. The bad news is: According to experts, the savings are just between 1.5 and 4 percent. And that only if there is poor external insulation (i.e. in old buildings). As a result, heat is lost via the facade. This means: In modern new buildings, no noticeable change in the energy cost billing is to be expected from the attachment of a reflective film. The montage can therefore be useful, but only produces a minimal effect.

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Normally, reflective tapes are supplied in rolls, regardless of whether they are self-adhesive or not. However, thin insulation mats can also be folded – that depends on the respective thickness and the manufacturer. But back to installation: In order for the film to achieve its full effect, you must ensure that the aluminum-coated side always faces the radiator – this is the only way the heat can be reflected back into the room. You should also pay attention to the following points:

And another tip: Always attach the reflective foil with two people, which makes the installation much easier – one person holds the insulation mat and the other smooths the foil down to eliminate all air bubbles. In this way, the film does not slip during installation.

If the reflective foil is improperly attached behind a radiator, moisture can form between the wall and the insulation – and thus promote mold. To avoid this, you can take preventive measures during installation: For example, if the panels are self-adhesive, you should always make sure that there are no gaps between the wall and the foil. An ordinary paint roller (preferably with a telescopic rod) can help to press the film down evenly. Insulation panels, on the other hand, which are not glued on, should always have a flush connection to the wall. If you cannot attach the reflective foil flush, it is definitely helpful to dismantle the radiator beforehand. Although this involves more effort, it ensures a seamless result.

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