A curtain in front of a radiator: mistake or not?
A curtain should not cover a radiator or obstruct the way it spreads heat. To choose the length, respect the clearances stated in the appliance’s instructions, with the curtain open as well as closed.
The fitting has to meet two needs: covering the window to improve comfort and keeping the heating clear. Turning the thermostat down at night does not make a curtain that covers the appliance acceptable.
What really happens behind the curtain
Fabric placed in front of a radiator can obstruct the circulation of warm air and its spread through the room. The set-up depends on the appliance, the window and the curtain: there is no single distance that applies to every model.
As ADEME recommends, keep radiators clear. The manufacturer’s instructions specify the clearances to respect around your appliance.
Four configurations to consider
| Configuration | Effect |
|---|---|
| Long curtain, pressed in front of the radiator, closed | Avoid: the fabric covers the appliance and obstructs heat distribution. |
| Long curtain, held a few centimetres off the radiator | A few centimetres do not guarantee a compliant installation. Check the clearances in the instructions. |
| Curtain stopping at the sill, above the radiator | Only possible if the length and position respect the clearances prescribed for the appliance. |
| Long curtain, but radiator placed elsewhere or room with no radiator under the window | The length can cover the window down to the floor if it obstructs neither an appliance, nor ventilation, nor a walkway. |
How to choose the length
If there is a radiator under the window, note its position and read its instructions before ordering the curtain. Work out the length that keeps the appliance clear, even once the panel is closed. With no radiator under the opening, adapt the drop to the floor and to how people move around the room.
Both lengths are covered in detail in should curtains touch the floor, and the hanging height in how high to hang a rod.
What the curtain brings when it is well fitted
A thermal curtain provides additional protection in front of the window. It does not replace maintaining the seals, repairing the window frame or proper insulation.
| Type of curtain | Weight | Effect in winter |
|---|---|---|
| Kurtens linen-effect sheer | 265 g/m² | Fabric weight is not enough to establish thermal performance. |
| Plain blackout | 315 g/m² | Blocking light does not, on its own, prove thermal performance. |
| Thermal blackout, three layers | 620 g/m² | Kurtens 3-in-1 curtain: up to 7 °C, measured in the laboratory. Results in use depend on the window and the fitting. |
Is it bad to put curtains in front of a radiator?
Yes, if they cover the radiator or encroach on the clearances given in its instructions. The fabric can then obstruct the circulation of warm air and its spread through the room: the heating runs, but part of its heat can stay behind the curtain. Keep the appliance clear, with the curtains open as well as closed.
The problem lies in where the curtain hangs, not in the curtain itself. In the instructions, look for the guidance on curtains and on the space to leave free around the appliance. With an electric heater, safety is at stake too: it is covered below.
Can you hang a curtain above a radiator?
Yes, provided the curtain stays outside the clearances prescribed by the radiator’s instructions, open as well as closed. Stopping above the appliance is not enough on its own: the bottom of the curtain must stay far enough from the radiator never to cover it or hinder the warm air rising into the room.
First find, in the instructions, the limit the bottom of the curtain must not cross. Then set the height to order from that limit, taking into account the heading you choose (eyelets, pencil pleat tape or rod pocket), which changes where the curtain sits in relation to the rod.
A short curtain can be ordered to your dimensions in the configurator, including under 150 cm high, as long as the size stays within the dimensions it accepts. Beyond that, customer service takes over.
Can you have floor-length curtains with a radiator under the window?
Only if, once closed, they leave the radiator clear and respect the clearances in its instructions. When the radiator sits right under the window, a closed long curtain generally hangs in front of it. In that case, choose a curtain that stops above the appliance instead, or another arrangement compatible with the heating.
Check the curtain’s whole travel: the fabric and its folds must stay outside the prescribed clearances while opening and closing, not only once the curtain is drawn to the side. A gap of a few centimetres does not guarantee this, as the table of configurations points out.
Can you put curtains in front of an electric heater?
Not if they cover it, touch it or encroach on the clearances prescribed in its instructions. Fabric lying on an electric heater, panel or convector, or pressed against it, can make it overheat. Check that the curtain stays outside these clearances, open as well as closed: it is a matter of safety, not just comfort.
Before ordering, note from the instructions the clearances and air openings to keep free, especially above the appliance, where the warm air often comes out. Never cover the appliance with a curtain, even if it carries no warning.
Frequently asked questions
Do you need a shorter curtain if there is a radiator?
A shorter length can work, provided you follow the appliance’s instructions. A panel that stops at the sill is not automatically far enough from the radiator: measure the actual set-up.
Can you keep a long curtain with a radiator underneath?
Only if the installation keeps the radiator clear, including when the curtain is closed. If that is not possible, adapt the length or the arrangement; turning the heating down at night is not enough.
Does a reflector behind the radiator replace a curtain?
No, they do not do the same job. Whether a reflector is worthwhile depends notably on the wall and the appliance. Check its compatibility and the manufacturer’s advice before installing it.
Does a curtain closed at night block the heating?
It can obstruct the heating if it covers the radiator or reduces the necessary clearances. Check the panel’s closed position before using it at night.
The rest of the season is gathered on our winter curtains page, and our made-to-measure thermal curtains are made to the dimensions you enter, at a height compatible with your radiator’s clearances.
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