A convector or a radiator under the window
Both devices give the room the heat of the water from the circuit, and by an ordinary window a resident won’t feel the difference. It appears in three places: whether there is somewhere to put the unit, what happens to the output at a low supply, and whether the floor can still be touched.
Where they really differ
| Criterion | In-floor convector | Radiator |
|---|---|---|
| Floor-to-ceiling glazing | The casing lies in the screed under the glass, grille on top | There is no wall under the glass, nowhere to hang it |
| Appearance | Only the grille is visible | The device is on the wall |
| Installation | Set into the screed at the design stage | Hung at any time |
| Cold from the glass | A curtain along the glass, if the length is close to its width | Heats where it hangs |
| Finished floor | Too late: the screed can’t be redone | Can be installed |
| Low supply, 45/35 | Output without a fan drops threefold | Also drops: the physics is the same |
When a radiator is the right choice
An ordinary window with a sill, the renovation is done, nobody is going to raise the floor, the pipes are easily run to the wall. In this case a radiator does the same job more simply, and we won’t talk you into an in-floor convector. There’s also an argument in its favour: a radiator gives off part of its heat as radiation, and this is felt when a person sits nearby for a long time.
Floor-to-ceiling glass, but the screed is already poured
A radiator is not the only option here. Carrera has a floor-standing FRH that is placed right in front of the glass, and a skirting BR along the wall. The principle is the same, a curtain along the glass, but the floor doesn’t need to be opened up.
| Device | Width × height, mm | W per 1000 mm, 45/35 |
|---|---|---|
| M/C 65, in the screed | 230 × 65 | 82 |
| S/C 90, in the screed | 230 × 90 | 101 |
| FRH, on the floor | 148 × 175 | 123 |
| FR2H, on the floor | 290 × 175 | 169 |
| BR 18, skirting | 60 × 180 | 77 |
| BR 21, skirting | 60 × 210 | 97 |
All of this is natural convection. One mode is taken, 45/35, because in our tables in-floor units are given for 85/75 and 65/55, while floor-standing and skirting ones for 90/70 and 70/50: the “per metre” catalogue figures can’t be placed side by side. At 45/35 the spread is 77–169 W, so the type is chosen by location and appearance, and the output is matched by length.
Where people go wrong and when a convector is not suitable
- A catalogue figure instead of the mode. S/C 90, 2000 mm long, without a fan gives 770 W at 85/75, 513 W at 65/55 and 256 W at 45/35. A heat pump usually runs at 45/35, so the 45/35 row is taken for it: a version with a fan (SV 90 at 30% speed gives 569 W here) or a longer unit. A radiator isn’t saved from this arithmetic either; in more detail in the review of a convector on a heat pump.
- A decision after the screed is poured. A casing can’t be laid in a finished floor: what remains is FRH, BR or a radiator.
- A thin screed. The lowest casing is 65 mm. If the depth is less, there is no in-floor series for you.
- Heating is turned on infrequently. For an office or a shop, what matters is the speed of reaching the mode, not the sill; this is a separate review for an irregular schedule.
What to check before deciding
- What is under the glass: a pier or the floor. Measure the height from the floor to the bottom of the glass.
- The screed: poured or not, and what depth exactly under the glass, not in the middle of the room.
- Supply and return in writing for the coldest day: 85/75, 65/55 or 45/35.
- The output is taken from the row for your mode, not from the top catalogue figure.
- For a version with a fan: a 24 V line and space for the power supply and thermostat.
- The order of magnitude is given by the output calculator; the final selection is confirmed by an engineer.
Can a radiator be placed under a panoramic window?
Yes, if there is a pier under the glass: the radiator is hung on it. When the glass goes to the floor, there is no pier, and what remains is a convector in the screed or FRH or BR in front of the glass.
Is an in-floor convector needed if the heating is on a heat pump?
What’s needed is not a specific device but the table row for 45/35. S/C 90 at 2000 mm without a fan gives 256 W there versus 770 W at 85/75, so for a heat pump a version with a fan or extra length is taken.
Can a convector be added to a finished renovation?
An in-floor one, no: it needs a screed. FRH and BR are placed on a finished covering, which won’t have to be opened up.
Does a convector make noise compared with a radiator?
Natural convection is silent. A fan makes noise: SV 90 at 30% speed gives 19.8–24.3 dB, at 100% up to 46.0 dB (range by lengths 1000–3000 mm).