Why are radiators double sided?

Why are radiators double sided?

John - I think there are two sides to this. One is, making sure that the radiator works well to heat the room. The other is the manufacturing element, which is making sure that the radiator is cheap to fabricate. Radiators, it's a bit of a strange name, because I think the perception is that they transfer most of their energy through radiating. Most of the energy transfer from radiation actually comes from convection. By that I mean the radiator heats up the air that's next to it, then that air circulates around the room, so it rises up to the ceiling and then circulates back round to the other side of the room. In that sense, the most important thing that your radiator is doing is heating the surrounding air. So what you want is a radiator design that essentially maximises the surface area, the contact area, between the hot parts of the radiator and the air. So really, as long as your radiator is heating the air locally, it doesn't really matter how it's designed. It's important that the air can get round the radiator.

Will - I suppose I was concerned if there was a radiator pumping heat out of the back towards the wall, it would be cooking my wallpaper, but I feel like it's being sucked towards the colder parts of the room far more quickly before it could do any real damage.

John - That's right. And it's not ever that hot either, right? I think water in central heating systems is about 60 degrees? Something like that. I think the other reason that you see a symmetrical design is that, well, one, if you've got a good surface area contact, you may as well use it on the front as, as the back. And the other is that if you've got a machine stamp that's stamping your radiator panels out of a flat piece of sheet metal, then you may as well use the same template for doing the front and the back. That makes it much cheaper to produce.

Will - Who knew that physics and interior decoration had so much to discuss?