DIY Doctor UK DIY Forums

Seem to remember in the past being told that radiators should be fitted under windows. Is this correct please? Currently have two radiators fitted under windows against external wall of living room but for all sorts of other reasons including pipework access they would be better elsewhere. Would this be a problem from a heating point of view?

I too have been told to put radiators under the window - the reason is minimisation of draughts. Windows are cold and the air hitting them sinks, however the heat from a radiator under the window counteracts this.

Imagine a room with a window, and a rad on the opposite wall. The warm air from the rad rises, travels across the ceiling to the window, where it cools, and sinks to the floor and across the floor back to the rad position, causing air to circulate around the room and a horrible cold draught around your feet.

Placing rads on sidewalls causes similar (but less severe) problems. If you have to go with a side wall. I would put the rad as close to the window as possible to minimise the effect.

Radiators are fitted under windows so that the cool air is heated and wont cause a draught or chill.

But these day with double glazing etc draughts are minimal so I fit the radiators wherever the customer wants it. Sometimes to fit in with decor and furniture, and sometimes for neatness and the easiest way to run the pipes.

Double glazed windows, in theory, should eliminate the need for a radiator on the external wall.....so i read somewhere. yet i do not agree. In an ideal world i would say external wall everytime im afraid.

The name radiator means to radiate so heat should be provided at the coldest point to heat the coldest point with the excess heat radiating into the room. The room isnt going to get cold because of an internal wall but it will if the external wall is cold.

To be precise - radiators do not radiate heat, the process of heat coming from heat emitters and heating the internal air is through convection. Convection currents, where the warm air rises travels and then falls when cooled.

So radiators should actually be called and are sometimes heat emitters.

I don't agree that radiators should have to be on external walls, maybe before we had cavity wall insulation.

All things being equal they are better underneath windows for the reasons earlier posters have mentioned. Even double-glazed windows are usually the coldest points in the room and downward circulation from them in winter creates draughts.

If you don't like this for cosmetic or plumbing reasons then put them anywhere you like - it will be OK - but there will likely be increased air circulation as a result.