Radiators under windows.

It depends! ?


The old theory, with sliding sash windows, was that you open them a little so that fresh cold air drops over the radiator (i.e. convector) is heated up and provides a pleasant warm temperature. The stale warm air which has risen to the top of the room exits via the top opening.


That was before we tried to conserve heat.


In practical terms, if you need to put furniture against the other walls, the space under the windows may be all that is available.


What you shouldn't do is cover the radiators with floor-length curtains. Unfortunately that is exactly what Mrs P likes and then she complains about the cold. ??

It depends on ones priorities.

For optimum comfort and minimising draughts and condensation, then yes radiators should be placed under windows.

For minimum fuel use and therefore minimum running costs, then radiators should be on inner walls and away from windows. Placement under a window implies an outside wall, with heat losses through the wall and through the window.

If heat sources are on inner walls, then any losses are only into other rooms rather than to the outside.

Sparkingchip:
Lets be more specific.

Should electric radiators be installed under windows?

Andy Betteridge 

Yes if optimum comfort is the design priority.

No if fuel economy is the design priority.

I am always surprised how much radiation there is from my radiators.


They actually do both, but I have no idea what proportion of each


David

So what about the potential risks from an electric heater being covered with long curtains?


Andy Betteridge

covered with log curtains


I think you're barking up the wrong tree there Andy!


Regards


BAD

Long curtains. Log curtains would only add fuel to the fire ?

For those that are wondering this analysis of radiation from a panel radiators,ompared to the makers rating  suggests about 20-25% of the heat from a domestic rad is actually radiated ( In the stefan-bolzman 4th power of absolute temperature way) from one surface, and the rest is presumably a mix of what is convected and the radiation off the back heating the wall to some temperature between that of the room and the hot water. Not negligible, but certainly not the dominant effect.