Best Position for Radiators

[benben5555]

Traditionally radiators were often positioned under a window. With a view on maximum heat retention in a well insulated house is this the best approach? My simple logic says to site the radiator away from the window so as to not lose heat as soon as it is produced.

 

Has anyone got any thoughts or experience on this?

 

Thanks!

[JohnMo]

Never seen why radiators were under windows, all the heat got trapped behind the curtains and not in the room.

 

When we renovated our last house I put all the radiators on the walls the other side of the room from the window.  It work well.  But maybe best to plan it around the furniture, if that's an option

[markc]

I’ve never understood why radiators were under windows, one idea was that a window is a less likely place to put a piece of furniture.

[jayc89]

One heating engineer we spoke with recommended to install new radiators on the wall to the side of a room's door as that space is used to get in/out of a room it's unlikely to ever be blocked by furniture etc.

[Marvin]

3 hours ago, benben5555 said:

My simple logic says to site the radiator away from the window so as to not lose heat as soon as it is produced.

My simple logic always said that the cold would come from the window so I put the radiator under the window, the theory being that the cold air didn't have to travel across the room to warm up. I think I had the idea after standing in a room in front of an open fire with my face hot and my butt cold.

[Ferdinand]

In a well insulated house I put them on internal walls as the cold air movements near windows should be less, and it makes running the services much easier.

[wozza]

15 hours ago, markc said:

I’ve never understood why radiators were under windows, one idea was that a window is a less likely place to put a piece of furniture.

 

12 hours ago, Ferdinand said:

In a well insulated house I put them on internal walls as the cold air movements near windows should be less, and it makes running the services much easier.

 

Radiators were typically placed under windows as single glazed windows were the coldest part of the room and the cold air from the window would help the warm air from the rad to circulate around the room better.

 

[MikeGrahamT21]

Window will still be the coldest part, even in the best house. From what I’ve learnt, the effect of cooler air pushing down and hot air rising, causes the mixture of both to push into the room rather than just rising up, going along the ceiling and dropping as it cools, which should result in higher levels of comfort in theory

[Dudda]

Radiators don't actually radiate much heat. Most of the heat is from convention where the air moves around the room. Radiators were traditionally placed under windows to heat the cold air and create convection currents. This warmed air would travel up across the ceiling down the opposite wall and back to the radiator heating the whole room. If you were to put the radiator on the wall opposite a single glazed window then the window would cool the dropping air and a cold flow of air would travel along the room at the level of the occupants where they'd feel a cold draft even if the room was warm. There was sense and logic to it.

 

The position isn't as important now with very high performance windows. Instead consider the layout of the room and position them where air can move infront of them. They shouldn't be placed near the head of a bed as they convection currents can cause a flow of air around the head. Again not as much of an issue in a modern well insulated house. The only place you need to give real consideration to them in a modern house is double height areas as the warm air obviously rises more. Particularly if you've a mezzanine overlooking as this will be the warmest part.

[SteamyTea]

Put the radiators in a well insulated floor.

Can call it underfloor heating.

[Gordo]

Very basic heating engineer question this. The convection currents mean cold air falls and warm air rises. Therefore if you put radiators below windows this heats the cold air at window it rises to ceiling, travels along ceiling to far wall and falls as it cools, then travels along floor towards window wall and cycle continues.

 

window walls are always the coldest by quite a margin. So always best to place radiators under windows. If you place on far wall the drafts at floor level will be colder. Second choice is a flanking wall

Edited October 27, 2021 by Gordo

[Marvin]

On 25/10/2021 at 23:48, Marvin said:

My simple logic always said that the cold would come from the window so I put the radiator under the window, the theory being that the cold air didn't have to travel across the room to warm up. I think I had the idea after standing in a room in front of an open fire with my face hot and my butt cold.

As I commented.....