Why are radiators placed under windows

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One question that is often asked when it comes to radiator placement is why radiators are placed under windows and whether it is possible to locate radiators in other areas of a room. In the past, radiators have often been located under the window in a room because this is the coldest area in the room. Historically, older windows would be single glazed, and this type of window used to let a lot of cold air into the room. This is one of the reasons the radiator was placed in this location as it would then help counteract the cold air and draft.

In a room with single glazing, the reason it is more efficient to place the radiator under the window is due to conduction. On a traditional radiator most of the heat that comes from the radiator is emitted as hot air through the top of the radiator. This interacts with the cold air from the window, and this cold air then helps push the hot air from the radiator into the room.

This in turn keeps the room warmer than it would be if the radiator was in a different location. Today, many homes, especially new builds will have double glazed or even tripled glazed windows which makes these windows exceptionally efficient. Since these windows tend not to leak as much heat and introduce less cold air into the home then there is more flexibility in the placement of the radiator in the room.

However, even though with modern glazing helping the placement of a radiator become more flexible, many people still opt to put a radiator under the window simply because it is a space within the house where furniture is not often placed, so it makes a great spot for the radiator. One of the reasons for this is that the efficiency of the radiator is greatly reduced if it is blocked by furniture. That is why it is never recommended to place sofas and large objects directly in front of the radiator.

In these situations where furniture is blocking a radiator then the object will benefit from the heat mostly, and not the room itself. For those who want more control over their interior design then there are a lot of flexible options available here at Mr Central Heating available for those homes fitted with modern windows.

Reason is quite simple. If you have a window without radiator and outside is really cold, the window glass would be cold as well.

This will lower temperature of the air around the window and this air will flow immediately down physics. So if someone want well heated room with very cold floor.. That's why it is wise to put radiator under the window. Because under window is the place where delta-T the Change in Temperature is largest in the whole room.

What is an efficiency of a radiator depends on whether your goal is to heat the room or cool some device. It is another question anyway. My guess would be it's there to prevent the cooling air from accumulating below the window and flowing into the rest of the room. A number of reason: - the wall under the window is basically useless - placing the heater under the window allows you have a more even temperature throughout the room: the window is the coldest place in the room, if you were to place a heater on the other side of the room and wanted to reach a certain temperature by the window, the other part of the room would have to be much hotter.

As the hot air goes up and the cold air goes down, the radiator is located where there is a better circulation, ie, even though the window is double glazed, there will always be cold air entering the division by the material itself. Its because the hot air that is created by the radiator heats the colder window making the glass warmer Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Why are radiators always placed under windows? Ask Question. Asked 7 years, 11 months ago. Active 1 year, 9 months ago. Viewed 56k times. Improve this question. Brandon Enright Placing a radiator under a window evens up the feel of a room. This is fairly uncomfortable for the occupants. Add a comment. Active Oldest Votes.

Improve this answer. No, indeed the heat loss increases as the difference in temperature is bigger, so wouldn't it be the opposite? That creates a "curtain" of moving air that helps insulate the interior of the room from the chill of the window. Moving hot air has less time to transfer its heat to neighboring cold air. Whether that's actually what happens seems like a hard-to-answer empirical question. The math required to analyzed such a system is too much for me to manage right now, but I believe the following principles apply and are objectively correct: The dissipation of heat through the glass will increase in proportion to the difference of the indoor and outdoor temperatures; the larger the gap, the faster the loss of energy to the room.

Back in the days of single glazing this made sense and resulted in most rooms having a radiator installed under the window, however is it still relevant today? In the modern world, all new-build housing and the vast majority of refurbishments include installation of double glazing as standard. It's long been recognised that double and even triple glazing is much better at preventing heat loss out of a window, keeping a room warmer for longer and using less energy.

In addition, many houses have cavity wall and loft insulation which also greatly improves energy efficiency and decreases heat loss. These technological improvements to building standards means that you do not have to install radiators under a window and have greater flexibility when it comes to placement. Where they might once have been a bit of a novelty, vertical rads have become standard and are available with as many size and finish options as their horizontal counterparts.

We are living in increasingly smaller houses and apartments which often results in a lack of horizontal wall space. Vertical radiators make fantastic use of upward space, allowing small or awkwardly shaped rooms to have the right amount of heat. Vertical radiators also mean that narrow walls or the space next to large windows or patio doors become perfect places to be installed.

Traditionally these areas would have been impossible to heat adequately due to the limitations of horizontal radiators. Installing a radiator under a window is still a very good option.