# position of radiators & curtains?



## Gordanus (13 Feb 2009)

another heating insulation question:
the radiators are all under windows in my house. The cold spell has really made me think whether this is a good idea - but I can't afford to move them. So: should I get shortish curtains that can hang over the windowsill and be tucked behind the radiator (or does this mean that half the heat is going up the inside of the curtains?)
Or what is the best design??

there's no way that the curtains will fit inside the window alcove - the windowsill is only about 2 inches wide. But I have double glaxing and blinds on the inside and then the curtains go over that. (Still freezing though, but I am very susceptible to cold)

Sorry mods, just noticed the home energy forum, could you move this? (Done).


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## Smashbox (13 Feb 2009)

Could you put the curtains on the sill with some small weights or post of some kind?


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## Padraigb (13 Feb 2009)

I never did get the idea that radiators should be placed under windows. The only justification I can think of is saving wall space to allow more options for placing furniture, but it seems to be a standard practice in the minds of some builders and designers.

You might look at the idea of putting shelves above the radiators (easily done, and kits are available) and having curtains just long enough to meet them.


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## Chocks away (13 Feb 2009)

Hi Gordanus, we had the same problem. A few years ago while refurbing the builder put a protruding wooden ledge all around the bay window and I made new curtains fit. These lie on the ledge about 2" behind the rim. The builder told me that the reason that rads were under windows was that in the old days, the cold air dropping down from the single pane of glass would heat and so start a thermal current. Makes sense.


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## RMCF (13 Feb 2009)

I had always thought that radiators were placed under windows to allow the best circulation of the heated air. But here are 2 different views from other internet sites:

1)
The reason radiators (or heating registers for forced air heating) were placed under windows was to reduce drafts due to the heat loss from the window itself (as windows used to be single glazed). As windows become more thermally efficient, there's less reason to do this these days, though old habits die hard. Another reason is that furniture tends not to be placed under windows so placing radiators/heating registers there conserves wall space as that space wouldn't otherwise be used.

2)
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. So the cold will push the hot air inside the room. Another explanation can be the fact that external walls can have thermal bridges and cold air can enter the room and cause heat loss. By placing the radiator on the exterior wall, the thermal bridge will still exist, but the effect of cold air entering the room, will be compensated by the heater (in environmental terms, it isn't good at all to have thermal bridges in buildings, but it is cheaper to build). Today, we can see radiators and heaters either underneath the windows or close to the maximum number of doors, as the temperature in the rooms vary and helps air circulation.


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## Pique318 (13 Feb 2009)

When our house was being built, we had all rads moved from under the windows to the internal walls....my logic is similar to those above....heat will disappear through the glass or be cooled by the cold air at that point before even getting to the rest of the room and in my mind is very inefficient.
Now we have heat at the central 'core' of the house which then moves outwards and the loss through the windows is minimised. Also, the walls are heated by the rads and will store a bit of the heat after the heating is off, which would not happen if the rads were on the external walls.


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## DGOBS (13 Feb 2009)

RMCF above is correct, the best place for radiators to be placed is under the window, it sets up the best thermal circulation for a room.....

that is simply...

hot air hits the window, quickly cools and falls passin the radiator as it does, unlike its name, a radiator heats mainly by convection, so heats the passing cool air, that moves across the room rinsing from floor to mid level (that we live in) as it does, rising the the ceiling at the far end of the room and travelling accros the higher portion of the room (that we dont ocupy) towards the window as it cools and agin finds to cold window and the cycle starts again.

So the theory goes under the window is best


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## RMCF (13 Feb 2009)

Although the logic of what I had always believed sounds solid enough, what Pique318 says above also sounds fairly logical too.

Any thoughts on that?


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## DavyJones (13 Feb 2009)

I think it would depend, what are the internal walls made of? How well are exterior walls insulated? etc.

I am from the school, that belives rads should be under windows, hot air meeting a cold front and causing a tumbling circulation effect. it has been well explained already.


However, when I receive drawings of houses, radiators are usually marked out as part of the design of each room.I.E planned location of furniture, beds,wardrobe etc and as RMCF has pointed out, sometimes the only availible space is under window. 

Where rads are under windows I always ask clients about curtains, curtains hanging over rads is sinfull. best to be avoided.


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## niceoneted (14 Feb 2009)

I would be interested to know what type of heating Pique318 has, also size of house and how much are the bills. 
I am of the thought that rads should be on external walls, I put my curtains behind them. I have one room where the rad is not on external wall - I did request builder move it when buying but they would not. It is I have to say the hardest room to heat!


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## extopia (14 Feb 2009)

Rads should be placed at the coldest spot in the room to maximise convection efficiency. Usually that means under the windows. Trying to create a heat sink by placing your rads on internal walls is a waste of time. 

Who said you'd never put what you learned in leaving cert physics to good use?


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## Lex Foutish (14 Feb 2009)

extopia said:


> Rads should be placed at the coldest spot in the room to maximise convection efficiency. Usually that means under the windows. Trying to create a heat sink by placing your rads on internal walls is a waste of time.
> 
> Who said you'd never put what you learned in leaving cert physics to good use?


 
Hi Extopia. What about Leaving Cert Irish......?

Seanbhean is ea mé anois atá cos leí san uaig is an cos eile ar a bhruach...............!

Ah, happy days!


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## extopia (14 Feb 2009)

"Tá sé fuar" arsa an seanbhean,

"Is é atá" arsa Séimi. "Fuar, fuar."


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## Lex Foutish (14 Feb 2009)

How're you on Cath Ceim an Fhia? Or Caoineadh Airt Uí Laoighre?

I did my Leaving Cert in the 70's. Not sure when you passed out.

My wife gets a little concerned sometimes when I start spouting Irish poetry! I used to love it!

Cága i nead an Ghaill,
Drisleach is eidhneán tiubh.
Clann Riocáird bhí tréan, 
Cá bhfuil a réim inniu?


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## Lex Foutish (14 Feb 2009)

I'm not sure if Brendan or the Mods will be too impressed with this conversation going on under *Home Energy*.

Tá brón orainn, a Bhreandán! Agus do lucht leanúna iontach!

Just a thought...... Ní fheadar, an raibh insulation ag Peig ina teach ar an mBlaoscáid Mór?

Do bhí! *Díon tuí!* 

Ní bheidh a leithéid ann arís!


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## Padraigb (14 Feb 2009)

Lex Foutish said:


> Just a thought...... Ní fheadar, an raibh insulation ag Peig ina teach ar an mBlaoscáid Mór?
> 
> Do bhí! *Díon tuí!*



Not true. There wasn't much straw available on the Blaskets. The first house she lived in had a tarred felt roof, and the later house had a slate roof.

But there are lessons to be learned from vernacular architecture (albeit not about the placing of radiators): small windows; houses built in the lee of hills; thick stone walls; thatch, where materials were available. [Peg's final home was provided by the Congested Districts Board, and ignored those principles.]


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## Gordanus (14 Feb 2009)

Chocks away said:


> Hi Gordanus, we had the same problem. A few years ago while refurbing the builder put a protruding wooden ledge all around the bay window and I made new curtains fit. These lie on the ledge about 2" behind the rim. The builder told me that the reason that rads were under windows was that in the old days, the cold air dropping down from the single pane of glass would heat and so start a thermal current. Makes sense.



Thanks! Brilliant idea, and cheap too!

paidraigb, I always did wonder how Irish homes never seem to take account of climate...in towns anyway.


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## Ryluer (1 Dec 2013)

With modern double glazing its not important to locate radiators under windows anymore.

And many new builds have a window design that won't allow the space for a rad. So many plumbers locate the radiator/s on the internal wall.

Which is more energy efficient anyway!


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