Best position for radiators

[str]

Planning on having work carried out which will include the need to relocate a number of radiators (mainly in bedrooms) and install new raditors.

Is there any difference on where a radiator is fitted within a room? Had heard that its not that effecient to have a radiator under a window due to the cold air coming in cooling the warm air but this could be complete nonsense.

Was thinking that it would be handy to put them behind doors which open towards a wall as its dead space anyway?

is it just personal preference or anything more scientific than that?

 

[JohnD]

not under windows as heat loss is greatest and curtains may funnel the heat outside

not where you will put furniture

on an interior wall will lose less heat than an external one esp if solid or unfilled

also look at joist runs to make it easiest and avoid notches

 

[str]

so behind a door, assuming there is enough space/clearance, would be okay on the basis that the door will be closed meaning that heat output isn't blocked

 

[JohnD]

s/be OK. Dual panel rads with fins are quite thick so make sure the door won't bang it.

 

[swidders]

not under windows as heat loss is greatest and curtains may funnel the heat outside

So we don't use convection currents anymore ? Since when have the laws of physics changed - the whole point is that the radiator will counteract the draft of cold air coming off the window and create a circular convection current. Also, get shorter curtains!!

not where you will put furniture

85% of heat comes from convection, not radiation, so providing there is space above and below to allow for circulation then this won't be a problem.

on an interior wall will lose less heat than an external one esp if solid or unfilled

Use reflector panels behind the rad.

also look at joist runs to make it easiest and avoid notches

Why cut any notches at all then - you could have the whole lot surface mounted. Either do the job right or not at all!

You could have a slightly smaller radiator under the window if those with recommended output are too large aesthetically, and don't provide a minimum of 150mm underneth, and a single panel top-up near the door. This works well

 

[JohnD]

not under windows as heat loss is greatest and curtains may funnel the heat outside

So we don't use convection currents anymore ? Since when have the laws of physics changed - the whole point is that the radiator will counteract the draft of cold air coming off the window and create a circular convection current. Also, get shorter curtains!!

If you put a radiator under a window, YOU WILL lose more heat straight through the glass.

This is wasteful of energy = money = yet more global warming.

It is because you have a greater temperature gradient.

Your circular convection current will keep the birds in the garden nice and warm, if that's what you really want.

If you put the rad somewhere else you can have whatever curtains you want.

I think you are just being argumentative about the other points as well.

 

[swidders]

If you put a radiator under a window, YOU WILL lose more heat straight through the glass.

This is wasteful of energy = money = yet more global warming.

It is because you have a greater temperature gradient.

Your circular convection current will keep the birds in the garden nice and warm, if that's what you really want.

If you put the rad somewhere else you can have whatever curtains you want.

On the other hand, if you put the radiator elsewhere you can have an entire wall (with a window) remaining very cold, and which ensures that you require a heck of a lot more energy being used to complete the convection loop.

I think you are just being argumentative about the other points as well.

Not really - just stating the facts. It's not me who's ignoring conventional wisdom.

 

[cjard]

And for the Government Advice on this topic:

http://www.west-norfolk.gov.uk/default.aspx?page=22426


Basically, whether to put your radiators under your windows or not depends on the length of your curtains. Get curtains that are the correct length, and put your radiators under the window.

Or sack the rads off all together and fit underfloor or forced air heating

 

[cjard]

If you put a radiator under a window, YOU WILL lose more heat straight through the glass.

Omm.. But.. Radiators don't radiate, they convect. Radiated heat passes straight through glass, but the convected heat doesnt. When all is said and done, the window represents a cooling panel and the radiator a heating panel. If you site these at opposite sides of a room you generate a thermal circulation that will eventually stabilise such that the top of the room is warm and the bottom is cold, but while it is stabilising, the air moves and becomes a draught. If you're not aware of the concept of windchill, then simply put; a human who has air at 10degC blown over them will feel colder than someone who is standing in air that is 10degC and not moving. Ergo, the cycling air will cause the humans sitting in (the draught) to feel colder than normal. Putting the rad under the window combats/disrupts this circulation

It is because you have a greater temperature gradient.

From where, to where?

Your circular convection current will keep the birds in the garden nice and warm, if that's what you really want.

But there is no route from inside to outside for this warm air to escape and heat the birds! Your warm room establishes a temperature gradient across the window, but you can say the same for every surface in the room. What we're attempting to control witha rad under a window is not the temperature gradient across the glass from inside to outside, but the downdraught of air that has a detrimental effect to the perceived temperature of the room

If you put the rad somewhere else you can have whatever curtains you want.

If you put the rad somewhere else you'd be advised to get floor-to-ceiling curtains that completely occlude the window in every way, to reduce the circulation of air that will be perceived as a draught

I think you are just being argumentative about the other points as well.

I understand your thinking, but a physicist may disagree. That said, entire university courses on fluid dynamics exist so there is the potential to get a lot more complicated in this discussion

 

[gas4you]

I personally like to install the radiators in the natural cold spot of the room. This could be under the windows or next to a patio door for example.

It is best to warm the cold spot first then the rest of the room warms more evenly.

If you put the radiators on a wall opposite the cold spot, then if you sit in the cold spot you will always feel cold even though the rad may be technically the correct size for the room.

 

[swidders]

It seems fair to believe that a local government's advice is compliant with Part L1 Regs on conservation of fuel and power?

 

[cjard]

Thats a thought, does Does Part L mention where to site them?

 

[mogget]

Putting radiators on an internal wall can cause condensation problems, because warm air can hold more water vapour than cold air.

What can happen is this - the radiator is sited on the interior wall, and heats the air which then rises due to convection. As the air passes across the room it can absorb moisture from breathing, clothes drying, even hot cups of coffee. The warm air then reaches the window, and cools, with the result that it dumps its load of moisture on the window and the wall below. Then the cycle continues.

Also, with the radiator on the internal wall, the convection is much faster than if the radiator were under the window, so although the current of air across the window is cooler, there's much more of it. I suspect that it doesn't make a lot of difference to the heat lost.

Then there's the human factor. If people's feet are cold due to a downdraught from the window, they're likely to turn the temperature up much higher than it would need to be if there were no draught!

 

[swidders]

Thats a thought, does Does Part L mention where to site them?

Well, have just skimmed through it as well as Domestic Heating Compliance Guide, ZZZZZZZZZZZ snore ZZZZZZZ, and it's not jumping out - other than "most efficient use...."

 

[swidders]

What can happen is this - the radiator is sited on the interior wall, and heats the air which then rises due to convection. As the air passes across the room it can absorb moisture from breathing, clothes drying, even hot cups of coffee. The warm air then reaches the window, and cools, with the result that it dumps its load of moisture on the window and the wall below. Then the cycle continues.

So, it would save money and energy if you relied on this and a towel rather than an air de-humidifier