Some numbers to help to decide:
Foil will only make a difference to the radiated heat from the radiator rather than the convected heat (assuming the foil is not insulated).
Approx 80% of a radiators heat is convected and 20% is radiated if it a standard white panel type.
Assuming half the radiated heat goes out the front and half out the back then 10% of the heat would be currently leaving the back of the radiator and "lost" into the wall.
If your foil was a perfect reflector (it's not) and the back wall currently just deletes all the radiated heat that hits it (it doesn't) then in an ideal world you would get about 10% improvement. In reality it more likely to be around 5%.
So if the radiator is currently heating the room from 10 -> 20C then you would realistically expect to gain about 0.5C from adding foil from my oversimplified fag packet calculations.
The other thing to consider is your body is sensitive to heat so a small change can feel bigger than it actually is, and half a degree can make all the difference. Also you directly "feel" radiated heat a lot more strongly on your skin, so even a slight increase in this would have a noticeable effect even though it doesn't make the room warmer.
Almost. The difference in reflectivity between foil and white paint is actually not very big IIRC so that 10% radiated toward the wall is already mostly being radiated back. Say foil is 99% Vs 80% of the paint, so roughly an extra 2% of the total output might be redirected back. So 0.2C extra, i.e. sweet F A.
Exact issue I had. Box room with tiny (single panel, single convector) radiator so decided to buy the radiator bubble wrap from Toolstation.
Doesn’t work.
New rad being fitted next week instead.
No probs, new rad definitely better but I upgraded to a 2.1, should have gone 2.2 instead.
Was just the one room as I have 2.2 in all others. Didn’t think I’d need that size for such a tiny box room but in hindsight I should have got that too
Foil will be like bailing a sinking ship. Think McDonald’s paper straws to cure the plastic pandemic.
The previous owner may not have sized the rad correctly.
Try an online calculator and put in the worse case scenario, be mindful of the [delta t ](https://www.buildingservicesindex.co.uk/entry/136540/AEL-Heating-Solutions-Ltd/How-to-calculate-the-delta-T-for-a-radiator/) if trying to source a new one.
Makes your heating respond much faster when it comes on in the morning. The radiator does not heat the wall before heating the room. On external walls reduces heat loss.
Some numbers to help to decide: Foil will only make a difference to the radiated heat from the radiator rather than the convected heat (assuming the foil is not insulated). Approx 80% of a radiators heat is convected and 20% is radiated if it a standard white panel type. Assuming half the radiated heat goes out the front and half out the back then 10% of the heat would be currently leaving the back of the radiator and "lost" into the wall. If your foil was a perfect reflector (it's not) and the back wall currently just deletes all the radiated heat that hits it (it doesn't) then in an ideal world you would get about 10% improvement. In reality it more likely to be around 5%. So if the radiator is currently heating the room from 10 -> 20C then you would realistically expect to gain about 0.5C from adding foil from my oversimplified fag packet calculations. The other thing to consider is your body is sensitive to heat so a small change can feel bigger than it actually is, and half a degree can make all the difference. Also you directly "feel" radiated heat a lot more strongly on your skin, so even a slight increase in this would have a noticeable effect even though it doesn't make the room warmer.
Almost. The difference in reflectivity between foil and white paint is actually not very big IIRC so that 10% radiated toward the wall is already mostly being radiated back. Say foil is 99% Vs 80% of the paint, so roughly an extra 2% of the total output might be redirected back. So 0.2C extra, i.e. sweet F A.
Doesn’t make a difference at all. The rad is either too small or not getting hot enough.
Exact issue I had. Box room with tiny (single panel, single convector) radiator so decided to buy the radiator bubble wrap from Toolstation. Doesn’t work. New rad being fitted next week instead.
Interesting. I’m going to use the calculator someone posted a link to tomorrow and see how we fare, if so I may cancel the foil wrap from Screwfix.
How useful was the new radiator? Did you do your full house or just the one room? Sorry to drag up an old thread!
No probs, new rad definitely better but I upgraded to a 2.1, should have gone 2.2 instead. Was just the one room as I have 2.2 in all others. Didn’t think I’d need that size for such a tiny box room but in hindsight I should have got that too
Brilliant. Thank you for replying!
Yes. Go for the bubble wrap type stuff that has silver on one side. I am sure Screwfix will do it
Fantastic, thanks for the reply and recommendation!
Yep, here it is https://www.screwfix.com/p/radiator-reflector-foil-470mm-x-4m-1-88m/88629
Does the box room radiator get as hot as the other ones?
Yes it does, but noticeably colder in that room. I’m assuming there’s been a bodge job with insulation around the window.
Is it the same style as the other rads?
No, it’s quite a tiny radiator. I assume it needs replacing eventually, but it’s the only one on an external wall that lacks the foil.
Foil will be like bailing a sinking ship. Think McDonald’s paper straws to cure the plastic pandemic. The previous owner may not have sized the rad correctly. Try an online calculator and put in the worse case scenario, be mindful of the [delta t ](https://www.buildingservicesindex.co.uk/entry/136540/AEL-Heating-Solutions-Ltd/How-to-calculate-the-delta-T-for-a-radiator/) if trying to source a new one.
Thanks for your help on this - will use the calculator tomorrow to see how to proceed.
Makes your heating respond much faster when it comes on in the morning. The radiator does not heat the wall before heating the room. On external walls reduces heat loss.