Do insulated radiator panels save money? - I'm testing them now

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  • masonic
    masonic Posts: 23,068
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    beer2006 wrote:
    But it has bubble wrap on the back, how can you say it can't stop the convection heat being cooled by the wall?
    In that case, you have more than just reflective panels. You have additional wall insulation, if you like. Some of the heat is being reflected (radiative). Some of it is warming the relective surface (convective), but the insulation (partially) prevents it being conducted to the wall itself. So, the question is whether the reflective part is really necessary? Bubblewrap itself might be almost as good.
  • beer2006
    beer2006 Posts: 1,987
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    masonic wrote:
    In that case, you have more than just reflective panels. You have additional wall insulation, if you like. Some of the heat is being reflected (radiative). Some of it is warming the relective surface (convective), but the insulation (partially) prevents it being conducted to the wall itself. So, the question is whether the reflective part is really necessary? Bubblewrap itself might be almost as good.
    Which you would then say was absorbing the radiative heat :rolleyes:
    Which is why we have foil covered bubble wrap effectively.
    “Pleasure of love lasts but a moment, pain of love lasts a lifetime.”
  • masonic
    masonic Posts: 23,068
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    beer2006 wrote:
    Which you would then say was absorbing the radiative heat :rolleyes:
    I can't resist pointing out at this point that the radiative heat would probably not be absorbed by the bubblewrap as it passed through. ;)

    My point was: if you are going to add insulation, then are these really just reflective panels, or are they acting mainly as bog standard insulation? Sure it's worth having a reflective surface - every little helps, but perhaps 'reflective panel' is then a misnomer, just as 'radiator' is a misnomer.

    BTW, if it hasn't already become apparent, I was using the term 'reflective panel' in the above discussion to mean just that - tin foil - in my original response to djohn2002uk. Though I know you discussed the foil/bubblewrap combination before I joined this discussion, you didn't mention it again until just then. Our discussion has related to different things. :rotfl:
  • beer2006
    beer2006 Posts: 1,987
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    I wonder how much the radiated heat would be stopped by the trapped air in the bubblewrap? Redundant thought anyway, as it has foil on it and it would be neglible compared to that presumeably.

    I assume that all of these panels have a certain amount of insulation in them as well as a reflective layer. Thats what I was working on.
    It certainly would seem so, text taken from the "My tech" link on previous page.

    "Properly designed reflective panels, which combine reflective foil with a thin layer of insulation, can reduce the heat lost through walls by up to 18%."

    As an afterthought I remember reading somewhere that std kitchen foil loses its shinyness after a while and stops being such a good reflector, I think the commercial panels have some non dulling surface on them.
    “Pleasure of love lasts but a moment, pain of love lasts a lifetime.”
  • masonic
    masonic Posts: 23,068
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    beer2006 wrote:
    I wonder how much the radiated heat would be stopped by the trapped air in the bubblewrap? Redundant thought anyway, as it has foil on it and it would be neglible compared to that presumeably.
    The only constituent of air that has any real infra-red absorption is CO2 (and that only has two very narrow bands of absorption), so in answer to your redundant thought, next to none. The plastic could absorb some though, depending what's in it.
    I assume that all of these panels have a certain amount of insulation in them as well as a reflective layer. Thats what I was working on.
    It certainly would seem so, text taken from the "My tech" link on previous page.

    "Properly designed reflective panels, which combine reflective foil with a thin layer of insulation, can reduce the heat lost through walls by up to 18%."
    Agreed, and the insulation is clearly pretty crucial to their effectiveness. I'd still like to know what that 18% related to. ;)
    As an afterthought I remember reading somewhere that std kitchen foil loses its shinyness after a while and stops being such a good reflector, I think the commercial panels have some non dulling surface on them.
    You can always replace the foil, though, or cover it in cling film.
  • beer2006
    beer2006 Posts: 1,987
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    masonic wrote:
    You can always replace the foil, though, or cover it in cling film.
    Ahh but the plastic in the clingfilm would absorb the radiated heat ;)

    :rotfl:

    Actually the clingfilm is a good idea, assuming it doesn't melt or get distorted by the heat, or fall off, maybe a clear thin glue, following on......... some sort of thin clear layer painted on the foil. Clear varnish?
    “Pleasure of love lasts but a moment, pain of love lasts a lifetime.”
  • masonic
    masonic Posts: 23,068
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    beer2006 wrote:
    Ahh but the plastic in the clingfilm would absorb the radiated heat ;)

    :rotfl:

    Actually the clingfilm is a good idea, assuming it doesn't melt or get distorted by the heat, or fall off, maybe a clear thin glue, following on......... some sort of thin clear layer painted on the foil. Clear varnish?
    :rotfl: I saw that coming! WD-40 might do the trick, though if you do go down the varnish route, do let it dry before you hang it behind the radiator. :D
  • Cardew
    Cardew Posts: 29,036
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    beer2006 wrote:
    text taken from the "My tech" link on previous page.

    "Properly designed reflective panels, which combine reflective foil with a thin layer of insulation, can reduce the heat lost through walls by up to 18%."

    As both I and Masonic have asked above, what does that 'up to 18%' relate to?

    Firstly I have grave Suspicions when the phrase “up to” is used; as that covers from 0.001% upwards.

    Secondly up to 18% of the wall area behind the radiator? It surely cannot possibly be 18% of the total loss through all walls?

    Lastly given that total heat loss through all walls is normally 20-30% even in the unlikely(impossible) event that it saved up to 18% of the total loss through all walls, you are talking of 4-5% of total heating.

    My guess is they will save less than 1% of total heating bills; around £5 a year for most.
  • masonic
    masonic Posts: 23,068
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    Cardew wrote:
    It surely cannot possibly be 18% of the total loss through all walls?
    That claim would seem pretty absurd to me also, since unless you have a lot of radiators I can't see the space behind them totalling anything close to 18% of the total external wallspace in a house. So even if the panels were 100% efficient at preventing heat loss through the area of wall behind them, they could not live up to that claim unless the temperature of the wall behind the radiator (relative to the temperature outside) was several times higher than that of the rest of the wall.

    Edit: On thinking about this further, I'm starting to consider an 18% reduction on the total loss through all walls to be somewhat less far-fetched. I estimate about 5% of the area of my external walls are behind a radiator. If I were heating my house to 20 °C and it was 10 °C outside, in order to see an 18% reduction the area of wall behind the radiators would have to be losing heat 3.6 times faster than the rest of the wall area. That would equate to a wall temperature difference 3.6 times greater than 10 °C: namely 36 °C more than 10 °C (so a wall temperature of just under 50 °C behind the radiator). Now that does not seem unreasonable. This is all assuming a 100% efficient insulating panel, though.
  • beer2006
    beer2006 Posts: 1,987
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    Cardew wrote:
    As both I and Masonic have asked above, what does that 'up to 18%' relate to?
    Its no good getting shirty, I was only copying a link as I said, why don't you go and find out?
    “Pleasure of love lasts but a moment, pain of love lasts a lifetime.”
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