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

beer2006

I know me and ken talked a bit about this last year.
I made some (very nifty even if I say so ) panels up last year with thick cardboard, silver foil on the front and bubblewrap behind.

Now I have an old house with single skin walls so I expect anything I do to stop heat escaping from behind the radiator will be more of a effect than for cavity walls. My walls are extremely cold anyway, so even that must be dragging out the heat.

So I fitted these at about feb last year I think. We are on oil heating here, our oil consumption has definately dropped, obviously I can't say its because of these panels, other variables are around as well. But the one thing we noticed straight away, is that we felt warmer, the radiators seemed to be putting out more heat.

I won't be taking them out.

Ken68

I'm saving the silver foil from tea packets, so as to make another............I'll get me coat...

beer2006

Ken68 wrote:

I'm saving the silver foil from tea packets, so as to make another............I'll get me coat...

Unless you drink alot of tea, you will be needing it

djohn2002uk

One other thing that Ken and Cardew fail to mention (or appear to take into account) is the fact that all the heat behind the radiator that would be heating the wall, is now being reflected into the room (the reason for reflectors on electric fires), and this must be making some difference to the temperature and therefore causing the thermostat (of whichever type) to shut off sooner.
Possibly also a reason for Beer2006 feeling warmer.

beer2006

Yep, what I remember reading is that the radiator stays hotter, as the heat is being reflected back into it, I think thats the main purpose of the panels.

masonic

djohn2002uk wrote:

...is the fact that all the heat behind the radiator that would be heating the wall, is now being reflected into the room (the reason for reflectors on electric fires)

Well, not all of it; just the radiant heat. That part of the wall will still be heated through convection of the air passing behind the radiator.

beer2006

Well OK, but obviously thats the only type of heat you can deal with with this type of panel. Unless of course it ran all the way to the top of the wall and onto the ceiling. But presumably hot convective air passing up the rear of the rad will not be cooled by the non cold wall?
Also because it will be hotter behind the radiator, convective heat will rise faster and therefore should disperse quicker?

Conduction losses I suppose could be dealt with by having an insulating material between the radiator brackets and the wall, but I would think this was a small amount.

edit
Actually thinking about it, my panels have a panel sticking at an angle into the room, on radiators where we have windows above them, it enables us to nicely put the cutains behind it, on others I feel it maybe pushes the hot air away from the cold wall.
I don't know this of course, only guessing.

Cardew

djohn2002uk wrote:

One other thing that Ken and Cardew fail to mention (or appear to take into account) is the fact that all the heat behind the radiator that would be heating the wall, is now being reflected into the room (the reason for reflectors on electric fires), and this must be making some difference to the temperature and therefore causing the thermostat (of whichever type) to shut off sooner.
Possibly also a reason for Beer2006 feeling warmer.

The point of this discussion is not whether these panels will have some effect or not; I have already conceded they will probably save some cost.

What I was challenging is the OP’s assumption that they will save “10% -20% off your total heating bill” - and he did ask if he had missed the point!

Look at any independant website that gives the payback times for cost saving measures(10" roof insulation, HW jacket, Draught proofing etc) and these panels don't get a mention.

masonic

beer2006 wrote:

But presumably hot convective air passing up the rear of the rad will not be cooled by the non cold wall?

The hot air passing up the rear of the radiator will indeed heat the wall, even with a reflective panel in place - this type of insulation will have no effect on that. In fact, I suspect the convection losses (from the hot air passing behind the radiator and heating the wall) are more significant than radiative losses (that a reflective panel would prevent). Radiation from a radiator actually lends only a minor contribution to the overall heat they emit. The term 'radiator' is widely accepted to be a misnomer: they should have been called 'convectors'.

Actually thinking about it, my panels have a panel sticking at an angle into the room, on radiators where we have windows above them, it enables us to nicely put the cutains behind it, on others I feel it maybe pushes the hot air away from the cold wall.

...and gets heated by this air in the process. However, I doubt there is much difference to what happens above the radiator whether there is reflective panelling or not.

Edit: Missed one!

Also because it will be hotter behind the radiator, convective heat will rise faster and therefore should disperse quicker?

It will rise faster. However, because it is hotter, it will also heat the wall faster. I don't know how these factors would weigh against each other.

beer2006

But it has bubble wrap on the back, how can you say it can't stop the convection heat being cooled by the wall?
Not above the rad, obviously, but behind it.

Its true btw that the flaps sticking out do get heated to a certain extent, but the alternative is to have the curtains hanging down (its the mrs, she insists on long curtains)