Radiator Insulation

[JoceAndChris]

Does it work? I'm thinking of the sticky foil that supposedly radiates the heat from behind. My rad is off in the dining room for painting and I'm just wondering if it would be worthwhile putting this stuff on the wall before rehanging the rad.

It's going under the window, and is 2 metres long.

PS I ought to point out that that wall is one of the dampest, the weather hits the bare stone where the render's off.

 

[AMc]

Yes it works - I covered a panel of cardboard with cooking foil and blutacked it behind the radiator in one of our rooms before the underfloor heating was done.
It made a small but noticeable difference. I see no reason at all to use anything more complicated or expensive.

 

[Lime]

My comment assumes a modern radiator is fitted......

Efficiency can be increased if the radiator is projected further into the room.
Most modern radiators only allow the absolute minimum clearance between the wall and the radiator.
Any increase will allow more heat to enter the room and less heat loss through the wall.
Simple wooden battens placed between the radiator fixings and the wall are all that is needed.

 

[JoceAndChris]

That's interesting Lime - I wasn't aware of that. I'll see if Chris will do that then. They are just nasty modern rads in this house so are pretty slim. The aim is to get covers eventually, that can lift off in the coldest winter months.

A great idea about backing card with foil- in that case the radiators don't really need to come off and the board can just be lifted in and out according to season.

I'll go ahead with it, many thanks!

 

[AMc]

The clue is in the name "radiators"; they radiate heat (and convect and conduct too).

If you look at the front and back of them they're basically the same so they radiate heat more or less equally into your room and your uninsulated wall. The wall warms a bit and radiates some of that heat into the room too, but a great deal is conducted away to the outside of the building and into the night.
The foil works by reflecting some of the infrared radiation back at the radiator and into the room. The air moving behind the radiator is also warmed and rises up dragging up cold air from the floor to be warmed (convection).

The commercial radiator reflectors have ridges in the foil to improve convection or alter the reflection but I'm sceptical that it makes enough difference to cover the cost.
http://www.goodenergyshop.co.uk/Gift+Ideas%2fGifts+for+the+home%2fHeatkeeper+Radiator+Insulation+Packs
Independent research seems to indicate they work but they only quote the positives
http://www.goodenergyshop.co.uk/Library/Categories/Heating/INDEPENDENT%20REPORTS%20on%20Heatkeeper%20Novitherm%20panels.pdf

Lime's suggestion sounds like a good one, assuming you have good sized rooms. Increasing the gap behind the radiator will make it easier for air to move up behind the radiator and increase the convection current. The wooden batten will also insulate the mountings meaning less heat is conducted into the walls - not a major loss but still an improvement.

I got some bespoke bookshelves and cupboards made up by jali.co.uk who CNC MDF to order. They now send me their email newsletter, their primary business is selling made to measure MDF radiator cabinets. One of their most recent ones went on about "radiators" being really being "convectors" and so a cover made them only a little less efficient - personally my A level in physics caused me to question their logic but I profess no solid scientific study to back that scepticism.
As you tell us your bills are high and your house is cold, I'd seriously consider spending money on radiators you like rather than covers that will reduce the efficiency of the ones you've got and still (IMHO) look wrong.

 

[JoceAndChris]

Lots of lovely and sensible advice there AMc- I can't believe I'm only just now getting round to foiling having read all that.

Regarding buying rads I like, rather than covers -it becomes very difficult when you've got antique boards you don't want to lift (and maybe ruin) and £800 of wallpaper on the wall. Replacing the radiators here would mean lifting antique floorboards in 5 rooms and re-wallpapering three walls. I've kept spare rolls but I think in some cases the wallpaper on the wall has faded and the spares haven't so it would show. We discussed buying new radiators at length but ultimately decided we couldn't afford it and it would be a shame to ruin the flooboards.

I love the column rads but I think bespoke cabinets are equally nice. The plan was to customise them so they lift off the rads from December-Febuary. They're right at the bottom of the shopping list though so I've steeled myself for many years of looking at ugly radiators! Fortunately in most cases they're partly covered up by curtains and furniture.

 

[robgil]

It depends on what type of radiators you use , most if the useful heat from a radiator goes up from the top of the radiator, it wont hurt to try and reflect any heat from behind but to be fair I doubt you will notice it.
A better idea is to have a large window sill to push convected heat away from the window and into the room, this should not interfere with the radiators job of stopping cold downdraught's over the window.

If you choose radiators with double panels then foil will be more useful, if the back of the radiator has just fins it might not make that much of a difference but it wont hurt either.

Edit - cast rads are cheap if you are willing to put some time and elbow grease into them. This one cost me £12, £17 after paint.

 

[AMc]

It depends on what type of radiators you use , most if the useful heat from a radiator goes up from the top of the radiator, it wont hurt to try and reflect any heat from behind but to be fair I doubt you will notice it.

The research I linked shows 15% (or greater) improvement - I'd take a 15% reduction in fuel bills for a bit of blue peter time with the foil and cardboard The window cill idea sounds interesting - if your rads are under the windows - my remaining ones aren't due to very low cills

Joce - are you sure you need to lift the floors to replace the radiators? You might be able to route the existing pipes to new shapes/sizes providing the basic footprint is similar - cast rads come in a load of different shapes and styles.
If the boards were lifted to install the existing system then you may find lifting them again isn't destructive. I lifted 150-200 year old boards in one bedroom to deal with a pipe noise problem and in two other rooms to fit underfloor heating. At least one room hadn't been disturbed in living memory judging by the massive rat skeleton and absence of any wiring, pipes etc. underneath the floor.

 

[JoceAndChris]

Thanks for the posts. AMc -well done on lifting your floorboards - it sounds like you've been very gentle and careful with them. Chris thinks a fair number would need to be lifted here for new rads and that they would break - we've already had a couple of disasters, not from him but his Dad (who's a very good plumber, but not great at respecting antique floorboards).

Maybe one day, later on in the 25 year project.

Rob, I'm so impressed with your radiator steal and renovation! That looks great - I remember your bathroom taps too - a real inspiration. I'm sure I'll be asking you for advice in the future as there are three or four rooms remaining where we could do as you've done. (One room has a flagstone floor and one room a lime ash floor - how you go about working through those sorts of floors I've no idea but will ask when the time comes!)

The sill idea is interesting in a house that required new sills but once again I couldn't touch the Regency sills here and alter their proportions, plus the floor to ceiling curtains would have to go and there's no way I'm parting with those!

 

[Juju]

I put foil behind all our radiators on external walls last year - I have no idea if it makes a difference but everyone says it does and I feel better having done it! The next job is to find the forum thread I think we had last year on all the other good ideas for keeping the heat in and put them into action - eg curtain linings etc (I've found some blankets for the job). Does it really make a difference keeping internal doors shut? I leave ours open during the day so I get light into the house - I hate the dark hallway and landing otherwise but if it definitely helps keep heat in the rooms, then I'll do it.

I've also decided that I can't justify having the heating on during the day just for me (when I'm working from home) so I shall be wearing many layers... I suppose I could decamp to the living room and light the fire on really cold days. I wish it was a working fireplace in my study - that would be ideal. Generally speaking though this house tends to retain the heat quite well from a few hours of rads on in the morning and evening and especially on sunny days.
Juju

 

[robgil]

Joce if I can I will help as best I can, period plumbing for me is slowly becoming a speciality. :lol:

Amc if I were you I would be trying to get some rads under my sills, the reason being if you dont already know is the cold air around a window is heavier and drops down in front of the window, the radiator in the room sucks this air across the floor creating a cold draught before heating it and sending it back up into the room.
This cycle then creates a cold spot in front of the window and a cold floor. Single glazing really doesnt help either.

 

[JoceAndChris]

Ooh, for once I'm feeling happy we have rads under the windows after looking at that diagram.

Wasn't that thread called "Winter Draws On", Juju? That might find it. I remember starting it, and there was lots of great advice. I'm feeling much more prepared this year, at last I have the right clothing, and the loft insualtion is happening, and there are thick curtains in lots more places, and I've stuck the sticky draught excluder strips up the door, and plans are afoot to draught-proof the bedroom window. Today I began the process of getting quotes to double glaze our glazed porch, but that's all very much at a thinking-through stage so is unlikely to help this winter, but it's an interesting notion.

I'd light the fire for your solitary working Juju and move there.

 

[AMc]

AMc if I were you I would be trying to get some rads under my sills, the reason being if you dont already know is the cold air around a window is heavier and drops down in front of the window, the radiator in the room sucks this air across the floor creating a cold draught before heating it and sending it back up into the room.
This cycle then creates a cold spot in front of the window and a cold floor. Single glazing really doesnt help either.

There are only three bedrooms which have rads in them any more and only one is in regular use. The rads are in the corner between two walls both with a central window so the convection currents aren't as straightforward as your diagram suggests. Windows are all double glazed and have cills at 40cm and floor length lined curtains so no point really.

@Juju - I also work from home and don't turn the heating on. If you don't close doors then the heat in those rooms will drift upstairs and end up in the roof - warm air rising as it does. If you close the door and use a fan heater with a thermostat it isn't particularly expensive and is much more pleasant. I wear an extra fleece but can't type if my fingers are too cold A 1000W/1KW fan heater running for an hour uses 1 unit of electricity or about 15p. With the stat on low mine runs for 5-10 minutes an hour on a cold day.

 

[robgil]

We had a frost this morning. Good job I'm putting the boiler and rads in this week end, only 18 months late.

 

[Penners]

We had a frost this morning. Good job I'm putting the boiler and rads in this week end

Sounds great, Rob! Should be finished by April?

 

[robgil]

Finished? Now that's something I haven't planned for. My bank manager uses that term much more than I do. :lol:

 

[Penners]

I was referring to the central heating installation, not to the whole project!

I agree that the concept of a period property that is 'finished' is science fiction!

 

[robgil]

Ah , it might take longer than that, I'm doing it in sections when I can afford to., so money dictates how long it will take, which is unforeseeable at the best of times.

 

[sidd]

Just butting in with a little point about radiator convection. The picture and theory is right. Put a radiator by the window to prevent cold air... BUT... If you have curtains covering it, then you are really wasting heat. I have arranged rads and curtains so that where there is a radiator under the window, we used a blind, and the convection goes over the blind, and where we wanted to use curtains, the radiators tended to be on the wall next to the window.

Also, remember that if a stove or open fire is causing convection round one way, and your radiators are pushing air the other way, then it's a mess, and you may be better off warming up from the middle of the building, allowing the outer part of the building to be cooler, which will save energy.