expanding foam as CH pipe insulation?

Sounds messy and expensive. Why not use the old fashioned felt lagging? Just wind it round all 4 instead of one.

NT

or use this spiral wrap from screwfix. It is silver bubble wrap and is designed exactly for your purpose.

That'll be UNexpanded polystyrene then.

-- Mike W

Sounds a very sound way to proceed to me.

I'd say that its probably BETTER than foam sleeves.

I can just picture your shed or wherever you keep stuff.

'We saw Foam, lots of foam, lots of foam...'

Thanks for all suggestions. Just curious if the expanding foam gas same insulating properties per volume as pipe insulatoin? peter

Products typically have a rating in watts per hour of energy transmission. But PU foam-in-a-tin can not because it depends how it is used. The user affects how aereated the foam is. However it will be roughly comparable to any PU foam product such as kingspan, look on there web site. Err on the lower side since their facilities obviously allow the best possible values to be achieved.

Thanks Mike

Do you think that the claim that spiral wrap from screwfix is an equivalent to 33mm polystyrene not possible?

rafal

I think whatever dimension that 33mm is supposed to apply to it is unlikely. If it refers to the usual wall thickness then it is extremely unbelievable. B.Reg for climaflex insulation rating works out to be 25mm. Expanded Polystyrene is going to be very similar if not better thermal efficiency. Foil backing may be effective but I don't believe it beats depth of something decent.

-- Mike W

In article , VisionSet writes

Agreed, the claims are complete pish.

On Sun, 24 Sep 2006 22:01:16 GMT, a particular chimpanzee named "VisionSet" randomly hit the keyboard and produced:

I was sceptical too, but it appears to be correct. The R-value of Alreflex (the nearest equivalent I could think of) with no cavity either side is 0.15m2K/W; the R-value with cavity both sides is 1.56, so the R-value with one side exposed must be 0.93. Multiply that figure by the conductivity of polystyrene (0.037W/mK) and the equivalent thickness is 34mm so they're not far off.

On Sat, 30 Sep 2006 23:29:09 +0100, a particular chimpanzee named Tony Bryer randomly hit the keyboard and produced:

equivalent to 200mm of rockwool. Alreflex is bubble-wrap sprayed silver. The R-value includes a value for the material as well as increased resistances of the air either side as it has a higher emissivity (or is it lower?, it's late & I can't remember). The values I quoted were taken from the BBA certificate for it, so if you can't believe them, who can you believe?!

In article , Hugo Nebula writes

Although the BRE report refers to multilayer I believe that the failings pointed out apply to all products that (over) rely on reduction in radiation for their 'enhanced' properties.

The easy flaws to spot are:

1. They rely on a carefully controlled air gap to meet their stated performance.
2. The gap must be still air or heat will lost by conduction to the moving air (forced convection if you like), so no draughts and no ventilated roof or cavity.
3. The gap has an optimum width, too great and there is room to create a convection loop giving more heat loss.
4. The reduced radiation relies on clean reflective outer surface, get it dirty or dusty and there goes the radiation benefit resulting in more heat loss.
5. The reflective surface may lose its shine with age resulting in more heat loss.

To stand a chance of this product getting close to its design claims you have to install it in an unrealistically perfect environment. In contrast, trapped air systems (foams, rockwool or whatever) can achieve high performance with a lot less attention to detail.

The document I cited relates back to results produced by TRADA: "if you can't believe them, who can you believe?!"

On Sun, 01 Oct 2006 22:10:14 +0100, a particular chimpanzee named Tony Bryer randomly hit the keyboard and produced:

The problem with the TRADA document is that they don't have the accreditation to test for insulation values; so one couldn't believe them WRT insulation.