On Dec 15, 9:56*am, harry wrote:
On Dec 14, 3:43*pm, Martin Brown
wrote:



On 14/12/2011 15:06, NT wrote:

On Dec 14, 1:49 pm, *wrote:
Does it lose its effectiveness if emulsioned over? This one, though
expensive looks ideal, any experience here please

No. Radiators convect, they dont radiate, and a shiny metal surface
makes no difference to convection or conduction. Its a waste of
kitchen foil.

Actually it makes a fair bit of difference once the temperature of the
radiator is above 50C or so. Convection is still dominant but you can
also feel the thermal radiation in front of most decent radiators.

Reflecting that away from *outer* walls is worthwhile, but far better
with insulation behind so the foil is thermally isolated.

I have seen someone get caught out by an old style linear regulator PSU
they put in a basic folded shiny aluminium case and it got so hot that
it went into thermal shutdown. After painting it black it was 60C.

(in fact any non metallic colour would do as "Black" for thermal IR)

Regards,
Martin Brown

Everything above abolute zero temperature (minus 273.15degC) radiates
energy. if you have two adjacent objects at different temperatures,
they radiate energy at one another until they equalise. Assuming
energy is not being added to them).
The shiney foil delays the process.

Yes, everything radiates, the question is how much. Radiators don't
radiate to a significant extent, meaning the conducted heat output is
very much greater. What's wanted to cut heat loss is insulation, not a
reflector.


NT