I wanted to paint a radiator (already having been painted by a
previous owner) with the same paint used for the walls. It is Dulux
Rich Matt emulsion but says on the tin not for radiators!

Radiators need special paint because of the heat. These paints are usually
solvent based gloss paints. However, I believe that Dulux Trade Aquatech is
a water based paint suitable for radiator application that might come in the
same colour as your emulsion, if it is a standard colour. Being water based,
it won't discolour with time. It won't be matt, however, but won't be high
gloss either, as it is water based. You may need to find a "Dulux Decorator
Centre" to get hold of it. They are like builder's merchants for Dulux and
Glidden paint.

Christian.