Malc wrote:

If I could tap into this thread for a while. Is is possible to replace
the double glazed unit in uPVC windows. Ours are beginning to show
signs of internal condensation and I'm not sure how to a) remove the
unit from the frame and b) if replacement units are available

Yes, it is (or should be) fairly straighforward. You remove the beads,
measure up, get a replacement unit made, put it in, replace beads.

--
Grunff