Reentrant wrote:
Our double-glazing is about 16 years old, and in the last 6 months three
units have failed with condensation inside. All the failed units are
south-facing - presumably the more extreme heating cycle weakens the seal
eventually.

3) Can I replace the units myself like for like, or does a FENSA bod have to
do do (or approve) the work?

Not too difficult, on my older panes I removed the rubber seal from the
inside which then allowed the outside seals to pop out easily.

Took the panes out to measure, I had leaded glass which made it more
difficult.

Geoff Lane