rpgs rock dvds has brought this to us :
A-ha! No, you're correct. That's all I want to do. The glass is
10.8mm thick, and that's perfect - just what I need. The problem is
that the height of the glass (848mm) is fractionally too tall. If I
could reduce this height dimension to 847mm, it would then fit snugly
inside the inner window recess area.

Problem solved perhaps? I'll ring the glazing shop tomorrow morning,
and report back with their answer+price.
Thanks.

Are you sure the noise is air-borne? A/C's are often mounted on outside
walls and the vibration could be travelling through the wall, rather
that noise through the window.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk