Extractor fan through a window?

Yes but don't cut the glass yourself, drop into a glass shop and pay someone to come out and do it. Looks so simple, a glass cutter on a suction point compass, score the glass and a bit of tapping and voila, ***only*** a minute-long job

Sorry just noticed "double glazed" , don't know about that

You should be able to do that but it will no longer be a sealed unit and how much functionality you lose will be determined by the size of the glass. If is a small unit in a much larger window then it will have little effect on the overall window performance. Since you will have to take out the unit to perform the opening, I would investigate how much it costs having a new sealed unit made up. ,

Without it being sealed won't it just do the same failed DG unit that gets condensation between the two glass panes?

It's possibly toughened, which would make it very difficult to cut. Look into getting a new sealed unit with the vent included.

It's the same problem as getting a cat flat in a sealed unit, and some online suppliers support that:

Theo

You also need to consider the security aspects of doing it. The ducting is not exactly strong and could be pushed aside fairly easily. Window keys are not known for having good security, and IME it seems that a small selection of keys open lots of different window locks.

I thought most such fans were always live, so forcing open the rain cover would start them off. Another consideration is that the glass can act as a sounding board making the fan noise much louder, for anyone concerned about excessive noises.

If it's a sliding window, you could slide it open a bit and fit a bit of plywood into the gap. It's then a simple job to make a hole in the plywood for the fan.

I inherited a kitchen d/g window with an integral fan and I might as well have just had a hole in the window. The fan was really filthy as well, and couldn't be cleaned. When another panel required replacing I got the fan window panel replaced as well. Then later, when I had the kitchen done, the fitter connected the over-oven extractor to a hole in the wall.

Fans are terrible heat leakers. Even with shutters. I have found mine OK to clean though

Ours is for a cooker hood. There is an inline shutter (it does bang a bit on a windy day) and the whole thing doesn't really get dirty, as the hood has a flat panel filter. The filter is all metal and can be cleaned in the dishwasher.

oops! my Forte Agent news reader is going wonky again, with lots of help from me.

Thanks, I'm pretty well put off going through the window. There's a 5 inch gap above the fitted cupboards, which might be big enough to take som ducting from the cooker hood which currently relies on a charcoal filter.