Really, we need to know more, what are you trying to do? I had intended to bore a hole in my own utility room, however moving from vented, to heat pump drier, removed the need for it.
Any air pumped out, also needs some way for it to be replaced, and this is not as easy as it seems. Many pipes are really heat exchangers
so are both air in and air out, when used with an extractor. Even with only one fan, the idea is the depression in the room will drag air back. The problem I faced with the utility room was there was no return vent, so had to open the window for air to return into the room, so may as well put the pipe through the window of air out.
New double glazing includes a built-in vent, but my double glazing is old.
The whole idea of a vented drier is to draw in dry air. Air in the house is in the main wetter than air from outside, as the colder the air gets, the less moisture it can hold, so since air outside is in the main colder than air inside, we want clearly air from outside. The extractor outside bit
has a vent below it and one ahead, I think the below one is air in and ahead is air out, but with a tumble drier one needs a separate air in.
So until one knows why you want a vent, it is near impossible to answer, the window open did not really work, found the wall going mouldy, how water got in not a clue, there were large landers above the window, so unlikely to rain in.
The heat pump tumble drier uses less energy, but not much less, 2.5 hours at 600 watt v 1.5 hours at 1000 watt is not a big saving, however the utility room and kitchen are now both warmer. The condenser drier would not work, as the utility room is too small, so it would get very hot, and not really dry clothes that well as a result.
