UPVC Windows - Those tiny little external vents

[RogerDIY0]

Can anybody please tell me if those tiny little external vents ( which look like buttons or small one inch long rectangles) which are sometimes fitted to the bottom of UPVC window frames, are really necessary.
I was given some ( in a bag ) with my new "fit yourself" UPVC window and am debating whether they are really necessary. Quite a few professional installations locally are not fitted with them.
I do not wish to drill holes in a lovely UPVC window frame unnecessarily !

Advice welcome please.

 

[noseall]

you mean the drain hole covers?

 

[glassgod3]

if you do mean the face drain covers then the windows should already have the slots routed into to them ready for you to push the covers into,if they are not there and it is a face drain window you will have probs the frame will fill up with water in a while.

 

[Watchmaker]

As previously advised, these are drain covers and not vent covers. Yes, over time, the lip seal, on the outside of the window, will flex and allow moisture to drain into the cavity/slot which the window sits in and it is essential that this moisture can drain away so, if the pre-machined slots are not there, some form of drain hole must be provided. You can, after careful measuring, drill these holes with the D/G panel in situ, if you know that there are packing strips supporting the glass panel but, it is risky and by far, the best way is to remove the panel and make sure that the drilled hole is at the bottom of the frame channel and not anywhere near the bottom location of the DG unit. [/u]

 

[RogerDIY0]

Thanks for reply folks; the UPVC frames were not pre drilled/routed for these but I will proceed as advised.
Another question: The double glazed panels were supplied with adhesive tape/foil along the edges. One company tells me that it is to protect handlers against the sharp edges of the recently cut glass and to remove it before installation, another tells me not to remove it.
Any advice on this one please.