Fitting extractor fan vent in the kitchen

[banjodeano]

Hiya Guys, I wish to fit an extractor fan and hood above my cooker, but directly where i want to fit it there is an air vent on the outside wall, i think it just goes into the cavity as there is no vent inside the kitchen.As my house has cavity wall insulation, does that mean the vent would be redundant? and would it be possible to use this vent as an outlet?
Thanks

 

[Doggit]

It's more than likely that there was a vent inside the kitchen as well at some stage. If the outlet from the cooker hood lines up with the vent hole outside, then use a core drill and cut a hole through, then fit a vent tube through the wall, and make good outside. If cold air is going into the cavity, then it'll be losing some of it'd efficiency.

 

[banjodeano]

It's more than likely that there was a vent inside the kitchen as well at some stage. If the outlet from the cooker hood lines up with the vent hole outside, then use a core drill and cut a hole through, then fit a vent tube through the wall, and make good outside. If cold air is going into the cavity, then it'll be losing some of it'd efficiency.

Thanks for taking the time to reply Doggit...
dont some of these vents go into the cavity to vent it? i know that those below floor level go straight through to let air circulate below the floor, but i thought some of these in the walls just vented the cavity, or have i got that completely wrong?
cheers Dean

 

[Doggit]

The cavity is there to provide an air gap, but if the cold air is getting in from outside, then it pretty much ruins the outer wall being there. The air bricks under the floor are to keep the joists from rotting due to a moisture build up, but the cavity should still be sealed around the vent. If you vented moist air and cooking stuff into the cavity, then the cavity will start getting wet over time. You should always put in tubing (angled ever so slightly downwards to the outside) so that any moisture that condenses out goes outside of the property.

 

[banjodeano]

The cavity is there to provide an air gap, but if the cold air is getting in from outside, then it pretty much ruins the outer wall being there. The air bricks under the floor are to keep the joists from rotting due to a moisture build up, but the cavity should still be sealed around the vent. If you vented moist air and cooking stuff into the cavity, then the cavity will start getting wet over time. You should always put in tubing (angled ever so slightly downwards to the outside) so that any moisture that condenses out goes outside of the property.

Cheers Doggit