Brick up old ventilation duct for kitchen fan

[r91]

Hi, I'm in the process of making a new hole (marked in blue) for the ventilation duct for the kitchen hood since we will have the stove on the short side. I plan to fill in the old hole. What is the best way to do it?
I have a few old bricks left, can I use them and mortar to fill in the hole?

 

[Plupp 405730]

Yes, you can use your old bricks, take mortar C so it becomes a bit workable since it's an old masonry...