Touch wood, it all seems to work nicely and all of the vents in thehhouse either suck or blow as planned.
There are two huge tubes that lead to the outside and one was blowing out a gale, and the other was sucking like a hoover.
I then spent the morning covering the tubes with insulation, and I would like to see any air try and escape through it now.
I then spent the afternoon taping silver foil around the edges of the windows to make them air tight.
Darren spent the day putting up the cladding on the staircase, and you can see one of the vents from the outside.
Ps, I can imagine what you are thinking, and yes, it is a massive monster.