Ventalation for pellet burner, kitchen and bathroom

I dont hnow what building regulations apply in spain, in the uk you would need mechanical ventilation for the kitchen and bathroom, for the room the wood burner was housed you would require permanent ventilation and a carbon minoxide alarm

If the vents in the kitchen and bathroom are purely for ventialation then why do you need them going through the roof? Normally when I fit vents they go through the wall venting to the outside. I take it there is a reason why you want to vent through the roof with a powered vent??

The pellet burner would also need a free vented area equvalent to 75 square centimeters which works out at a hole through the wall of 127mm.

I would be happy to quote but you are a bit too far for me as I live near the Mar Menor, Los Alcazares. Ideally  you will need somebody with a diamond core drill rig which will go through just about anything. Hoe thick are you walls?

If you are talking about the flue from the pellet burner, then it would have to go through the wall and extend upwards above your roof line. If it is just for room ventilation which you would need in addition to the flue then it would need to be a 127mm hole through the wall which would just provide ventilation. For the bathroom and kitchen then a natural draught vent would be fine A natural draught vent is just a hole in the wall.

The pellet burner is just a different type of wood burner so would need a flue which extends vetically and ideally should go above the top of you roof. When you instal any type of wood burner what you are in fact doing is trying to equalise the pressure in your house with the pressure outside. If the pressure outside is greater then the wood burner would not be able to get the products of combustion, (the smoke) out.