My family is busy assembling an IKEA kitchen that should have a carbon filter fan above the stove in the vacation house. According to the assembly instructions, an aluminum vent pipe (150mm in diameter) should go straight up through a hole in the top/ceiling of the Metod cabinet where the fan is mounted. That would be great IF the ceiling wasn't as close as 7-8 cm above the aforementioned pipe opening/the top of the Metod cabinet (see pictures below). We don't have any installed ventilation in the kitchen unless you open the kitchen door (but a heat pump will be installed nearby if that helps?) and the house is otherwise an old solid 60s construction in wood with natural ventilation via a chimney two rooms away from the kitchen.
The fan and the pipe
Where the pipe exits
To the left of the stove - make a hole in the house wall here and direct the exhaust there?
Do you, dear forum experts, have any suggestions on:
1. How can I best protect the interior ceiling from humid air from the stove fan? Should I go for a 90-degree bend from a round to a rectangular air duct that leads the exhaust back into the room through something not too ugly like a grille? Should I make a hole in the ceiling and direct the air up to the attic and further out? Or is it more suitable to direct it to an opening I make in the house wall, similar to how you make holes in the wall for bathroom exhaust fans (skeptics mention the risk of mold and growth on the house wall where it exits through the house wall). Do extensions of the pipe need to be insulated in any way (like against fire)?
2. Given the natural ventilation through the chimney two rooms away from the kitchen, should we install some kind of bathroom fan in the kitchen to reduce the humidity level during and after cooking, or can we expect a heat pump to keep the humidity in check sufficiently? It's just a vacation home kitchen that will be used for longer periods in the summer and otherwise some weekends in the fall/winter, so perhaps the wear on the house is minimal and the humidity in the kitchen won't cause much damage? 🤷♂️ Is less more?
Since it is a carbon filter fan, the air should not be led out but remain in the kitchen. If you create an outlet through the façade, a regular fan without a carbon filter is best.
For the carbon filter fan, it's perfectly fine for the air to come out in a 7-8 cm high space that is not completely enclosed. However, the surfaces may not look so nice over time. A ceiling connection with a grille works.
According to Boverket, there should be exhaust air near the stove/hob, a so-called imkanal.
An air/air heat pump does not affect ventilation because it only circulates the air already inside.
If you lead a fan duct or an imkanal out through the façade, you probably need to make a building notification to the municipality, and the chimney sweep must approve it afterward due to the fire safety requirements associated with it; you don't want the façade to catch fire immediately if something on the hob ignites. I don't remember the details, but it's something like having either a fire damper on the inside or protecting the façade with an overhang, and if it's a wooden façade, you attach a metal sheet; the outlet must not be too close to an eaves, and the air sent out must not be drawn back in as fresh air through a window/inlet vent.
