Hey everyone! I'm in the process of swapping out my recirculation filter for my kitchen range hood, which I really love. My landlord gave me the green light to replace the existing 3.5" duct pipe in the wall. I've seen online that a pipe size of 7-8 inches is recommended for appliances that pull 800-900 CFM. However, here's the catch: the space available is only 6.8 inches wide from the wall to the first stud. Can I make do with a 6" duct, or would it be okay to install a flexible 7" duct and squeeze it into the available space? I'm looking for any advice or insights you might have!
3 Answers
Check the installation instructions that came with your range hood. They usually have precise details on how much flexibility you can have with duct sizes and how different fittings influence airflow. You could also consider having a carpenter help you out by adding a stud alongside the existing one to make that tiny adjustment needed for a 7" duct.
Since the connection at the top of your range hood is 7 inches, you could technically use a reducer from 7" to 6", but be careful about introducing too much pressure drop. It might affect performance. If you go for it, just know it won't flow as well as you'd like.
To really get the best performance from your range hood, it's important to stick to the duct size recommended by the manufacturer. For anything over 400 CFM, you're also going to need make-up air to ensure proper ventilation.