[heiditann]

OK, we are doing a DYI install of our HVAC system in our cabin. I had a local HVAC contractor map and do the J loads so I know how large my duct runs need to be and how many CFM's per room and register. However, what I cannot figure out is how I size my register boots. Is there a chart somewhere that tell how many cfm for what size of register?

 

[57TinkerMan]

A real simplified example for you. Data from supplyhouse.com searched for floor registers. I used a 4 x 10 floor register at 100 cfm as an example. In general if you size your supply registers between 500 -700 fpm face velocity and your return grille face velocity at 500 fpm maximum (I prefer less) you should be ok. Don't go crazy using 3 different sizes of floor registers, most homes use one size throughout for visual cleanliness. Your return grille selection is a bit more critical, don't under size them you could have noise issues. There's a lot more to this but keep it simple. Let us know if you have any really big rooms or more questions.

 

[heiditann]

Thank You so much, I was trying to order my register boots and was stressing that my inspector would make me change them all when I was done.