duct reducers

[Total Head]

The topic has come up in other threads but i can't seem to find an answer. Do duct reducers reduce air flow or increase it? The reflector I want to use has a 6 inch duct and I want to make it a 4 in to exhaust the light. The other hole will just have a regular box fan or something blowing air at the reflector. It's not that I CAN'T use the 6 in, I am just a bit limited on space where I have to make the hole for the ducting to run it out of the closet because I have to make other holes to exchange the air in the closet itself. It seems to me that making the duct smaller might actually increase the airflow by forcing it thru a smaller space, but I;m kind of an idiot about physics. Is this a good idea or should I just shut up and make room for the 6 inches?

 

[FootClan]

The topic has come up in other threads but i can't seem to find an answer. Do duct reducers reduce air flow or increase it? The reflector I want to use has a 6 inch duct and I want to make it a 4 in to exhaust the light. The other hole will just have a regular box fan or something blowing air at the reflector. It's not that I CAN'T use the 6 in, I am just a bit limited on space where I have to make the hole for the ducting to run it out of the closet because I have to make other holes to exchange the air in the closet itself. It seems to me that making the duct smaller might actually increase the airflow by forcing it thru a smaller space, but I;m kind of an idiot about physics. Is this a good idea or should I just shut up and make room for the 6 inches?

I Would go with the 6 inch duct.... when you reduce it to 4 it well be louder and have more friction......id go with 6inch i run 6inch and im reducing it from 8inch fan