Question about Changes in Ducting Width

Hey guys,

I'm looking to hear from anyone who has experience with downsizing their exhaust lines...for example, if your hood is 8" wide but your vent is only 4" wide, couldn't the narrowing channel possibly create a jam and slow the flow of the air?

If so, what solutions have you found?

You'll pull the amount a 4" line would.

So would it be better to have a 4" fan pulling out of the bigger duct, or a 8" fan pushing into the smaller duct?

newcastle543 said:

So would it be better to have a 4" fan pulling out of the bigger duct, or a 8" fan pushing into the smaller duct?

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As I am Learning on RIU, just as you, My logic and reasoning would suggest 8" fan into 4" duct . It seems that U would get more flow, higher pressure. lol i'm keeping an eye on this one!

hititorforgetit said:

As I am Learning on RIU, just as you, My logic and reasoning would suggest 8" fan into 4" duct . It seems that U would get more flow, higher pressure. lol i'm keeping an eye on this one!

Click to expand...

See I was thinking the opposite. To avoid putting pressure on the exhaust line, wouldn't a smaller fan pulling from the bigger duct and then blowing straight out be better?...but what do I know, I'm still trying to figure out if I should blow air across the light or suck air out of it...

It looks like there is going to be alot of learning as I go along, which only wastes time and money.