6" fan run through 4" duct

[joewig1980]

I'm running a 400 watt in a 3x3x8 room. I need to suck air through a filter and exhaust the room through several bends. The 4" fans are just not powerful enough, plus I already have 4" ducting in place. Will 4" be big enough to draw the heat away from a 400 watt light? I'd be running a 400 CFM 6" fan capped down to 4".

[GaGrown]

Joe,
You really should use a reducer.. That way the flow is even.Try to get some of the bends out of your flex and add the reducer.. Should be fine,though!

Ga...

[KarolinaKronic]

Just replace the ducting and keep as many elbows out as possible. Your exhaust should not look like some fucky ass screensaver. Also, you mentioned a filter. If the filter is 4 inches, you are going to wear it out quickly. I would suggest perhaps cleaning the air with the 4 inch fan and exhausting with the 6. More electricity but both jobs get done.