8" fan cooling 6" hoods?

[Cutty]

Setting up the new and I have on hand 3x 1000 that I will run in series. I have cooled 2 before with a 6" and all was fine.
This time I am going to have some longer runs and a hard 90° before I dump the exhaust out. The 90° will be right after the fan, runs and hoods preceding it.

I have thought about amping up my fan to an 8". Due to the CFM loss of the runs and turns I am thinking I will come close to where that 6" was with short, straight runs.

What does the community think?

6" Vortex 450 CFM
8" Vortex 747 CFM

 

[whiskeytango420]

I run 6 1ks, and they are in 2 rows of 3. I only have a 6in on each row, without the 90deg bend though...In cool tubes too....Are your hoods sealed?
If you wanna go to an 8in, just go to grow de pot and get a 6 to 8in flange.

good vibes

 

[Cutty]

Yes, sealed hoods. May or may not light the burner this time, but that's immaterial to this discussion.
I thought that I would stay with the 6" ducts all the way to the fan and then open it up into an 8" and dump the hot in a cool place.

Should I size up the ducting right after the last hood?

Is there a formula for determining how many 1K's can be cooled by xxxCFM. I know there is the variable of ambient going in but just a loose guideline?

I ask this because 3 is the starting point. I have more hoods, but only 3 1K ballasts on hand. Planning on vertical hanging 2 600s in the space as well. Have a/c.

 

[whiskeytango420]

IF i was switching to an 8in fan, I would use 6in duct all the way up to the flange I was talking about thats connected to the fan...just my :twocents: though

good vibes

 

[Greenlife1]

I agree with Whiskey. I am running 2 1000's atm, but have 3 hooked in series as you are saying. I would definalty go with the 8" I have yeild master 2 hoods, and hook the adapter right to the fan. The only heat that I get is a little radiant. I can hold my hand an inch form the glass and not feel much at all.

 

[MTRUM75]

Does anybody know if there would be any benefit to running the 8" duct as far as possible then switching to the 6" duct? Instead of stepping down directly after the fan.