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How do you connect pc fans to duct?

Derka

Derka

Member
I've hit a snag of only having some 150 cfm 120mm fans to use to pull air out of the carbon filter/duct and blow out of the cabinet, however I am drawing a complete blank on how to effectively connect them to the 4" duct. I believe I saw something about using 4" shower flanges as the transition piece, however a 120mm fan is a little bit over 5 inches.

I attempted a search, however pc fans, 120mm fan, ducting, and adapter are all very commonly used terms.

Any ideas? Suggestions? Links?

Thank you.
 
A

ak-51

That is something you will probably have to make yourself. Get the male part that a 4" flexible duct would fit over, build a 5" box onto that and stick the fan on the other end.

I am going to recommend against any of that though. You mentioned a carbon scrubber and I don't think your little PC fan will have quite enough power to pull sufficiently through that. Maybe if you made your own small carbon scrubber then it would be ok, but a normal sized one is probably too big for that fan. I used some of these for circulation and also a very small home-made carbon scrubber that I made a long time ago. I'm not sure if it actually did anything since there was so little carbon. They were great for circulation except that they are extremely loud. I think I remember reading a review somewhere that said when a kid plugged them into his computer his parents thought he was vacuuming! I eventually got a fan-speed controller to tone them down a bit. Like I said, they were great for moving air but I am not sure if they had the kind of torque necessary to move air when there is as much resistance as is present in a duct and filter setup.

tl;dr: They should be sufficient for ventilating any cabinet-sized grow but don't expect them to do any heavy lifting.
 
someotherguy

someotherguy

Active member
Veteran
high man, below i've listed a couple links for you to check out, the first is to a builder who is using a toilet flange to mount his pc fan to his scrubber, a DIY project.

https://www.icmag.com/ic/showthread.php?t=199899Sergeant's got a brand new cab

and here is a pic to illustrate how he did it although there are many more pics in his thread so check it out.
picture.php


now here is a link to a nifty little DIY scrubber that won't overpower a pc fan.

DIY Micro Carbon Filter; Cheap, Easy and Quick.

and a pic to illustrate
41938msc6.JPG


hope this helps, SOG
 
Derka

Derka

Member
re

re

Thank you SoG/AK

These aren't your typical crap junk 120mm fans. Delta 150 cfm, they pull a little over 1 amp. The carbon filter is massively overbuilt for the cabinet, 4 inch core, 6 in shell that is 24 inches long. The cabinet that it was made for is 36x18x60.

My biggest issue is that it is a metal cabinet, the top shelf only has ~ 7 inches of clearance, and I need to keep that shelf relatively intact as I'm hanging my lights off it. I don't know of any decently powered fans that would fit in ~ 7 inches of headspace.. hence relying on some of the most powerful pc fan I could find... and the issue of how to connect it to the carbon filter and vent it out without any bends.

The other option of course is a stanley blower mod, but I would have to run ducting out of the cabinet to utilize that solution.
 
S

sm0k4

Delta is pretty good when it comes to fans. Love those things. You should be fine.

Here is my DIY scrubber from an ~3" wide wire desk cup I found at Staples. I think I have too much carbon in there, but I haven't tested it yet to get it right. I need to get my micro cab built this weekend and test it out. You just have to adapt the carbon scrubber to the fan and keep it airtight plus make it easy to refill in the future. The green fan might need to be replaced by a Dayton if this one proves to be too weak. Just tried to use what I had around in spare parts bins.

 
Derka

Derka

Member
re

re

Thank you smok4!

The toilet flange looks interesting, its the transition from 120mm fan to 4 inch duct that is troubling. I do like the small box idea, and another mate of mine recommended using a 6 inch square drain.. Just mount the fan to the drain and attach the duct to the 4 inch sewer pipe male connection.

I've got to get this resolved so I can finish my cabinet, that or go ahead and use the stanley blower.
 
DiscoBiscuit

DiscoBiscuit

weed fiend
Veteran
Nice fans and scrubber idea. This tip would work better with 5" duct. You'll get a bit of back pressure when going from a 5" fan to a 4" duct, not as efficient.

Flex duct? If so, you can use scissors and wire cutter to cut the fan end of the duct in 4 places (equal distance apart.) Only make the cuts as deep as the chassis thickness.

Don't laugh, splay the modified duct over the fan chassis, carefully and neatly duct tape the bad boy. Or you could use a radiator clamp or large cable tie and duct tape the rest.

Ok, go ahead and laugh. The only down side would be a bulb too close to the duct tape. Not that it's a fire hazard (the duct tape is more durable than vinyl flex duct, assuming that's what you're using.)
 
Derka

Derka

Member
Thank you DiscoBiscuit!

This was exactly what I was looking for, and it eliminates an extra 15 dollar piece from the jigsaw puzzle that this cabinet is becoming.

Gotta love the ICMAG community!
 
StealthDragon

StealthDragon

Recovering UO addict.
Veteran
I use a container kinda like this:
jt6150.jpg


found it at walmart by the food storage stuffs. .. still have to use some duct tape though ;) a 2liter bottle can be made to work also if you're low on $'s
 
pearlemae

pearlemae

May your race always be in your favor
Veteran
I use a 120mm fan in a 4 in duct, Get a 4 inch to 6 inch adapter I got mine at Lowes in the duct section. Set your fan on the 6 inch end, mark each side of where the corners over lap the duct. with tin snips cut and bend each marked spot on the duct. Bend the cut areas outward and fit the fan into the cut areas,bend the flanges back over the corners and shazaam a fan in 4 in duct. You can sort of see the duct in the back of the pic the fan is where the little blue led is. the light doesn't go back to the flower room cause there's a 4 lb carbon scrubber I built on the other end. If need be I'll take a better pic if needed.Hope this helped:plant grow::smokeit::bongsmi:
 
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pearlemae

pearlemae

May your race always be in your favor
Veteran
Better picture I used a heavey duty double sided tape to halo it all to the inside wall. It's been a year and still sticking. on the other end is the carbon scrubber 4 lb of carbon from the fish store. The fan needs to be dusted I never looked at it, it run 24/7 for the past year.
 
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supermanlives

supermanlives

Active member
Veteran
you can buy an adaptor designed for dryer machines its square and connects a box to 4 inch round. home depot has em
 
DiscoBiscuit

DiscoBiscuit

weed fiend
Veteran
pearlemae said:
The fan needs to be dusted I never looked at it, it run 24/7 for the past year.
Click to expand...

Looks like mine, more color than accumulation. Looks like you're using an intake filter(s).

Here's what I did with homemade pvc collars and "used" dryer sheets. It's not hypo allergenic, lol. But used dryer sheets won't tax exhaust fans like micro-weave hepa filters





Last pic is the light trap made from a raised panel, 1" smaller than the footprint (L x W)
 
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