Stepping down ductwork?

Hi All,

Love the forum first of all, been a great source of inspiration.

I'm setting up in a small darkroom 3' x 3' x 5.3 (height)

I have a 4" vortex inline fan but a 8" AC sealed reflector/hood.

Things are tight spacewise in there with the size of the reflector. So I've currently got the fan outside of the darkroom but Boy! is it loud! Will hanging the fan inside the room cut down on the noise by a significant amount?

I also have a 4" carbon filter. Any tips on stepping down the duct size? Or should I just buy 8" ducting and clamp it down until it fits?

I bought a couple of reducers from home depot (8" to 6" and then 6" down to 4") but they are quite large but they will not fit on the reflector. Things are just too tight with that huge reflector

Any tips or suggestions would be welcomed. I'll try to get some photos on later today when I'm back home.

This is going to be hard to do. No clamping down 8" ducting will not work.
What size light are you using?
Is there any way to put an elbow (90) in there? Typically i am against this, but in this case it may be ness.
I believe that it may be possible to source a 8"-4" reducer, but not positive. You may consider a piece of sheet metal, bent into aprox 9" circle on one end, 3.5" on the other side. Now cut length wise down the metal a little ways to make the ends flat and not taper, now tape everything together and it should work. Going to cut yourself at least once making this if you don't wear gloves though.
I am subscribed so when you post pics i will see what i can do to help.

i put fan inside my grow tent still loud as hell.
unless u go to custom sheet metal shop u wont find any reducers over 2 inch in difference

TruenoAE86coupe said:

This is going to be hard to do. No clamping down 8" ducting will not work.
What size light are you using?
Is there any way to put an elbow (90) in there? Typically i am against this, but in this case it may be ness.
I believe that it may be possible to source a 8"-4" reducer, but not positive. You may consider a piece of sheet metal, bent into aprox 9" circle on one end, 3.5" on the other side. Now cut length wise down the metal a little ways to make the ends flat and not taper, now tape everything together and it should work. Going to cut yourself at least once making this if you don't wear gloves though.
I am subscribed so when you post pics i will see what i can do to help.

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@Trueno: I'm running a 400w MH right now. I like your idea about using the sheet metal. I have some that I could try this out. But I tend to be all thumbs and would likely cut myself even wearing gloves!

I'm posting the photos and as you can see things are so damn tight in there with that huge reflector I hardly have 3 inches on each side. Total area is square 3 x 3. Sorry for the bad photos my 3 year old destroyed my digi-cam for the second time this year and these are taken with a 3 year old BB. I posted a few pictures of my children just because I'm a proud pappa

How vital is it to cool down that reflector? I realize it extends the life of the bulb, but as long as I'm exhausting the excess heat, is is that big of a deal?

If I avoided this issue, this would allow me to attach my carbon filter easily directly to the fan inline. I don't have too many openings on this room. I may try to vent out the back but it is a smaller opening than the one where the duct is going through the roof currently. I realize that this 90 degree bend right at the fan is not ideal.

@Rjstoner. yup I moved it from mounted outside the tent to inside as you can see... no real noticeable different in noise level. ... hmmm.. wife isn't going to like this.

What if you were to just stick the fan to the side of the hood? obviously small, but it looks like it could work. Maybe run an 8" duct from outside the tent to one side of the hood, then use the fan to vent the hood. You will probably need a second fan to keep fresh air in the tent.
Noise issue: insulated ducting helps a lot with this, the actual air movement will still make noise, but the fan itself will be quieted.

90 degree bend is obviously not ideal but I actually have a room in a small space with one. It def doesnt maximize efficiency but I don't notice a diff. The fact that u use the filter makes me think u r concerned wig smells, so if u stop venting u will have that issue. I have noticed the filter acts as a silencer of sorts when directly connected cutting down a lot of sound. There r diy silencers as well I'm partial to the kind where u use a platic tote and cut out the sides cause I have tons of totes. Just make sure you use a solid noise baffling material and not something like fiberglass insulation that will bllow around particles.

Thanks for the ideas... I'll play around with it and post my results.. hopefully something that looks decent and does the job.

I like your idea of just hanging the fan by the side of the hood. I could then hook up my carbon filter on the other side of the hood but with some ugly bends. I have these 8" x 6" reducers and I'm going to pick up a 5" x 4" reducer to connect the carbon filter



Yeah I guess I'll have to splurge on the insulated ducting. It's like $35.00 for a 16 foot run or something like that at home depot

@roidrage. Thanks I'll have to check out some DIY Silencers I've spent enough on this setup already and Christmas is just around the corner, so the idea of DIY is getting more and more attractive to me.

It all looks new is it. #1 go back to the hydro store and exchange it, most shops will help you out like B&B, the Emporium. #2 call Boone plumbing @ 746-7070 ask them if they have such a thing as an 8 to 4, #3 go buy a cheap gull wing 45$ and keep the fan inside the tent. #4 pm me and I will swap you a 4" for the 8" or give you a gull wing or leave it somewhere for you to pick up. I got kids too.

short term DIY get a cardboard box put the fan in it with some holes punched below and above the 4" exit holes, need some air movement in the box to cool the fan, just a few. and put a sleeping bag over the exposed 3 sides.

You only have 45 sq feet so you don't need to run the fan at full speed. it should be around 170 CFM that will change the air in your tent every 30 seconds or pull it inside out LOL. You can buy a controller but it has to be made for the amp rating of your fan. The ones you see are all meant for smaller fans and will damage your fan. Don't skimp!

Got to B&B hydro and get a reducer for your filter they have a bunch in stock.

peace and welcome to the hood I'm around the corner.

cap the hood and cut a 4 inch hole in the cap. looks like you have room for a 4 inch elbow in the tent.What wattage is that? reducing to 4 inch is certainly gonna restrict things, it may not move enough air.

woodsmaneh! said:

It all looks new is it. #1 go back to the hydro store and exchange it, most shops will help you out like B&B, the Emporium. #2 call Boone plumbing @ 746-7070 ask them if they have such a thing as an 8 to 4, #3 go buy a cheap gull wing 45$ and keep the fan inside the tent. #4 pm me and I will swap you a 4" for the 8" or give you a gull wing or leave it somewhere for you to pick up. I got kids too.

short term DIY get a cardboard box put the fan in it with some holes punched below and above the 4" exit holes, need some air movement in the box to cool the fan, just a few. and put a sleeping bag over the exposed 3 sides.

You only have 45 sq feet so you don't need to run the fan at full speed. it should be around 170 CFM that will change the air in your tent every 30 seconds or pull it inside out LOL. You can buy a controller but it has to be made for the amp rating of your fan. The ones you see are all meant for smaller fans and will damage your fan. Don't skimp!

Got to B&B hydro and get a reducer for your filter they have a bunch in stock.

peace and welcome to the hood I'm around the corner.

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Wow Woodsmaneh. that's awesome that you are in Ottawa! I've been lurking on the boards for a while and love your posts. I even journaled one of them.. don't know if that is kosher here or not I just wanted to save it for future reference

I went to the emporium to get my set up. found them really helpful, especially Mike. I'm in the West-end-ish (Westboro)

I don't even know what a gull wing is. I'll do some searching on the forums to find out.

I'll check out B&B on woodward and see if I can get a controller for my fan, You're right its rated at 177 CFM and my tent area is approx 50 CF

The hood is not new however. I bought it used.. a 400w lumatek ballast and 4 lights (2 MH and 2 HPS) + the AC hood and a 4 x 3 thick tray for $200 from some guy in Kanata. so that's why I'd like to make it work if possible. It seems to stay nice and cool almost right up to the glass compared to my open reflector that I had running with my 250W setup

If you had any use for the tray I'd be willing to give it to you. My room is 3 x 3 so its completely useless to me.

dbkick said:

cap the hood and cut a 4 inch hole in the cap. looks like you have room for a 4 inch elbow in the tent.What wattage is that? reducing to 4 inch is certainly gonna restrict things, it may not move enough air.

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Haha I like it.. so simple it should work.. again I think with the wattage of the setup (400W) a 4 inch fan pulling air across the bulb should keep it nice and cool.

Thanks for the offer but been doing this since christ was a cowboy and have collected all kinds of growing stuff so have a few old ebb and flow tables around. I used EPDM (rubber tube material (ethylene propylene diene monomer)) here is a pic

Mikes a great guy and the owner Dennis is a friend of mine, and Mike over at B&B is also a buddy. I know the guys out east at Bright Light also. Been doing this a long time. If you have any issues fell free to pm me. I help MMP set up there systems and teach them to grow depending on their mobility issues. No I'm not a saint just an old Cowboy grower that likes to help.

Woodsmaneh: Went to B&B for the first time today. They were really helpful. They actually sold an 8 X 4 reducer. I'll post pics of my setup once i have it all installed. I"m going to run 8" duct work from my reflector to my fan and my carbon filter.. Bought a fan controller too so now things are nice and quiet and everyone is very happy.

Thanks to everyone who contributed and for their ideas. I'll be sure to post photos of the setup once it is complete.

Yup fingered they would, if it was the young lad that's the owners son. Bill is the old school looking guy. Glad you got it sorted out. Happy growing

Well the 8 x 4 reducers from B and B here in Ottawa were a godsend. I finally got my fan in line and just one 90 degree bend at the reflector

Like Red Green I believe that Tuck Tape can fix everything...

Here are the photos. I'll be doing the intake/carbon filter side once I start to get some bad smells. (Other than from the Marine food)



Thanks again to all who helped out with their suggestions.

ooooo pretty!
No really looks good!

Had the same problem and had to hang my light corner to corner to barely get ducting attached. Looks goofy, but I got everything in there. Also, before you spend the $$$$, I got that duct insulation and it really doesn't do anything for noise reduction (at least for me). My unit make no noise except the sound of air whooshing out at the end. Working on a muffler for that. Interested to see how you work it out !! Looks great though