Exhaust fan 4" 260 cfm

I have a 4" 260 cfm exhaust fan running one carbon filter in a 39x39x73 tent. Can I T off same exhaust fan and run ducting with second carbon filter going into a second tent 32x33x60 and both work sufficiently. Ducting lengths in total equal 30 feet.

would be asking a lot from that size of fan. If it were me, I would just splurge for a second fan. Air, much like water, will take the path of least resistance. So if one filter is weaker than the other, it may not work as effectively, add in long ducting, and the one farthest from the fan will barely work (suck air)…

Disclaimer: This is all just theory, as I am far from an expert, and am not certified in anything. So please wait for more expert opinions on the subject before moving forward…

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@Laurap yes you could, but as @Ron330 pointed out you might have one filter suck more or less than the other. If you do divide it, you’ll get half the air flow from the one fan in two tents and this is only theoretical as you could still have variable amounts of flow through one or the other filters. I would suggest getting a larger fan, or two smaller ones. Smaller is sometimes more efficient and you can control the airflow more efficiently.

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Thanks for all info. We were trying to cut down on elec power not blowing breakers.

You’re going to want to get @Countryboyjvd1971 opinion on this. What’s the motivation for trying this over adding another fan? Cost savings, or running out of available power?

Looking at that size of a run, with 2 tents and filters, I would probably want a larger fan. I don’t feel like you’re terribly off though. If you balanced the distance from each tent to fan, installed dampers on each to fine tune, used high flow filters, and avoided unnecessary bends in your ductwork, it would probably be close.

I would ask myself how hard I’m working the fan with the one tent, and how easily are my temps maintained. You’re gonna lose airflow over the run of duct, at every turn in the duct, and by adding the filter. Do you feel like you have that much to spare?

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Ahh, I see you had already answered while I was typing sorry

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Do you have intake fans on both tents?

Reason I ask, if you do, it may be possible to exhaust one tent into the intake of the next, cutting down one 1 fan needed. I have never tried this, but it might work. Anyone ever try something like this before…


In theory with the two tent sizes you could do it @Laurap you have less then 100 cubic feet in each tent I’ll suggest you get dampers as well to help you control the draw on each tent this will allow you to balance out the two tents I would try to split it so you have equal leafhys of ducting going to each filter to y connection
Should work out fine :+1::v: :cowboy_hat_face: CB


Not sure what the cost of materials would be, is possible that running 2 smaller or more efficient fans would be a viable option?

BY drawing from 2 different filters, you will cause evacuation to take 2wice as long, approx.

You can do what you are asking but, use a y if you can find one. Less drag around the corner.

Best recommendation would be to invest in a 6" system. If you cannot; Just be sure to monitor the temps and humidity for a few days and make sure the exhaust system is doing the job, even if slowly, having to run the fans all the time or much longer than when drawing from 1 filter.

Happy sucking…LOL :slight_smile:


We had thought about doing this due to being old house with few circuits. Could I run Romex from another plug to the new tent? I keep on hearing I can’t use extension cords so in theory would this work. Starting a new tent along side of our other one, so all I have so far is shell. Problem is the tent can’t be placed anywhere else.

If you husband is knowledgeable about electrical work Yes can do that as well @Laurap you have to check local codes and make sure your in limits but
Electrical work isn’t for someone who doesn’t know what they are doing tho imo
If you can use Romex run a 12 gauge wire from panel to grow room or area you could put a 20 amp breaker in panel and you have plenty of power available
If you run 10 wire you could use a 30 amp breaker
14 gauge wire 15 amp max breaker
Hope this helps


Thanks, we’ve bought a smaller tent for seedlings and veg but as we’re just setting it up we’re trying to access what we need and what will work . First we thought about using one exhaust and t ing the ducting from both into exhaust but one may get more air removed than other so next was two exhaust but everything is on one wall. Therefore we thought about running Romex from wall plug on side wall for ballast, lights ect.
Limited on where tents can go prefer them together.

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@Laurap Got ya I would run a new outlet over If it was me
Especially since your using hps lights and have a ballast I would run all the lights off the new outlet
And as stated I’d use a 20 amp or better breaker with properly sized wire the
Sizes and amp ratings I gave you are good so you can work with those numbers
And run fans off existing
The fans will only draw a few amps each so I’m sure the existing outlets can handle them
How far away is your panel to tents ?
I saw and posted on exhaust idea as well lol

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Electrical panel only about a foot away from new tent and it’s two feet away from it is big tent

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Omg so easy like 8 foot of wire to do both tent run separate circuits fir each tent if you have the room
I’m running a new line into my grow room as well but it 12 feet away from panel lol
That’s is you best option @Laurap
Can you take a picture of the panel for me
Can you fit extra circuits ?

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Can’t send pic till hubby gets up. Box is in with him. I get home round 4 today. Gotta start cleanup at job but I’m lucky to still have a job to go to after Harvey. Parts of Texas is still being pelted. Houston got 39" in like 3 days. My son had to evacuate.

Hope all is well for you lot over the pond. Harvey and it’s damage even made our news. Alot of sad stories, hope it all works out for you all that’s effected.


No worries @Laurap tag me later then
Glad all are ok after the storm I’ve been watching in amazement at the amount of water you all got down that way :open_mouth:

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We were very lucky. Living on a hill helps a lot. Ended up w/ neighbors & their animals bunk with us but we only had downed trees and fence damage. Not sure if this pic is good enough if not send ya one when I get home.