Duct Splitters???

I was wondering if anyone has tried using a duct splitter kind of looks like a "Y" to pull air with a 4" 160 cfm inline fan (or any size)? I was at lowes today and saw this and started thinking.....

I currently go from filter to hood to fan and exhaust out into attic. If I could split that and have one duct pulling from filter the other ducted pulling outside air (cooler room air) then through hood would it be running cooler air through hood and still filter and pull hot air out with just one inline fan?

My thinking is I would lose a lot of pressure or cfm doing that...and it might not work very well? Wondering if anyone has tried this?

the air pull will go to path of lease restaints.....u might pull a little from the filter but it will mostly come from the outside line since it does not need energy to pull it to the filtering unit

when working with air it is alot easier to see it as water most of the same princples are in effect in flow eddies wind paths


those spliters those make good access to inline carbon filters or allowing u to add a Co2 /Ozone ........use to be able to take a coffee lid put it onside with out the ducting tape down and then poke a hole for the co2 line in for the intake ......do the same for the exhust with ozone

your best bet is to get 2 inline fans one only for intake one for exhust the exhust has the filter so the withdrawl is less then the intake is pushing in so u get a possitive pressure on it ....cut off the intake and u will get a negtive ..........u could use one of those lower flaps lift it up in the tent and u got your air flow cooler air

cold air sinks ........hot air raises

Thanks that helps a lot. Right now I go filter in closet to hood to fan and out to attic. Pulling 80-84 degree air through hood. I maintain temps around 80 but hoping to get it down even more. I do have lots of negative pressure. I created a semi sealed room. Lol. By putting up some panda paper and zipper to seal it up and avoid light leaks. I cut a 4" hole at the bottom and ran some ducting but still getting negative pressure so was thinking of going bigger 6" and leaving it passive. But maybe I do need another fan just trying not to create more noise. I guess my second question which is obvious is the ambient temps in the main room are going to control my temps as well. If its 80 in that room then in my grow right now it would a few degrees warmer.

justugh said:

the air pull will go to path of lease restaints.....u might pull a little from the filter but it will mostly come from the outside line since it does not need energy to pull it to the filtering unit

when working with air it is alot easier to see it as water most of the same princples are in effect in flow eddies wind paths


those spliters those make good access to inline carbon filters or allowing u to add a Co2 /Ozone ........use to be able to take a coffee lid put it onside with out the ducting tape down and then poke a hole for the co2 line in for the intake ......do the same for the exhust with ozone

your best bet is to get 2 inline fans one only for intake one for exhust the exhust has the filter so the withdrawl is less then the intake is pushing in so u get a possitive pressure on it ....cut off the intake and u will get a negtive ..........u could use one of those lower flaps lift it up in the tent and u got your air flow cooler air

cold air sinks ........hot air raises

Click to expand...

Please do not give Info you think you know, Air moves nothing like water ,Air is moved by Static pressure,water is moved by PSI ,

what you are reffering to is what is commonly called a T Y fitting. up your size duct from the fan out to your attic to 6'' round ,the you can use a T Y fitting on the intake side, the way you have it hooked up as of now you are only pulling at best 80 cfm.

people think just because the fan inlet and out let are made in a certain size that is the rite size duct work to be attached , Nope

you cant fit 10lbs a shit in a 5lb bag , and dont tell me the guy at the hydro store said ,he moves product NOT AIR. I move air for a living.

4 inch duct can only handle 80 cfm. the fans are made to keep the stadic pressure constant , from ther you must properly transition the duct work to to get the full spetrum of CFM the fan put out.

Sorry for the rant .and no disrespect just tryin to edumacate

jrainman said:

Please do not give Info you think you know, Air moves nothing like water ,Air is moved by Static pressure,water is moved by PSI ,

what you are reffering to is what is commonly called a T Y fitting. up your size duct from the fan out to your attic to 6'' round ,the you can use a T Y fitting on the intake side, the way you have it hooked up as of now you are only pulling at best 80 cfm.

people think just because the fan inlet and out let are made in a certain size that is the rite size duct work to be attached , Nope

you cant fit 10lbs a shit in a 5lb bag , and dont tell me the guy at the hydro store said ,he moves product NOT AIR. I move air for a living.

4 inch duct can only handle 80 cfm. the fans are made to keep the stadic pressure constant , from ther you must properly transition the duct work to to get the full spetrum of CFM the fan put out.

Sorry for the rant .and no disrespect just tryin to edumacate

Click to expand...

how many times have u sat and watched the smoke move tho the air .................try it watch........then try with water and food coloring ..............before u yell at someone think about what they are saying my ...........areodynamtics and hydrodynamtics are very simlar and have many over lapping math one applies to the other use the same ..............i am not making the wind i am using it like a flow in a stream of water it hits at this angle it spreads it hits at this angle it starts a little votex

I have heard the water and air analogy before. Either way I would assume it flows to the path of least resistance which makes sense. So if I am stuck using my 4" inline fan (will upgrade light and hood one day and have 6" fan) I should hook up a 4" to 6" adapter and run the larger ducting into attic? That would give me more cfm? Would that also decrease noise? I would still not want to use a T Y fitting to try and pull both air from my filter and the other duct to outside of closet for fresh air. Seems like justughs point will still hold true. But I am all for getting more cfm out of what I got. Also jrainman I would love to lower volume of fan and air pulling. How well does insulating ducting work. I might just move that fan out of grow room and put above in attic as well.

Justah broke it down pretty well Raymond. Might wanna recheck your duct sizing chart as well.(6"-flex designed output 75cfm) Magnahelic guages are neat toys play with one sometime add a flowhood and its even better. High volume low velocity is way quieter than low/high velocity. Fan in attic,larger duct to hood and prob stay same to filter but length is also a factor you can play with and find the sweet spot. Filter functions primary,lamp/room cools secondary,and quiet is trial and error till perfection. Want to create optimal "stadic" (my t goes there instead of with the wye)build an insulated plenum (box) for fan reduces fan noise while improving efficiency. Alot of noise is not mechanical negative pressures in tent tell me increased size(duct) and length will help noise tremendously. Take time mounting fan to minimalize vibration in attic. Sorry ray spent a lot of time re-engineering service tech education to apply real world solutions. Play with passive intake size also, My passive cooling won't function below 85f with room door open but if closed 75f on a +90f is easy w/o the use of a/c,hillbilly geothermal for pennies.