Multiple tents on one fan

[newbee1234]

good evening peeps,

quick question for yous regarding exhaust fans. im planning a set up of 3 1.2x2.4x2 tents and am planning the exhaust layout my question is this.

by my calculations i need to move 172.8 m3/hr of air per tent and i have a Gekko 250mm 2500m3/hr acoustic box fan now i know that adding carbon filters reduces the flow rate (by around 25% ive been told) but can i use this fan and put a 125mm carbon filter in each tent and link them up using reducers to one 250mm feed to the fan or would this put the fan under too much strain?

i need this size tent to maximize space and help control smells and heat. this will be my second grow im currently doing my first and using it as a learning curve for my large set up, im planning on using Wilma type set ups in each tent as i really fancy a bash at hydroponics so any help or tips with home built Wilma systems would be most useful

cheers guys and girls

 

[OlderGrower]

I am no expert in air movement by any stretch of the imagination, it would be best if an HVAC guy was able to post his thoughts to get a better answer to your question, but until one shows up I will tell you what I know. If your number of bends in both tents from the filters to the fan were the same at approx. the same length, it should work so long as your fan has the ability to pull that much air. Air flow is reduced with every bend in the ducting and like water, air takes the path of least resistance. so if one tent has a straight shot to the fan and the other tent has multiple bends to get to the fan, the majority of air pulled out by the fan will be through the tent with the straight shot.
Hope this helps, as to how much reduction per bend, I am not sure as to the percentage but I do recall each bend reduces efficiency pretty dramatically.

 

[newbee1234]

sorry for the mess of the drawing but this is what i mean. each tents filter will be 100% straight where all 3 meet at a box with 125mm ducting collars and 1 250 mm collar going to the box fan where it vents out again 100% straight

 

[JuanCarlos]

If you are doing it collector style anyway before the fan why not just use one large carbon filter in a sealed box with inputs from the three tents?

 

[Atulip]

After a little conversion, it appears your fan would be perfect for those 3 tents. Fully circulating air just under 3x a minute.

For your filters, you need to go by the CFM. You want a higher cfm filter than the fan, otherwise smell will leak. Your fab will pull just under 1500cfm, or 500cfm per tent(in a perfect world). With that said you want a cfm rating of 500 or higher for your filters.

For duct reducers, they will restrict airflow some, but it shouldn't be an issue. I would go with oversized filters though. I run an 8" 550cfm filter for my 6" 400cfm fan.

Hope this helps.

 

[MRXC]

That will work 4 sure

 

[newbee1234]

If you are doing it collector style anyway before the fan why not just use one large carbon filter in a sealed box with inputs from the three tents?

i didnt think of that. that would cost far less and be simpler to do wouldn't it? also wouldnt that reduce the airflow less as it has to travel through less carbon filters? has anyone else tried this way before or have any other suggestions?

would anyone know how much the airflow would be reduced with bends in the ducting or have a simple way to work this out i seem to be getting different figures from different places and its very confusing just i like to know exactly what im dealing with in the numbers terms (damn this OCD lol) so any help is greatly appreciated dudes and dudettes

peace out and love they neighbor (snide little bastards could be undercover)

 

[JuanCarlos]

I don't think you have to get that crazy with the measurements. Based on your tent sizes you need to exchange about 1,100 m3/h of air without factoring in loss due to bend, filters, etc. So as far as the bends go I wouldn't waste time calculating out the specifics, your fan can more than double the recommended airflow. With the ducting what I would focus on is all tents having similar length and bends in the ducting. Then get a carbon filter that can match the fan's max output and you are up and running. Take a toke and knock that OCD back.

 

[newbee1234]

I don't think you have to get that crazy with the measurements. Based on your tent sizes you need to exchange about 1,100 m3/h of air without factoring in loss due to bend, filters, etc. So as far as the bends go I wouldn't waste time calculating out the specifics, your fan can more than double the recommended airflow. With the ducting what I would focus on is all tents having similar length and bends in the ducting. Then get a carbon filter that can match the fan's max output and you are up and running. Take a toke and knock that OCD back.

I hear what your saying bud i think its just me lol im just worrying as this is gonna more than double my current grow area and its has to be ultimate stealth mode. and you know how it is when you start over thinking things while im on my pal is doing a 2x2x2 grow and was wondering if 2x600w HIDs would be ok of should he put more in?

 

[JuanCarlos]

Yes, I would toss another 2x600 watt fixtures in your buddies area.

I understand your worries man and it's always good to ask and do your research, but I don't think it's a good idea to involve physics and flow dynamics when planning a grow. That's just way too involved. I am tell you the 2500m3/h fan will be plenty for what you are doing. Get a carbon filter that can support the fan, spend some time making the ducting (as) equal (as possible) and you will be good.