1 fan with 3 filters vs 3 fans + 3 filters for three tents?

Anyone have any experience using one fan for multiple tents/rooms? To me it seems much more efficient to have one very powerful fan instead of three smaller ones. Each tent would have its own carbon filter inside the tent all being sucked by the one powerful fan.

I plan on having one large flower room, a smaller mother room and then another flower room smaller than the mother room. I'd split the fan with a Y connector, one end going straight into the large flower room and the other end being split again with a Y connector going to the two smaller rooms with appropriate downsizing connectors.

Is this a good way of doing it or would seperate fans be better? The large flower room is going to have 4x 600w HPS, the mother room a 600w MH, the smaller flower room a 400w HPS. No aircooled hoods so its going to be a very powerful fan.

no cool tubes.........................no your system will fail and cook the plants

the tents /rooms would have to be completely sealed and the amount of air u would need at the start would rip the plants up ......sommething like that u need 10 to 20 miles a hour solid cool wind

your best bet is going to be using s passive intake system with a strong exhust ..............each tent own fan and carbon scrubber sucking out ....the tents lower flap open to allow passive air and then use a ac in that main room the tents are in a strong one to keep the intake temps cool .....u are going to want the fans to vent that room atleast 1 once every 30 secs so the air temp in there staies cool ...........the plants are going to heat up alot from the amount of lightand engery but the air will too

a 4x4x6 is 108 cfm i am running a 600watt cool tube the math comes out i need to have atleast 280 cfm to keep it cool for the plants at a intake high temp of 78 (outside air at 7

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[FONT=Verdana,Arial,Helvetica] [FONT=Verdana,Arial,Helvetica] Dan's Method Calculating By Room Volume You will find many calculations on the web for sizing a fan for ventilating indoor gardens; however, what many of these calculations fail to take into consideration is the friction loss on carbon filters and increased temperatures from HID lights. So here's my calculation method which you can use as a guide for sizing an exhaust fan for a growing area (keep in mind that this calculation will give you the lowest required CFM (Cubic feet of air per minute) required to ventilate the indoor garden.) Step 1: Room Volume First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet. Step 2: CFM Required Your extraction fan should be able to adequately exchange the air in an indoor garden once every three minutes. Therefore, 512 cubic feet / 3 minutes = 171 CFM. This will be the absolute minimum CFM for exchanging the air in an indoor garden. Step 3: Additional factors Unfortunately, the minimum CFM needed to ventilate a indoor garden is never quite that simple. Once the grower has calculated the minimum CFM required for their indoor garden the following additional factors need to be considered: Number of HID lights — add 5% per air cooled light or 10-15% per non-air cooled light. CO2: add 5% for rooms with CO2 enrichment Filters: if a carbon filter is to be used with the exhaust system then add 20% Ambient temperature: for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%. An Example In our 8' x 8' room we have 2 x 1000w air cooled lights, and we plan to use a carbon filter. We also plan to use CO2 in this room. The ambient temperature is 90 °F (32°C), however, we will be using air from another room that is air-conditioned. Here's the minimum required CFM to ventilate room: 1) Calculate the CFM required for room (see above.) 2) Add 10% (for 2 air cooled lights.) 3) Add 5% of original CFM calculation (For CO2.) 4) Add 20% of original CFM calculation for Carbon Filter. 5) Air is coming from air-conditioned room so no need to add any other percentages. 6) CFM = (171 CFM) + (171CFM x 10%) + (171 CFM x 5%) + (171CFM x 20%) + ( 0 )= 231 CFM. This is the absolute minimum CFM required to ventilate your room. The next step might seem to match the closest fan to this CFM. However, for this example I'd choose a six inch fan with a CFM of around 400 or more, and a 6 inch carbon filter to match. The extra CFMs may seem a bit excessive (calculations on most indoor gardening websites would recommend a 4" fan and a 4" carbon filter) but it's always better to over-spec since we need to compensate for air resistance in ducting too. Also, as we are using a carbon filter we will need to match the fan with the filter so that the fan that will neatly fit onto the filter. If all the variables are kept the same and we changed the room size from 8' x 8' to a 12' x 12' then the minimum required CFM would be 519 CFM. The All-Important Inflow! An intake port can be anything from a gap under the door to an open window - even a hole in the wall. The best place for an intake port is diagonally opposite from your exhaust fan; that way, air has to pass across the entire room - very efficient. You can put a piece of screen over the opening to keep insects and animals out, a piece of A/C filter to keep dust out, or a louvered shutter or backdraft damper that opens when the fan turns on and closes when it turns off. You can also use a motorized damper. This gets installed in-line with your ducting and is plugged into whatever device controls your exhaust fan. When your fan turns on, it allows air to pass. When your fan shuts off, it seals completely, preventing CO2, air, etc. from passing. You can get creative with these devices and use one fan to control two rooms, etc. One additional note about intake ports - you will see much better results from your exhaust system if you install a second fan to create an active (as opposed to passive) intake system. Normally, when your exhaust fan sucks air out of your room, air is passively going to get sucked back into the room. By installing a second fan on the intake side, you will reduce the amount of negative pressure created in the indoor garden, thereby cutting down greatly on the amount of work the exhaust fan has to do and allowing much more air to pass through. If you're not sure or you don't want to spend the money, start out with just an exhaust fan. If it's not performing as well as you thought it would, try adding an intake fan - you'll smile when you see the difference! [/FONT][/FONT]

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[FONT=Verdana,Arial,Helvetica] [FONT=Verdana,Arial,Helvetica] Fred's Method Calculating By Wattage Hello there. First off, I'm used to working with Celsius, not Fahrenheit, but I've done my best to provide formulas for both. My method for calculating fan requirements does not cover active cooling with air conditioning systems or cool-tube designs. We're talking about everyday grow chambers here, totally enclosed for airflow control, with no large amounts of radiant heat into or out of the box. Your mileage may vary some for these reasons. RIGHT THEN, LET'S GET STARTED: 1) Start at the beginning and design this right! Before you even buy or cut anything for your new project, determine the highest temperature that your intake air will ever be when lights run. Call this T (inlet). 2) Use these formulas to determine difference in temperature you can tolerate. 80°F (27°C) is just about the optimal for growing most plants. You can go up to 76°F (30°C) if you have to, but aim for 80°F (27°C). Tdiff = 27 °C – T (temperature of inlet air) 3) Add up wattage for all power sources in your indoor garden. Lights, pumps, heaters, humidifier, radio, coffee maker, whatever! Add it ALL up and call it Watts. If it is on for more than three minutes and uses more than a watt, add it up. This will make your number worst-case and therefore a conservative value. 4) Compute the absolute minimum fan power you will need using the following formulas. Fan power is measured in the amount of air (cubic feet) shifted per minute. The formula below is the minimum fan rating you must have to achieve your temperature goals. You will have to increase fan power to compensate for duct constriction, small inlets, carbon scrubbers, screens, or other items that block airflow. CFM = 1.75 x Watts /Tdiff (in Celsius) If you prefer to work in Fahrenheit, try this formula: CFM = 3 x Watts / Tdiff (in Fahrenheit) 5) Get at least this fan power or don't come and ask questions! If you are going to have more than one fan, they should be mounted side-by-side rather than inline if you want to add their different CFM ratings. For inline fans, use the lowest airflow rating of all fans in the path. A fan on the inlet and a fan on the exhaust of the box are considered inline fans. Fans just circulating air inside the indoor garden should not be counted for airflow but must be included in your initial wattage calculations. OK, TO SEE THESE FORMULAS IN ACTION WE'RE GOING TO HAVE TO DO A LITTLE NUMBER CRUNCHING: An Example Ok, let's say you have 2000 watts in a 8 foot by 8 foot room with an 8 foot ceiling height. So what amount of air do I need to move to keep the room at 82°F (28°C)? My incoming air temperatures are 68°F (20°C) during the lights on period. Tdiff = 28 – 20 = 8°C For Celsius the formula comes out at: CFM = 1.75 x 2000 / 8 = 438 CFM For Fahrenheit we get the following: Tdiff = 82 – 68 = 14°F CFM=3x2000/14=429 CFM Remember, Tdiff shows how much your temperatures will rise above your inflow air temperature for a given wattage and air movement. If you are adding any carbon scrubbers or extensive ductwork, this is where you add to the fan size to account for air pressure losses. You have to move this many CFM, or the numbers don't come out right. Exactly how much these items diminish your airflow depends on your exact configuration and is beyond the scope of this introductory article! What to do when your outside temperatures are higher than your maximum allowed indoor garden temperatures! YOU HAVE A FEW CHOICES: 1) Stop growing for a while till things cool off or try running your grow lamps at night when inlet air will be cooler. 2) Reduce your lighting to drop the heat load. Not good if the incoming air is already over critical when it arrives in the box. Might be possible if the inlet air temperature is lower but you are running too many lights to keep up with the cooling. 3) Use active air conditioning. [/FONT][/FONT]

[FONT=Verdana,Arial,Helvetica] [/FONT][FONT=Verdana,Arial,Helvetica]Okay, there you have it – two very different approaches to calculating your extraction requirements. What do you think? Do you prefer either or neither of these approaches? Or perhaps a combination of the two? [/FONT]
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[FONT=Verdana,Arial,Helvetica] [FONT=Verdana,Arial,Helvetica] My Simple Rule of Thumb IF YOU WANT TO KEEP THINGS REALLY SIMPLE, JUST REMEMBER THAT YOU WANT TO REPLACE THE AIR IN YOUR INDOOR GARDEN EVERY ONE TO THREE MINUTES. IF YOU'RE IN A HOT AREA, EXCHANGE IT EVERY MINUTE; IF YOU'RE IN A COOLER AREA, YOU CAN TAKE UP TO THREE MINUTES. [/FONT][/FONT]

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Good reply, thanks. Although let me go into a bit more detail. First of all I work in metric so bear with me.

I am currently running a 600w HPS in a 120x120x200cm (2.88m3) tent. I am running a 280m3/h fan through a carbon filter. That means I am venting the volume of the grow room 1.6 times every minute (Yes I know I am venting less because carbon filter reduces intake but for simplicity let's ignore the carbon filter because I am only comparing my current grow to my future grow that's going to have a carbon filter as well so it balances out) Temps stay pretty stable at around 26-27c.

The large flower room would be 240x240x200 (11.52m3) the fan I plan on running sucks 2300m3/h which will be split in half so 1150m3/h. That means I would be venting the volume of the grow room 1.6 times every minute. The carbon filter would be placed strategically right above the lamps in the middle, so in theory a lot of the heat that the lamps produce would be sucked out relatively quickly, not as quickly as cooltube/aircooled hoods but still pretty quick. I would have lots of passive intake sucking from a cool part of the house. The hot air would be exhausted into another room or straight outside.

Are you telling me it wouldn't work? I've done the math and it works out, I would be venting about the same amount of air relative to space and amount of lights but perhaps its not as simple as that? I'd also like to add I live in a mild climate, the heat from the lamps would be heating my house in the winter, summers can get hot but not that hot, we're still talking very mild summer, nothing compared to say California. It never really exceeds 25c outside in the summer.

I know cooltubes/hoods would be simpler and I've definitely looked into those options but I love my adjust a wing way too much, I'm afraid cooltubes/hoods won't reflect the light as good and reduce light intensity due to the glass.

It is doable from a air scrubbing perspective but not sure how it will fair for cooling.

Connect you fan directly to your filter and put it in you big tent high up.
You then need to connect each of you tents together with ducting. So connect big flower tent to small flower tent then connect small flower tent to veg tent. this will create a passive effect across all 3 tents.

Big tent will pull air from 2nd flower tent, this in turn will pull air from veg tent. you will have to seal all other vents in all tents to keep them as air tight as possible. You may be able to leave your veg tent out of the loop, minimal smell in veg so not really a need to scrub the air. Like I said earlier, this will creat negative pressure and scrub your smells but will not be very efficient for cooling needs.

MrMeanGreen said:

It is doable from a air scrubbing perspective but not sure how it will fair for cooling.

Connect you fan directly to your filter and put it in you big tent high up.
You then need to connect each of you tents together with ducting. So connect big flower tent to small flower tent then connect small flower tent to veg tent. this will create a passive effect across all 3 tents.

Big tent will pull air from 2nd flower tent, this in turn will pull air from veg tent. you will have to seal all other vents in all tents to keep them as air tight as possible. You may be able to leave your veg tent out of the loop, minimal smell in veg so not really a need to scrub the air. Like I said earlier, this will creat negative pressure and scrub your smells but will not be very efficient for cooling needs.

Click to expand...

Why would I have a setup like that? That is going to suck the heat from the smaller tents into the larger tents which is going to increase the chances of heat issues, I think you misunderstand my idea, here's a pic:

The fan will probably mounted in another room with insulated ducting going to each tent, the carbon filters will be placed high up in each tent. The fan will exhaust into another room or straight outside. Each tent will have at least one passive intake being sucked from another room.

So each room has its own filter, the only difference is that there is one powerful fan exhausting them all instead of one separate fan for each one. The biggest issure I'm worried about is that it might not suck the right amount from each one but if I downsize each vent appropriately it should sorta just balance out, I'm hoping.

I'm a bit confused.

Why ask for advice from knowledgable folk and then try to disregard it because you hope it will work.


If this were me setting up this grow I would opt for a single fan and filter per tent.


What if your large fan fucks up?

All tents are without a fan.

Then there is the hoping you get the balance of downsizing and duct runs exactly right to draw equally from each tent.

The wisest choice is the one everyone is recommending.

Single fan per tent.


J

i'm here to argue with jon again lol.

i think if you run the flower tents at night and you could get away with it. i do something similar with an 8" tornado fan but not in a separate room and it's 2 pairs of 600 cooltubes.

but again back to square one why wouldn't you run the three fans? how big is the fan you are looking at? and can you stand the sound of a hurricane in the house or can the neighbours next door? my little 8" fan makes a bit of a racket even with silencer fitted.

ghb said:

i'm here to argue with jon again lol.

i think if you run the flower tents at night and you could get away with it. i do something similar with an 8" tornado fan but not in a separate room and it's 2 pairs of 600 cooltubes.

but again back to square one why wouldn't you run the three fans? how big is the fan you are looking at? and can you stand the sound of a hurricane in the house or can the neighbours next door? my little 8" fan makes a bit of a racket even with silencer fitted.

Click to expand...

I'm getting quite accustomed to it GHB. Lol.


I'm not saying it wouldn't work especially running night times.


My issue would be fail safe of the fan.



J

no it not going to work

there is alot more to it ..............first breaking the air stream up ..........it is always going to go the path of least effort so u are going to need a damping system on the tubes so u can get the same speed from all of them ............then u have to dail it in

u have 2 juctions in there the air is going to want to go down the first one more then the second one becuase of the extra split ..............when working with air i look at like water to make it easier to understand

the honest truth is this method is more effort and tweaking then it is worth ..........then once u have it to the tent if the pressure coming out is to high u rip leaves off the branches so u need a defuser and that will reduce the speed

if u are commited to this ...........it might work if u connect all 3 at the top and in from there use a y juctions inside the tent and on the y part put a damper on it so the air is sucking out u could controll the force alot easier then feeding it in .......use the fan to vent it out instead of feeding it in ........then u have the choice of adding the scubbers back in if u need too and open the dampers little more

if u use a a 6 inch ducting u can get a 240 cfm booster fan and place those between the tent to gain abck what u lost on sucking from the first time

then u just need to turn on the lights and adjust the damper for the heat lower heat open wider higher heat close them some ...................but the boosters will be needed the one on the end will have the least vaccum on it so i make it the smallest one then medium them large with the fan next to the largest first

or even think about using 4 inch ducting on the last tent so the smaller size increases the speed

@jon, I've been planning this for a while and have thought it through carefully, I think it will work, actually I'm quite sure it will work but I'm not completely sure. I'm not disregarding any advice I just want a proper explanation as to why it wouldn't work. I only came here to verify that it will work before I spend 2000+ USD on equipment but I am happy to be proven wrong, so far I haven't been.

I don't want air cooled hoods unless I absolutely have to, I think if someone lives in a warm climate (as some of you may do) they might look at my "vent plan" and think its impossible because they're imagining it in their climate. I've seen "experienced folk" telling people they can't run a certain fan with a certain size tent with a certain light and it's what I've been running all summer without any problems whatsoever. Remember, I don't live in a warm climate. There's going to be a constant stream of cool air coming from the lower passive intake being sucked upwards into the carbon filters.

This is the exact fan I planned on getting: http://www.canfan.nl/im2502310.html Here are some figures (I'll even add the imperial measurements for those of you living in stone age countries )

The fan is 250mm (10 inches) 2310m3/h (1360cfm)

The first Y Split going into large flower room would be downsized to 200mm (8 inches) connected to a carbon filter rated at 1500m3/h (882cfm)

The second split will be split again, first one going to mother room being downsized to 160mm (6.4 inches) connected to a carbon filter rated at 500m3/h (294cfm)

The final split will be going to the small flower room being downsized to 100mm (4 inches) connected to a carbon filter rated at 300m3/h (176cfm)

Now, I am aware that its not going to be balanced perfectly and that the carbon filter ratings only just match the full capacity of the fan, the fan would not be run on full capacity, I would have one of those switches where you reduce it.

The reason I don't want to have several fans is simply because it seems inefficient, I would anyway need a large fan for the large flower room, so I figured why not get a slightly more powerful fan and have it suck them all, then place it in a separate room in the middle of the house with insulated ducting to reduce noise. Yes it might be harder to setup than separate fans, but once its all setup it should be more efficient (I'd like to add electricity is a big factor for me, any extra watts I can save is a big bonus).

I understand the concept of balancing ventilation, I even contemplated getting one of those things you place in the opening to measure the exact air draw through each vent then downsizing them appropriately. But I think the way I have it planned now should be close enough. It doesn't have to be that precise, there should be margins in my calculations so even if one draws less than I thought it should still be enough.

Regarding the fan breaking, I am aware that's a problem, I could easily install something that alerts me if the fan breaks, the fan is only around 600 USD, I might even two fans and just have one lying around as a backup. They seem to be very high quality fans so I don't think it will break. If I have three separate smaller fans there is a bigger risk of one of them breaking.

---

Actually, if I work out the surface area of all three holes wouldn't that give me an exact figure of where the air is going to be drawn? *Put's Maths hat on*

Surface area of each opening
200mm = 314cm2
160mm = 201cm2
100mm = 78cm2

Total = 593cm2

200mm: (314/593)*100 = 53% -- 2310 m3/h * 0.53 = 1224 m3/h
160mm: (201/593)*100 = 34% -- 2310 m3/h * 0.34 = 785 m3/h
100mm: (78/593)*100 = 13% -- 2310 m3/h * 0.13 = 300 m3/h

Is that correct or am I over simplifying things? It seems my guesses at appropriate vent downsizing were pretty accurate with the exception of the mother room, if I downsize the mother room to a 150mm or a 125mm or make the larger mother room into 250mm instead of 200 it should be better. I'm too tired to do the calculations now but could someone confirm that this method works for balancing vents? I honestly don't know, I just used common sense and basic maths

yes u forgot the lights and the intake air and the humity of the area

he is running 4 600watt no cool tubes the 2nd posting if wwe use his math that is 60% more cfm needed to keep the temp right (15% more cfm for each open 600watt)........then add anouther 15% for the 600 mh and add 10% to the 400.......85% more in total need and that is only one factor

apple123123 said:

Is this a good way of doing it or would seperate fans be better? The large flower room is going to have 4x 600w HPS, the mother room a 600w MH, the smaller flower room a 400w HPS. No aircooled hoods so its going to be a very powerful fan.

Click to expand...

justugh said:

Dan's Method Calculating By Room Volume You will find many calculations on the web for sizing a fan for ventilating indoor gardens; however, what many of these calculations fail to take into consideration is the friction loss on carbon filters and increased temperatures from HID lights. So here's my calculation method which you can use as a guide for sizing an exhaust fan for a growing area (keep in mind that this calculation will give you the lowest required CFM (Cubic feet of air per minute) required to ventilate the indoor garden.) Step 1: Room Volume First the volume of the room needs to be calculated. To calculate multiply length x width x height of growing area e.g. A room that is 8' x 8' x 8' will have a volume of 512 cubic feet. Step 2: CFM Required Your extraction fan should be able to adequately exchange the air in an indoor garden once every three minutes. Therefore, 512 cubic feet / 3 minutes = 171 CFM. This will be the absolute minimum CFM for exchanging the air in an indoor garden. Step 3: Additional factors Unfortunately, the minimum CFM needed to ventilate a indoor garden is never quite that simple. Once the grower has calculated the minimum CFM required for their indoor garden the following additional factors need to be considered: Number of HID lights — add 5% per air cooled light or 10-15% per non-air cooled light. CO2: add 5% for rooms with CO2 enrichment Filters: if a carbon filter is to be used with the exhaust system then add 20% Ambient temperature: for hot climates (such as Southern California) add 25%, for hot and humid climates (such as Florida) add up to 40%. An Example In our 8' x 8' room we have 2 x 1000w air cooled lights, and we plan to use a carbon filter. We also plan to use CO2 in this room. The ambient temperature is 90 °F (32°C), however, we will be using air from another room that is air-conditioned. Here's the minimum required CFM to ventilate room: 1) Calculate the CFM required for room (see above.) 2) Add 10% (for 2 air cooled lights.) 3) Add 5% of original CFM calculation (For CO2.) 4) Add 20% of original CFM calculation for Carbon Filter. 5) Air is coming from air-conditioned room so no need to add any other percentages. 6) CFM = (171 CFM) + (171CFM x 10%) + (171 CFM x 5%) + (171CFM x 20%) + ( 0 )= 231 CFM. This is the absolute minimum CFM required to ventilate your room. The next step might seem to match the closest fan to this CFM. However, for this example I'd choose a six inch fan with a CFM of around 400 or more, and a 6 inch carbon filter to match. The extra CFMs may seem a bit excessive (calculations on most indoor gardening websites would recommend a 4" fan and a 4" carbon filter) but it's always better to over-spec since we need to compensate for air resistance in ducting too. Also, as we are using a carbon filter we will need to match the fan with the filter so that the fan that will neatly fit onto the filter. If all the variables are kept the same and we changed the room size from 8' x 8' to a 12' x 12' then the minimum required CFM would be 519 CFM. The All-Important Inflow! An intake port can be anything from a gap under the door to an open window - even a hole in the wall. The best place for an intake port is diagonally opposite from your exhaust fan; that way, air has to pass across the entire room - very efficient. You can put a piece of screen over the opening to keep insects and animals out, a piece of A/C filter to keep dust out, or a louvered shutter or backdraft damper that opens when the fan turns on and closes when it turns off. You can also use a motorized damper. This gets installed in-line with your ducting and is plugged into whatever device controls your exhaust fan. When your fan turns on, it allows air to pass. When your fan shuts off, it seals completely, preventing CO2, air, etc. from passing. You can get creative with these devices and use one fan to control two rooms, etc. One additional note about intake ports - you will see much better results from your exhaust system if you install a second fan to create an active (as opposed to passive) intake system. Normally, when your exhaust fan sucks air out of your room, air is passively going to get sucked back into the room. By installing a second fan on the intake side, you will reduce the amount of negative pressure created in the indoor garden, thereby cutting down greatly on the amount of work the exhaust fan has to do and allowing much more air to pass through. If you're not sure or you don't want to spend the money, start out with just an exhaust fan. If it's not performing as well as you thought it would, try adding an intake fan - you'll smile when you see the difference!

Click to expand...

those are the factors to add into the math.......u have only step one and two u are missing the important 3 ......this is where the control of the evo math comes in

You put your 2 flower room lights on opposite each other and your veg tent, I am assuming will be using CFL's. So no you won't be increasing the heat like you describe, you will be disipating heat around all 3 tents. Also during the winter months you will be heating the other rooms when lights are out.

I didn't misunderstand what you are planning, good luck with the differing ducting lengths and sizes. How do you intend measuring their suction to level them out?

justugh said:

yes u forgot the lights and the intake air and the humity of the area

he is running 4 600watt no cool tubes the 2nd posting if wwe use his math that is 60% more cfm needed to keep the temp right (15% more cfm for each open 600watt)........then add anouther 15% for the 600 mh and add 10% to the 400.......85% more in total need and that is only one factor

Click to expand...

justugh said:

those are the factors to add into the math.......u have only step one and two u are missing the important 3 ......this is where the control of the evo math comes in

Click to expand...

Well I am already running a 120x120x200 with a 600w HPS (without cooltube) using a 280m3/h fan in the same climate, my large flower room will be 4 times as big with 4 lights so 280m3/h x 4 = 1120m3/h as long as I am drawing at least 1120m3/h I should be ok, right? Also, my calculations were only to calculate the amount that each fan would draw, I already know how much I need to draw (based on my current grow, right?) My calculations were to work out how much I need to downsize each vent so that its balanced. Is my way of working out the area of each vent, then making them into a percentage an accurate way to work out how much each vent is going to draw?

MrMeanGreen said:

You put your 2 flower room lights on opposite each other and your veg tent, I am assuming will be using CFL's. So no you won't be increasing the heat like you describe, you will be disipating heat around all 3 tents. Also during the winter months you will be heating the other rooms when lights are out.

I didn't misunderstand what you are planning, good luck with the differing ducting lengths and sizes. How do you intend measuring their suction to level them out?

Click to expand...

Check out my calculations in the previous post, I calculated the surface area of each vent being downsized, turned them into percentages then multiplied the percentages by total fan suction, is that a correct way to balance vents?

apple123123 said:

Well I am already running a 120x120x200 with a 600w HPS (without cooltube) using a 280m3/h fan in the same climate, my large flower room will be 4 times as big with 4 lights so 280m3/h x 4 = 1120m3/h as long as I am drawing at least 1120m3/h I should be ok, right? Also, my calculations were only to calculate the amount that each fan would draw, I already know how much I need to draw (based on my current grow, right?) My calculations were to work out how much I need to downsize each vent so that its balanced. Is my way of working out the area of each vent, then making them into a percentage an accurate way to work out how much each vent is going to draw?



Check out my calculations in the previous post, I calculated the surface area of each vent being downsized, turned them into percentages then multiplied the percentages by total fan suction, is that a correct way to balance vents?

Click to expand...

You cannot apply a formula to the resistance your ducting will create.

apple u will do what u want

we tried to help u save your crops .................please rem when something breaks or u forgot to account for something we did try to help u .............your tring to do it with all numbers and u are not account for the varibles of the area

drawling it all out with only one fan or feeding it in is not wroth the time and trouble other wise u would have seen that grow design more and more

i am sorry your logic is messed up i figured out how to do it correctly but the cost of it is crazy

u need 4 wired wind speed metters 3 electrical controlled damper and a computer program that has not be designed yet ...........meters go in the ducting they tell u what u are getting feeds to the computer the computer uses the dampers to fix the speeds and amount going to where it is needed .............u can not do this is any other way u taken reading at the end of each tube and then hand tuning it would be hours of work and then u would just settle for something close

as the amish fucker from the middle of bum fuck nowhere i vote u go 3 fans venting with a passive system ..........the 3 fans can feed into one exhust out just add back flow dampeners

but this is your shit your place your work do as u see fit sir .......good luck and sorry about the bad luck /u can bitch slap me if it all works out and then i owe u a shot of shine

justugh said:

apple u will do what u want

we tried to help u save your crops .................please rem when something breaks or u forgot to account for something we did try to help u .............your tring to do it with all numbers and u are not account for the varibles of the area

drawling it all out with only one fan or feeding it in is not wroth the time and trouble other wise u would have seen that grow design more and more

i am sorry your logic is messed up i figured out how to do it correctly but the cost of it is crazy

u need 4 wired wind speed metters 3 electrical controlled damper and a computer program that has not be designed yet ...........meters go in the ducting they tell u what u are getting feeds to the computer the computer uses the dampers to fix the speeds and amount going to where it is needed .............u can not do this is any other way u taken reading at the end of each tube and then hand tuning it would be hours of work and then u would just settle for something close

as the amish fucker from the middle of bum fuck nowhere i vote u go 3 fans venting with a passive system ..........the 3 fans can feed into one exhust out just add back flow dampeners

but this is your shit your place your work do as u see fit sir .......good luck and sorry about the bad luck /u can bitch slap me if it all works out and then i owe u a shot of shine

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I'm sorry but are you retarded? I don't mean that in an offensive way but your post makes no sense whatsoever, your 'how to do it correctly' is just plain idiotic and your level of illiteracy for someone who I'm presuming was raised in the US, a country where English is the main language is simply mind blowing. Why can't you use capital letters and punctuation? If you just re-read what you write you should be able to spot the spelling mistakes. If you're dyslectic why not get a spellchecker? It's painful to read your text. It annoys me that you think 3 fans is better than 1, I am after efficiency, one fan will 100% guaranteed be more efficient than running 3 fans. Yes it might be hard and complicated to setup but I don't care about that, once its running it will be better.

MrMeanGreen said:

You cannot apply a formula to the resistance your ducting will create.

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That's not really what I'm after though, what I'm after is: If I connect a 250mm (10 inches) fan and split it into 3 different sized vents, I am 99.5% sure there is a way to mathematically work out how much each will draw, now sure it might not be 100% accurate (due to slight variation in ducting length and so on), but if the vents are similar length then there must be a way to calculate it within say 90-95% accuracy. You can work out virtually anything with maths. There is no way you're telling me that the only way to do this is to connect it all up and individually measure each vent? Maths can solve anything, hopefully someone who has done this before or someone who works setting up ventilation systems can chime in. Who knows, maybe I am wrong.. don't think so though.

lets see what u do................. u are the one that is missing what the rest of us see

prove me wrong i will run up and kiss a state trooper on the lips .................but i am sure i am right so not worried i will have too