Possible to use 1 460 CFM fan as 1 exhaust & multiple intakes for 4x4x7 tent?

T

Tender Bias

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I am in Canada. I am trying to keep temps low in the tent (29C/89F). Unfortunately I have to keep the tent door open when the lights are on, which means I am wasting precious lumens. Worst comes to worst, I'll get an intake fan as well. It should be interesting to see If I can simply use 1 high static pressure 460 CFM fan.

I am very interested in buying the IObionics 6 in 460 CFM inline DC motor fan with variable speed controller on amazon canada.

I will install this fan in a 4x4x7 tent as an exhaust with a 6 in carbon filter & I will also route 2-3 8 ft 4 in ducts on both sides of the tent (bottom and top) that pulls outside air from a nearby window without any intake fans. I want the fan to exhaust heat and pull in fresh air without any intake fans. Will it satisfy that requirement without any issues? Or is this a pipe dream?

Does anyone have any experience with this fan?
 
Richard Drysift

Richard Drysift

Well-Known Member
You should be able to get away with just this fan and no intake fans at all in a 4x4x7 tent; especially if it is connected to your light hood. So if your tent is 112 sq ft all of the air will be exchanged every .24 mins or let's say slightly more than every 20 secs at full power. I use a similar 350 cfm terrabloom exhaust fan w/controller in my bloom room which is super quiet. My room is also a bit larger than your tent. Set the speed so the walls are almost sucking in and that should pull off most of the heat.
 
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T

Tender Bias

Member
are you sucking heat from the light hood or are you blowing air to the light hood? What kind of controller is included with your 350 CFM terrabloom exhaust fan? Is it a variable speed controller or is it automated (changes airflow depending on temperature and humidity)
 
Renfro

Renfro

Well-Known Member
That type of fan (axial mixed flow) isn't going to handle static pressure loss well so if you have a carbon filter, ducting with bends, the CFM will be drastically reduced. Take that into account when figuring out your ventilation. A centrifugal blower is going to handle the static pressure loss much better and a variac speed control will allow you to slow it down quietly. The downside to the centrifugal blowers is that they are loud. Over sizing the blower and running it at a reduced speed will give the CFM without the noise.
 
T

Tender Bias

Member
Renfro said:
That type of fan (axial mixed flow) isn't going to handle static pressure loss well so if you have a carbon filter, ducting with bends, the CFM will be drastically reduced. Take that into account when figuring out your ventilation. A centrifugal blower is going to handle the static pressure loss much better and a variac speed control will allow you to slow it down quietly. The downside to the centrifugal blowers is that they are loud. Over sizing the blower and running it at a reduced speed will give the CFM without the noise.
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Unfortunately I am too new to this forum to post a link to the fan on amazon canada, but if you google

[2019 Updated] IOBIONICS 6 inch inline Fan with Variable Speed Controller, EC Motor, 460 MAX CFM, Energy Efficient, ETL Listed

It will be the first link.

Customer Service told me that this fan is a high static pressure fan and that it woudl handle high static pressure situtations but I'll read more on the differences between axial mixed flow and centrifugal blowers. Thanks.
 
xtsho

xtsho

Well-Known Member
I have the same size tent and use a 6" 400 cfm fan with controller to exhaust and have three 4" bottom vents open and filtered for passive intake. I can keep the inside of the tent within a few degrees of the outside temp. My tent is in an uninsulated garage so if it's 90 degrees outside it's going to be too hot. I was using a portable air conditioner inside the tent but that became a hassle so I just shut down for a couple months during the hottest part of the summer.

The 460 cfm fan is plenty but you also have to take into account the temperature of the air you're pulling in. If it's 90 degrees outside you're going to be pulling that inside the tent. If you're using a sealed hood that fan will be plenty to exhaust the heat but it won't cool anything down.
 
T

Tender Bias

Member
xtsho said:
I have the same size tent and use a 6" 400 cfm fan with controller to exhaust and have three 4" bottom vents open and filtered for passive intake. I can keep the inside of the tent within a few degrees of the outside temp. My tent is in an uninsulated garage so if it's 90 degrees outside it's going to be too hot. I was using a portable air conditioner inside the tent but that became a hassle so I just shut down for a couple months during the hottest part of the summer.

The 460 cfm fan is plenty but you also have to take into account the temperature of the air you're pulling in. If it's 90 degrees outside you're going to be pulling that inside the tent. If you're using a sealed hood that fan will be plenty to exhaust the heat but it won't cool anything down.
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Temperature outside is cooler like 25 C~77 and it will drop to much cooler as we get closer to winter. It may not become an issue after September but I will still need an exhaust fan so I may as well buy 1 quality exhaust fan that also pulls fresh cool air from my window. I have an open hood running a 400 W metal halide bulb.
 
hotrodharley

hotrodharley

Well-Known Member
Tender Bias said:
Temperature outside is cooler like 25 C~77 and it will drop to much cooler as we get closer to winter. It may not become an issue after September but I will still need an exhaust fan so I may as well buy 1 quality exhaust fan that also pulls fresh cool air from my window. I have an open hood running a 400 W metal halide bulb.
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Your proposed multiple ducts will have to be the exact same length and, as much as possible, be shaped similarly. Otherwise the majority of the air will be pulled through the shortest and straighest duct with little pulled through the longest.
 
T

Tender Bias

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hotrodharley said:
Your proposed multiple ducts will have to be the exact same length and, as much as possible, be shaped similarly. Otherwise the majority of the air will be pulled through the shortest and straighest duct with little pulled through the longest.
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thank you for that tip, i had not considered it. What are your thoughts on this fan and whether it fits these requirements for my 4x4x7 tent?
 
hotrodharley

hotrodharley

Well-Known Member
Tender Bias said:
thank you for that tip, i had not considered it. What are your thoughts on this fan and whether it fits these requirements for my 4x4x7 tent?
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The length of the runs are longer combined than a single fan is rated for using information for dryer booster fans. Max length with a couple of bends is 10’ for a single duct. You’re talking 16’ with 2. Probably underpowered for your design.
 
T

Tender Bias

Member
Exhaust: 7 ft 6 in duct to outside, 4 bends
Intake 1 : 5 ft 5in duct to outside, 3 bends
(maybe) intake 2: 13 ft or 157 in duct outside, 5 bends

intake 2 is a strong maybe because I might not need it and because the length will be significantly different, I may just forgo it. Honestly, considering all the research I have done on fans, I might just buy another 4 in 190 CFM inline axial mixed flow fan (IObionics 4 in fan) for intake 1 and call it a day.
 
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T

Tender Bias

Member
Renfro said:
That type of fan (axial mixed flow) isn't going to handle static pressure loss well so if you have a carbon filter, ducting with bends, the CFM will be drastically reduced. Take that into account when figuring out your ventilation. A centrifugal blower is going to handle the static pressure loss much better and a variac speed control will allow you to slow it down quietly. The downside to the centrifugal blowers is that they are loud. Over sizing the blower and running it at a reduced speed will give the CFM without the noise.
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@Renfro, are there any centrifugal blower fans that you would recommend for a 4x4x7 tent?
 
Renfro

Renfro

Well-Known Member
What type of lighting are you running? I ask because how much heat we have to deal with is key. Also how long are your duct runs? Air cooled reflector? Carbon filter? Will you be using flex duct or the snap seam galvanized for long runs? Do you care about noise? What temperature is the air that will be cooling the tent?

I love the Vortex brand. If noise is an issue, you can oversize the blower and run it on a variac to slow it down so it moves the right amount of air without any noise. Their VTX series is what you want. Their 6 incher is 497 CFM.

https://heavygardens.com/vortex-6-powerfan-497-cfm.html?fee=15&fep=13271&utm_source=google-feed&utm_medium=shopping feed&utm_campaign=SCFeed&utm_source=google&utm_medium=cpc&adpos=1o2&scid=scplpVTX600&sc_intid=VTX600&gclid=EAIaIQobChMIgL-R8J6L5AIVAr3sCh381w7EEAQYAiABEgJlGPD_BwE

If you are venting for heat from a HID light the general rule is tent volume in cubic feet times 2 or 2.5 to get the CFM required. Thats a really general rule. If the air you are using to cool is cold you won't need as much. If you have a lot of ducting and bends and other restrictions like a carbon filter and such then you need to add some CFM to account for the static pressure loss.

If you are running a LED light that doesn't put out much heat then you only need to vent for humidity and CO2, in that case a smaller blower would suffice.

A speed control is handy, some cheap ones make the motor groan because it chops up the wave form and it's no longer a sine wave. I am running a 10 inch vortex on a 2x4 tent with a variac set to 35 volts, trys to suck the tent inside out so I put two high cfm kits on the tent. You can't hear the blower though lol. High CFM kits, those are handy.

I hope all that info helps in your decision making.
 
T

Tender Bias

Member
Renfro said:
Answers in red below

What type of lighting are you running? 400 watt Metal Halide non air cooled open reflector I ask because how much heat we have to deal with is key. Also how long are your duct runs?
Exhaust: 7 ft 6 in duct to outside, 4 bends
Intake 1 : 5 ft 5in duct to outside, 3 bends
(maybe, but most probably not) intake 2: 13 ft or 157 in duct outside, 5 bends
Air cooled reflector? No
Carbon filter? Yes
Will you be using flex duct or the snap seam galvanized for long runs? Flex ducting, as the runs are small and i want the flexibility.
Do you care about noise? Yes, but I am okay with keeping the fan in the tent in the garage. I'd cap the noise at 40 DB. I don't think I will ever run the fan on max though.
What temperature is the air that will be cooling the tent? it will start getting cold now. I am in Vancouver, BC. Day time temps in the tent currently range from 22 C/72 F to 28 C/82.4 on the plant canopy are already. It is starting to get colder now. I am guessing I will probably need a heater in the winter.

I love the Vortex brand. If noise is an issue, you can oversize the blower and run it on a variac to slow it down so it moves the right amount of air without any noise. Their VTX series is what you want. Their 6 incher is 497 CFM. cool, i looked into it, but these are expensive on amazon canada. How do you feel about the Tjernlund M-6 Inline Duct Booster Fan? Would it satisfy my needs? It is selling for 128 CAD without the variable speed controller. What controller would you recommend to go with this fan?


If you are venting for heat from a HID light the general rule is tent volume in cubic feet times 2 or 2.5 to get the CFM required. Thats a really general rule. If the air you are using to cool is cold you won't need as much. If you have a lot of ducting and bends and other restrictions like a carbon filter and such then you need to add some CFM to account for the static pressure loss. Understood, I don't know how my current duct configuration compares but please take a look above and let me know for the Tjernlund M-6 fan.

If you are running a LED light that doesn't put out much heat then you only need to vent for humidity and CO2, in that case a smaller blower would suffice. Not running an LED but I will most probably upgrade to an LED to maximize a 4x4x7 tent

A speed control is handy, some cheap ones make the motor groan because it chops up the wave form and it's no longer a sine wave. I am running a 10 inch vortex on a 2x4 tent with a variac set to 35 volts, trys to suck the tent inside out so I put two high cfm kits on the tent. You can't hear the blower though lol. High CFM kits, those are handy. When you say HIGH CFM kit, do you just mean a high CFM fan?

I hope all that info helps in your decision making.
at the end of the day, I can add another 190 CFM 4 in inline mixed axial fan for intake 1 in case my plan to use 1 460 CFM fan doesn't work, but if ot works, than I can just use that money towards something else

Thank you for your responses. Centrifugal blowers were not on my radar. A lot of youtube videos and posts on the microgrowery reddit do not emphasize blower fans. They highly tout the mixed axial fans like the AC infinity cloudline T6.
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Renfro

Renfro

Well-Known Member
With those lengths of slinky duct and all those bends you will need to oversize the fan for sure, lots of CFM will be lost.

The duct booster fans are garbage, more of a duct restricter, it won't even come close to doing the job. Also those are like 20 bucks at home depot. They are garbage tho.

High CFM kit is extra poles that brace the tent to prevent it from imploding inwards on your plants.

Since you aren't using a cool light source you are gonna need some serious CFM, and remember you can't cool a tent with warm air...

Do the math I told you and add 50 - 60% IMO for all the static pressure loss and get a centrifugal blower as it's the only style that can cope with static pressure loss well. The other styles will fail miserably and you will be buying another fan while your crop fries.
 
T

Tender Bias

Member
Renfro said:
With those lengths of slinky duct and all those bends you will need to oversize the fan for sure, lots of CFM will be lost.

The duct booster fans are garbage, more of a duct restricter, it won't even come close to doing the job. Also those are like 20 bucks at home depot. They are garbage tho.

High CFM kit is extra poles that brace the tent to prevent it from imploding inwards on your plants.

Since you aren't using a cool light source you are gonna need some serious CFM, and remember you can't cool a tent with warm air...

Do the math I told you and add 50 - 60% IMO for all the static pressure loss and get a centrifugal blower as it's the only style that can cope with static pressure loss well. The other styles will fail miserably and you will be buying another fan while your crop fries.
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It's so annoying that I can't paste a link to the fan but i am sure the Tjernlund M-6 Inline fan is a centrifugal blower fan. Other people who have reviewed it ,called it a centrifugal blower fan and it looks like one too. I know what you mean by the cheap booster duct fans at home depot. are you certain the tjernlund m-6 inline fan is not a centrifugal blower fan ?
 
T

Tender Bias

Member
Renfro said:
I searched and came up with a booster like this

View attachment 4381079
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No it's not that one. It's this one.
DCcan said:
Tjernlund M-6 Centrifugal blower, Im looking at the 8" for a 4x4. Just got the variacs. They are awesome
Same fan listed for $20 less under AmeriFan name, same mfgr:
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Thank you so much for mentioning this,posting a picture and a link. I'd really appreciate some likes to my posts so I could get link posting power to help explain my posts.
 
T

Tender Bias

Member
DCcan said:
Tjernlund M-6 Centrifugal blower, Im looking at the 8" for a 4x4. Just got the variacs. They are awesome

Same fan listed for $20 less under AmeriFan name, same mfgr:

What variable speed do you use in conjunction with this fan?
Tender Bias said:
No it's not that one. It's this one.


Thank you so much for mentioning this,posting a picture and a link. I'd really appreciate some likes to my posts so I could get link posting power to help explain my posts.
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DCcan said:
Tjernlund M-6 Centrifugal blower, Im looking at the 8" for a 4x4.
Just got the variacs for an upgrade. They are awesome

Same fan listed for $20 less under AmeriFan name, same mfgr:


I am looking at the 6 in version. Do you know of a cheap reliable controller that I can use with this fan? I'd appreciate some recommendations. Is there a cheaper good daytime/nightime variable speed controller?
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