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booster fan vs inline exhaust fan

budsofmadison

budsofmadison

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so i got an ac infininity 6 inch booster fan blowing fresh air into my tent
i have a 6 inch spider farmer exhaust fan blowing air out
with both fans at full throttle, the 6 inch booster fan is blowing more air in my 3x3 tent then what the 6 inch spider farmer exhaust can take out does that make sense should the 6 inch exhaust fan be taking out more air then a 6 inch booster fan can blow in
 
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ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
i have my intake fan at the bottom of my tent i figure that gives me airflow down there i also think having the intake fan at the bottom and exhaust at the top means fresh air is being brought up
 
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ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
im far from an expert but to me seems the way u have it as soon as u bring in fresh air the exhaust is pulling it out
 
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ineedmygranny said:
no expert here at all but, are you saying a fan on the intake and no exhaust fan?
i'd think that you would have positive pressure to your room unless you had massive exhaust ports.
Click to expand...
i know your not talking to me but if you leave you vents open in your tent u do not need an intake fan just an exhaust fan
 
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budsofmadison said:
im far from an expert but to me seems the way u have it as soon as u bring in fresh air the exhaust is pulling it out
Click to expand...
could very well be true.
i have 1-4" passive intake , 1-8" passive intake and 1-4" with a fan all at the bottom and of course it exhausts from the top.
also have 2 -12" wall mounted hurricane fans moving shit tons of air and a tower fan on stand by.
i "think" the air gets mixed enough before it exhausts
 
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ineedmygranny said:
could very well be true.
i have 1-4" passive intake , 1-8" passive intake and 1-4" with a fan all at the bottom and of course it exhausts from the top.
also have 2 -12" wall mounted hurricane fans moving shit tons of air and a tower fan on stand by.
i "think" the air gets mixed enough before it exhausts
Click to expand...
im trading my tower fans in for some ac infinity clip on fans lol
 
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ineedmygranny said:
there was a HVAC tech on the other site, did he make it here?
don't remember the name
Click to expand...
Yes he did :D

ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
Yes the less duct you have the more air you will get out of the same blower. Also turns make a difference. So the fan in the back on your picture if you just flip that around and get rid of the u-bend of duct would give you more airflow. A tight radius 90 degree turn adds the equivalent of 5 feet of duct in terms or air resistance. So that u bend is like adding 10 feet to your duct.
 
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Scotty 420 said:
Yes he did :D


Yes the less duct you have the more air you will get out of the same blower. Also turns make a difference. So the fan in the back on your picture if you just flip that around and get rid of the u-bend of duct would give you more airflow. A tight radius 90 degree turn adds the equivalent of 5 feet of duct in terms or air resistance. So that u bend is like adding 10 feet to your duct.
Click to expand...
your awesome bud.
glad you made it here.
if i placed the fan on the hard mounted exhaust and placed the ducts str8 out with a 45 degree bend in opposite directions would that improve airflow?
 
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Aqua Man said:
Fan on the output up top and passive intake from the flaps on the bottom.
Click to expand...
That's how I have mine set up. The fan is outside the tent, on the top. The intake is at the bottom at the opposite side of the tent, so there's a crossflow of air from corner to corner.

I also have a sensor on the output to measure temperature and humidity. I added it out of curiosity. Its readings are usually close to what the sensors inside the tent are reporting.
 
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Rootsruler said:
Why do you need a booster fan? I run the T6 in my 5 x 5 and it exchanges plenty of air.

I have the exhaust fan mounted on the roof of the tent sucking air out while the bottom vents flow air into the tent and up through the canopy.

In case you don't know you want 3 air exchanges a minute minimum in your tent. Mine is a 5' x 5' x 6.5'. That gives me 162.5 cubic feet of space. I have the same ACI T6 you have. It maxes at 402 cfm. 162.5 x 3 = 487.5 cfm. I need a bigger fan. I'm looking at the T8 as a replacement. It puts out 807 cfm.
Click to expand...
I started with just an 6” in-line booster fan in both tent zones. (Zone 2 & 3 share air)

I found humidity and temp changes needed a better balance than just the draw of the top fans.

When I got the T6 with controller it was a game changer but still has humidity vs temp issues. Especially at lights out. Putting the old boosters in the bottom vent holes solved that but manually.

The hole, at 6”, is enough to leave it off some days. Others it’s enough to leave on low. Once in a while, like the crazy hot/cold weeks we just had, I have to turn them way up.

I do this because it saves wear and tear on the main fans and it’s cheaper than buying or running other equipment in the same space.

If I open the basement window with the bottom booster fan on it gets me to 50% RH fast. Without driving the temp down to 18*c. Booster pulls in but main fan is off with just currant pushing through.

Probably doing it all wrong. 🤣
 
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budsofmadison said:
the ac fan is good in my 4x4 so u think a 6 inch exhaust would be too much for a 3 x3
Click to expand...
My T6 is great in a 3x3. Set to never go higher than 6 and step up smoothly rather than full blast.

I’ve had to replace furnace fans for myself and others so usually get bigger so it works less for same results. Like over engineering. You don’t need to run it full if half is good but if you need more you have it. It’s only a few $$ more for the next size so I’m hoping to future proof my purchase.
 
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ineedmygranny said:
not trying to hijack this thread but would fan placement make a difference?
in my case if i mounted the fans direct to the exhaust ports on the wall and ran the ducting from them would airflow increase?
didn't see a need to start a new thread as this might help budsofmadison also
Click to expand...
I put my fan outside to pull air rather than push. Also little less heat inside helps. More room for light to go up too.
 
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Scotty 420 said:
Yes he did :D


Yes the less duct you have the more air you will get out of the same blower. Also turns make a difference. So the fan in the back on your picture if you just flip that around and get rid of the u-bend of duct would give you more airflow. A tight radius 90 degree turn adds the equivalent of 5 feet of duct in terms or air resistance. So that u bend is like adding 10 feet to your duct.
Click to expand...
Do duct silencers work? I have my fan setup inside my tent mostly because outside of the tent it is noisy. I'd like to place the fan on the roof of the tent with just the filter inside. I'm exhausting out a window so I can't place the filter at the end of the duct run.

I saw a video from a fan company talking about filter placement. They demonstrated how attaching the filter to the incoming side messes up the air flow and doesn't utilize the entire filter. They're suggestion was to place the fan, open mouthed, inside the tent or, better yet, at one of the ports and the filter at the end of the duct run for better filter utilization.

I count five 90* turns in my ducting. If I reduce the amount of turns will this increase the CFM the fan is able to produce along with reducing back pressure?

Flexible ducting has ridges in it. Will smooth ducting help increase airflow and reduce back pressure?

I have a T6 fan in my 5 x 5 tent that is rated at 406 CFM. I'm assuming this number is at full bore. I've noticed it is in high to full mode a lot of the time. I'm wondering if my ducting is impeding the fans performance. I've been thinking about upgrading to an T8 so that the fan doesn't have to work so hard but if the problem is me impeding the performance through my duct install then I would rather try and optimize that first before moving up to a bigger fan.

Is it better to run an arc than a 90* turn if I have to make a turn? If 90* adds 10ft what does a 45* turn add?
 
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Rootsruler said:
Do duct silencers work? I have my fan setup inside my tent mostly because outside of the tent it is noisy. I'd like to place the fan on the roof of the tent with just the filter inside. I'm exhausting out a window so I can't place the filter at the end of the duct run.

I saw a video from a fan company talking about filter placement. They demonstrated how attaching the filter to the incoming side messes up the air flow and doesn't utilize the entire filter. They're suggestion was to place the fan, open mouthed, inside the tent or, better yet, at one of the ports and the filter at the end of the duct run for better filter utilization.

I count five 90* turns in my ducting. If I reduce the amount of turns will this increase the CFM the fan is able to produce along with reducing back pressure?

Flexible ducting has ridges in it. Will smooth ducting help increase airflow and reduce back pressure?

I have a T6 fan in my 5 x 5 tent that is rated at 406 CFM. I'm assuming this number is at full bore. I've noticed it is in high to full mode a lot of the time. I'm wondering if my ducting is impeding the fans performance. I've been thinking about upgrading to an T8 so that the fan doesn't have to work so hard but if the problem is me impeding the performance through my duct install then I would rather try and optimize that first before moving up to a bigger fan.

Is it better to run an arc than a 90* turn if I have to make a turn? If 90* adds 10ft what does a 45* turn add?
Click to expand...
Flexible hose as much as possible when not straight rigid will increase air flow.
I have no clue with air but in water a 90 is equal to 1 foot of head pressure.
That means the 90 is the same as pumping the water 1 foot above the pump nozzle.
5 90s could really reduce air flow IMO. Flex hose or even 45s as you mention will be better than 90s.
 
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steamroller said:
Flexible hose as much as possible when not straight rigid will increase air flow.
I have no clue with air but in water a 90 is equal to 1 foot of head pressure.
That means the 90 is the same as pumping the water 1 foot above the pump nozzle.
5 90s could really reduce air flow IMO. Flex hose or even 45s as you mention will be better than 90s.
Click to expand...
We have someone here that does estimating in the hvac field can't remember who. If he doesn't mind maybe @Moe.Red can put a hvac below his name
 
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steamroller said:
Flexible hose as much as possible when not straight rigid will increase air flow.
I have no clue with air but in water a 90 is equal to 1 foot of head pressure.
That means the 90 is the same as pumping the water 1 foot above the pump nozzle.
5 90s could really reduce air flow IMO. Flex hose or even 45s as you mention will be better than 90s.
Click to expand...
The ducting I have is all flex hose but I have 90* turns to get it to the window I use to exhaust. I can reduce some of the turns to 45* but next run I'll need to position the tent so that the exhaust port is nearest to the window so that I get a straight shot at it with the least amount of 90's and the shortest duct path.
 
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Rootsruler said:
Do duct silencers work? I have my fan setup inside my tent mostly because outside of the tent it is noisy. I'd like to place the fan on the roof of the tent with just the filter inside. I'm exhausting out a window so I can't place the filter at the end of the duct run.

I saw a video from a fan company talking about filter placement. They demonstrated how attaching the filter to the incoming side messes up the air flow and doesn't utilize the entire filter. They're suggestion was to place the fan, open mouthed, inside the tent or, better yet, at one of the ports and the filter at the end of the duct run for better filter utilization.

I count five 90* turns in my ducting. If I reduce the amount of turns will this increase the CFM the fan is able to produce along with reducing back pressure?

Flexible ducting has ridges in it. Will smooth ducting help increase airflow and reduce back pressure?

I have a T6 fan in my 5 x 5 tent that is rated at 406 CFM. I'm assuming this number is at full bore. I've noticed it is in high to full mode a lot of the time. I'm wondering if my ducting is impeding the fans performance. I've been thinking about upgrading to an T8 so that the fan doesn't have to work so hard but if the problem is me impeding the performance through my duct install then I would rather try and optimize that first before moving up to a bigger fan.

Is it better to run an arc than a 90* turn if I have to make a turn? If 90* adds 10ft what does a 45* turn add?
Click to expand...
I don't really have any experience with duct silencers so not sure how effective it would actually be.

As far as the filter being on outgoing vs. incoming generally speaking it's more effective to pull air through an object than push it. This is why the air blows out the top of an AC unit vs. pulling in through the fan & blowing out the coils. Trying to push the air out the coil can lead to a lot of turbulence & certain areas of the coil getting more airflow than others. By creating a negative pressure inside the coil space we get more even airflow over the coil & I would assume a filter would work the same.

Yes any 90's will add restriction, but it's the equivalent of 5 feet, the 10 foot example was for a u bend. A 45 would be 2.5 feet. Wider radius turns restrict less than tight turns. And yes smooth duct does restrict slightly less than flex duct. Although I don't have an exact number as far as how much restriction it actually adds, I don't think it's a huge thing. I know that for HVAC we use the same size pipe whether it's flex or rigid.

The rating on your fan I'm sure is wide open with no duct attached to it. So as you add filters, lengths of pipe, bends & any kind of baffles or backflow prevention all reduce that number. So a 400 cfm fan with all that stuff attached to it may only put out 300 cfm.
 
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Scotty 420 said:
I don't really have any experience with duct silencers so not sure how effective it would actually be.

As far as the filter being on outgoing vs. incoming generally speaking it's more effective to pull air through an object than push it. This is why the air blows out the top of an AC unit vs. pulling in through the fan & blowing out the coils. Trying to push the air out the coil can lead to a lot of turbulence & certain areas of the coil getting more airflow than others. By creating a negative pressure inside the coil space we get more even airflow over the coil & I would assume a filter would work the same.

Yes any (0's will add restriction, but it's the equivalent of 5 feet, the 10 foot example was for a u bend. A 45 would be 2.5 feet. Wider radius turns restrict less than tight turns. And yes smooth duct does restrict slightly less than flex duct. Although I don't have an exact number as far as how much restriction it actually adds, I don't think it's a huge thing. I know that for HVAC we use the same size pipe whether it's flex or rigid.

The rating on your fan I'm sure is wide open with no duct attached to it. So as you add filters, lengths of pipe, bends & any kind of baffles or backflow prevention all reduce that number. So a 400 cfm fan with all that stuff attached to it may only put out 300 cfm.
Click to expand...
This is must know info for us all.
Thanks so much Scotty~!:cool:
 
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Rootsruler said:
Why do you need a booster fan? I run the T6 in my 5 x 5 and it exchanges plenty of air.

I have the exhaust fan mounted on the roof of the tent sucking air out while the bottom vents flow air into the tent and up through the canopy.

In case you don't know you want 3 air exchanges a minute minimum in your tent. Mine is a 5' x 5' x 6.5'. That gives me 162.5 cubic feet of space. I have the same ACI T6 you have. It maxes at 402 cfm. 162.5 x 3 = 487.5 cfm. I need a bigger fan. I'm looking at the T8 as a replacement. It puts out 807 cfm.
Click to expand...
Is this 3x every 1 minute accurate? Everything I have looked up on it says 1 time every 5 mins is enough....

I'd like to know definitively for sure. Mine exchanges roughly once every 4 mins.....haven't seen any issue
 
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Scotty 420 said:
I don't really have any experience with duct silencers so not sure how effective it would actually be.

As far as the filter being on outgoing vs. incoming generally speaking it's more effective to pull air through an object than push it. This is why the air blows out the top of an AC unit vs. pulling in through the fan & blowing out the coils. Trying to push the air out the coil can lead to a lot of turbulence & certain areas of the coil getting more airflow than others. By creating a negative pressure inside the coil space we get more even airflow over the coil & I would assume a filter would work the same.

Yes any 90's will add restriction, but it's the equivalent of 5 feet, the 10 foot example was for a u bend. A 45 would be 2.5 feet. Wider radius turns restrict less than tight turns. And yes smooth duct does restrict slightly less than flex duct. Although I don't have an exact number as far as how much restriction it actually adds, I don't think it's a huge thing. I know that for HVAC we use the same size pipe whether it's flex or rigid.

The rating on your fan I'm sure is wide open with no duct attached to it. So as you add filters, lengths of pipe, bends & any kind of baffles or backflow prevention all reduce that number. So a 400 cfm fan with all that stuff attached to it may only put out 300 cfm.
Click to expand...
In the video I saw they did a smoke test. They attached the filter to the intake side of the fan and added smoke to monitor air flow. You could see that most of the smoke entered the filter from the point closest to the mouth of the fan and utilized around 1/3 of the filter. Almost no smoke entered the other 2/3's of the filter. They then attached the filter to the exhaust side of the fan and added smoke and you could see the entire filter being utilized. They also mentioned something about airflow dynamics around the intake side of the fan being better without the filter attached as it somehow messed up the airflow pattern in a detrimental way.

I also read about how adding a rounded edge to the intake port in the fan housing evened out the airflow better than just a sharp edge.
 
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Rootsruler said:
In the video I saw they did a smoke test. They attached the filter to the intake side of the fan and added smoke to monitor air flow. You could see that most of the smoke entered the filter from the point closest to the mouth of the fan and utilized around 1/3 of the filter. Almost no smoke entered the other 2/3's of the filter. They then attached the filter to the exhaust side of the fan and added smoke and you could see the entire filter being utilized. They also mentioned something about airflow dynamics around the intake side of the fan being better without the filter attached as it somehow messed up the airflow pattern in a detrimental way.

I also read about how adding a rounded edge to the intake port in the fan housing evened out the airflow better than just a sharp edge.
Click to expand...
It may have to do with exact way the hepa filters are designed/shaped or possibly even just that we aren't pulling a low enough negative pressure to use the whole filter. I will say that mine is hooked to the negative side the fan & the pre filter seems to be getting dirty pretty evenly across
 
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With water pumps any throttling should be done after the pump.
One reason is better intake , the second is the pump may over heat or possibly have a shortened life with flow being restricted from intake.
IMO with air the filter has equal restriction at either end? I may not see this clear though?
The fact you only see 1/3 of the filter being used is more a statement on the fans CFM IMO.
As the filter clogs the fresher parts will have equal draw until complete cleaning is needed. The filter only uses what it needs to allow max flow.
I have never used a filter on my fans.
I have 2 AC 6 inch I run in series blowing in and one 8 inch with 6ft of metal duct and one 90 blowing out.
Intake and outtakes on their own control.
 
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Rootsruler said:
I also read about how adding a rounded edge to the intake port in the fan housing evened out the airflow better than just a sharp edge.
Click to expand...
Question id like clarification on.

I've read that adding a 8" to 6" adapter to the intake side of the 6" fan will increase the fans capacity? True or false?
 
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smoke said:
Question id like clarification on.

I've read that adding a 8" to 6" adapter to the intake side of the 6" fan will increase the fans capacity? True or false?
Click to expand...
Definitely false, there is a max cfm a certain size of pipe can carry at a given static pressure. A smaller duct will never give you more air. If you put a 8 to 6 reducer on the outgoing side the air will blow with more velocity but there's a difference between velocity & capacity (or volume)

OK I realized I read that wrong, I can't imagine an 8 to 6 on the end of a 6 inch fan would do anything, it would be interesting to see it tested with a cfm meter
 
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MDK said:
@Scotty 420 can you say anything on the exchange rate necessary? Thanks
Click to expand...
Honestly there's no reason in the normal ventilation world that you ever need that much air exchange. The reason you often hear that I think has more to do with the CO2 needs of the plants. Which quite frankly given our relative levels of experience I feel kinda out of my depth telling you about the needs of the plants as I'm still very much learning that myself.

However what I will say is I find it hard to believe plants use up carbon dioxide at a rate of anywhere close to depleting an entire tent three times in a minute. I will also say that most people I know of that have EC exhaust fans run them at 10% & only ramp up when the tent gets too hot or humid. So running their fans at 10% the vast majority of the time there's no way people are actually getting that exchange rate other than an overheat situation. Which means most of the times there plants are living with a much lower exchange rate. Up until a few days ago my exhaust hasn't been on constant at all, it only came on due to high humidity really. My plants seemed to grow fine with no ventilation most of the time.
 
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Take this for it is worth.
Sorry if already posted;

Ventilation 101 - How to Ventilate Your Grow Space

Ventilation is a vital factor in your plant growth. By supplying fresh air from outside your grow tent, you provide CO2 for your plants, driving their photosynthesis. Expelling the air inside will keep temperature and moisture build-up under control, preventing mold and mildew from inhibiting...
acinfinity.com acinfinity.com
 
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Right on, I got a local buddy his grow is behind mine...my fan runs 4 mins on 2 mins off at the moment on a 24/7 schedule like that. His is set based on temperature which I was weary of but so far it seems to be fine.

Trying to learn where I can dial back to cut costs
 
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