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The ultimate beginner's guide to PC FANS
- Thread starter ScrubNinja
- Start date
Igotyourback
Member
Great Info Thanks
Glad to help, Igotyourback, good luck. I was thinking about how you just described it MJ, and it's the same principle if I'm picturing it correctly.
Sorry to keep going on about it but there's the potential for failure if you're making a filter without understanding pressure....there's also the potential to luck your way through it
But I figure it's best to just understand it. So this is for anyone still interested:
Think of a bottle of pasta sauce. You guys have that little button thing molded into the lid right? When you unscrew it, it pops out. Before that moment, negative pressure was holding it in so no air was escaping out. Then think of a balloon - high positive pressure and if you break the seal, air leaks out. After a few days your balloon is deflated anyway because the air has leaked out through the microscopic pores in the rubber, or the gaps in the knot you tied, which seemed like such a tight seal. That's all it comes down to. I always picture the seperate elements in the flow and think "what would happen if this duct tape came loose or isn't sealed right?". If you do this and everything passes you should have close to a fail-free system. Some bits will screw up if they did leak of course, but you can minimize/optimize any risk.
Sorry to keep going on about it but there's the potential for failure if you're making a filter without understanding pressure....there's also the potential to luck your way through it
But I figure it's best to just understand it. So this is for anyone still interested:Think of a bottle of pasta sauce. You guys have that little button thing molded into the lid right? When you unscrew it, it pops out. Before that moment, negative pressure was holding it in so no air was escaping out. Then think of a balloon - high positive pressure and if you break the seal, air leaks out. After a few days your balloon is deflated anyway because the air has leaked out through the microscopic pores in the rubber, or the gaps in the knot you tied, which seemed like such a tight seal. That's all it comes down to. I always picture the seperate elements in the flow and think "what would happen if this duct tape came loose or isn't sealed right?". If you do this and everything passes you should have close to a fail-free system. Some bits will screw up if they did leak of course, but you can minimize/optimize any risk.
oldone
Member
I have been thinking about this all day...
As usual you make your case well. Your 376 sq in vs my 150 explains a lot. You must be devoting 15-20% of your grow space to it. Thats impressive. You mention later that my design could cause settling of the AC. I thought about that and planned to block off any small area thus exposed. It also occurred to me that your massive filter may be susceptible to the same thing.
I really want to keep the drying chamber and I need lots of room for electrical stuff. My cab is mostly cut, glued and screwed together so I am stuck with the basic design you have seen.
I did leave room for 2 120mm fans however. So is it better to stack fans or have them in tandem? (I'm kinda stuck to the vent pattern already built)
I have read the stacking fan posts and have seen others asking about counter rotating fans. There are a few aircraft that fly today using 2 props (close together) on the same shaft. They are *always* counter rotating. There is even a helicopter that does this.
I'll get you to critique my new design if I may when its finished.
Thanks as always,
OO
It goes into and up a wall cavity into the furnace room. I think a noisy ceiling fan will suddenly appear in there.
Good idea...damn...revision 2 coming up
As usual you make your case well. Your 376 sq in vs my 150 explains a lot. You must be devoting 15-20% of your grow space to it. Thats impressive. You mention later that my design could cause settling of the AC. I thought about that and planned to block off any small area thus exposed. It also occurred to me that your massive filter may be susceptible to the same thing.
I really want to keep the drying chamber and I need lots of room for electrical stuff. My cab is mostly cut, glued and screwed together so I am stuck with the basic design you have seen.
I did leave room for 2 120mm fans however. So is it better to stack fans or have them in tandem? (I'm kinda stuck to the vent pattern already built)
I have read the stacking fan posts and have seen others asking about counter rotating fans. There are a few aircraft that fly today using 2 props (close together) on the same shaft. They are *always* counter rotating. There is even a helicopter that does this.
I'll get you to critique my new design if I may when its finished.
Thanks as always,
OO
Sure thing dude, I'd love to see it and glad I could put a new slant on it.
Yeah it was just a last minute thing. I smoke too much weed and had that plant in a dodgy temporary setup with a light leak and no carbon filter. So I snapped out of my haze and threw that together. I could easily set it all up outside the cab and still have everything work smooth by following ye olde pressure principles, I just don't need the room.
Does not compute. Blocking off area is the wrong approach when you need the most possible in my opinion. I agree though that it's a decent compromise, being that it's a thin sliver. But I guess you see what I mean.
I *think* this is for my filter, otherwise they may use a similar method, but there is a ring of compressed rubber or something that expands to take up the slack caused by settling. And any quality filter is going to be shaken well. You know in a paint shop they stick a can of paint in a thing and it shakes and shakes it for hours. Similar thing happens with commercial filters. We can tap it for a few minutes, or even spend most of a day doing it, but we'll never get as good as a professional shake-down, I suspect.
Not sure where you left room, but overall I'd say you still have a lot of possibilities for the placement. Stacking/tandem depends on the cab's needs. If highest pressure is needed, stack them with a space between them (and preferably an angle or something that otherwise breaks the circular flow, imo, if a cab has this anyway...A long individual post would be needed to explain this fully). You should have considerably more pressure with those fans compared to a thermaltake so I think if you focus on getting that filter area huge, you could have the fans side by side, to give you more cfm. What kind of surface area would you be looking at if you broaden out? Also, just so you know, I am hopeless at cubic feet so sort of guessing the dimensions of your cab a little.
Counter rotating fans, or even stacking fans with a space, is a bit of a black art in my opinion. The main problem with CR is that you will need two fans exactly the same but one spinning opposite direction with blades reversed. Good luck but I don't think they exist. Certainly would be lucky to find decent fans that will suit. And then, do you need them exact same power? If you read up on it, you will quickly see that nobody has any idea, it's all just theorizing and book learnin'. It's science. I have no idea either. But basically the problem is finding the fans and dealing with laws of physics.
So anyway, to stop typing and have a smoke...let's say you are gonna stack the fans or whatever you want to roll with, where do you think they will fit in well?
Yeah it was just a last minute thing. I smoke too much weed and had that plant in a dodgy temporary setup with a light leak and no carbon filter. So I snapped out of my haze and threw that together. I could easily set it all up outside the cab and still have everything work smooth by following ye olde pressure principles, I just don't need the room.
Does not compute. Blocking off area is the wrong approach when you need the most possible in my opinion. I agree though that it's a decent compromise, being that it's a thin sliver. But I guess you see what I mean.
I *think* this is for my filter, otherwise they may use a similar method, but there is a ring of compressed rubber or something that expands to take up the slack caused by settling. And any quality filter is going to be shaken well. You know in a paint shop they stick a can of paint in a thing and it shakes and shakes it for hours. Similar thing happens with commercial filters. We can tap it for a few minutes, or even spend most of a day doing it, but we'll never get as good as a professional shake-down, I suspect.
Not sure where you left room, but overall I'd say you still have a lot of possibilities for the placement. Stacking/tandem depends on the cab's needs. If highest pressure is needed, stack them with a space between them (and preferably an angle or something that otherwise breaks the circular flow, imo, if a cab has this anyway...A long individual post would be needed to explain this fully). You should have considerably more pressure with those fans compared to a thermaltake so I think if you focus on getting that filter area huge, you could have the fans side by side, to give you more cfm. What kind of surface area would you be looking at if you broaden out? Also, just so you know, I am hopeless at cubic feet so sort of guessing the dimensions of your cab a little.
Counter rotating fans, or even stacking fans with a space, is a bit of a black art in my opinion. The main problem with CR is that you will need two fans exactly the same but one spinning opposite direction with blades reversed. Good luck but I don't think they exist. Certainly would be lucky to find decent fans that will suit. And then, do you need them exact same power? If you read up on it, you will quickly see that nobody has any idea, it's all just theorizing and book learnin'. It's science. I have no idea either. But basically the problem is finding the fans and dealing with laws of physics.
So anyway, to stop typing and have a smoke...let's say you are gonna stack the fans or whatever you want to roll with, where do you think they will fit in well?
oldone
Member
Its seems to me that the expanding foam is blocking flow as well...
I'm thinking about a 20x20 horizontal scrubber placed above tandem mounted fans. The fans will be speed controlled and I want the scrubber to act as a muffler as well. I'm kinda worried about filter sag but I have a few ideas.
The kicker is the electronics; gfci socket, power bar, 3 timers, 3 ballasts, 12 volt power supply and fan controller. This will have to go on a shelf above the scrubber I think. I need a smoke and some serious sketchup time.
FYI I have about 15 cu ft of space.
Thanks,
OO
Well thanks for clearing that up, lol.
Sure but it has a lot of area to lose and half an inch or so (totally guessing) isn't going to break the bank in return for the safety it offers. And it shouldn't settle as much, as mentioned.
Well, can't wait to see what happens next.
Edit: forgot to say your plan sounds great so far.
For the sag I recommend using a wire rack like you see in mine, and go to a hardware store and they sell little holders that hold the wire mesh off the ground when they lay the cement slab for a house. They are sort of like the little things you get in pizza boxes to stop the centre collapsing.
Edit: This is what I mean. And in action.
Edit: This is what I mean. And in action.
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They install that smoke at the factory and once you let the factory smoke out it quits working.
oldone
Member
Sorry dude, it was late...
My cab is
f: 32.125h x 26.875w x 23.25d 4.9 sft 11.6 cuft
v: 23.755h x 11.25w x 23.25d 1.8 sft 3.6 cuft
or:
f: 815h x 682w x 590d .40 sq m .32 cu m
v: 603h x 285w x 590d .14 sq m .19 cu m
I have changed the design (374 sq in filter!) and want you to have a look at it but I dont want to clutter up your excellent fan thread. Shall I start an new thread or just post here?
Thanks,
OO
Thanks. I've no objections to do it here. I think it's educational for everyone
oldone
Member
Here is an overall view with lights and the E&F system in place:
I have left off the angled top for clarity.
This is the new filter with the electric shelf above it.
I will have to play with the height of the filter case to balance the area above it and the area below it.
Here is where the fans will gopoor labels...sigh)
yeah I know they are pushing into the filter instead of pulling... You convinced me to go with separate fans for flower and veg so the 3 vents between the flower and veg will be blocked..
Now I have to pick new fans. What kind of static pressure should I be looking for? Also all of the exhaust fans are mounted horizontally so they should have ball bearings. That cuts my choices down a lot. Any suggestions?
I am concerned that the fans will be blowing onto the filter surface from only 50 or 75 mm away. Do you think this is an issue?
Thanks,
OO
I have left off the angled top for clarity.
This is the new filter with the electric shelf above it.
I will have to play with the height of the filter case to balance the area above it and the area below it.
Here is where the fans will go
poor labels...sigh)yeah I know they are pushing into the filter instead of pulling... You convinced me to go with separate fans for flower and veg so the 3 vents between the flower and veg will be blocked..
Now I have to pick new fans. What kind of static pressure should I be looking for? Also all of the exhaust fans are mounted horizontally so they should have ball bearings. That cuts my choices down a lot. Any suggestions?
I am concerned that the fans will be blowing onto the filter surface from only 50 or 75 mm away. Do you think this is an issue?
Thanks,
OO
This looks really good bro. I'm not dead certain on the pressures but I think the Deltas you mentioned seems like a great choice.
With the filter distance I would keep it at least 2.5" (6cm) from the top of your fans or their hole leading into the carbon chamber. This should allow enough space to "breathe". I work this out with that page I always link. Just using circumference and the height. 37.7cm circumference x 6cm height = 226.2sq cm. Twice the area provided by a 12cm hole. So it's not entirely accurate, but it's a safe number imo.
With the filter distance I would keep it at least 2.5" (6cm) from the top of your fans or their hole leading into the carbon chamber. This should allow enough space to "breathe". I work this out with that page I always link. Just using circumference and the height. 37.7cm circumference x 6cm height = 226.2sq cm. Twice the area provided by a 12cm hole. So it's not entirely accurate, but it's a safe number imo.
Btw here is that damn link to sort through the Deltas. These are the 120mm 12v's. If you click on the column headers you can sort them by that spec. I was talking about this a few pages back so here it is. Edit: gah I'm not sure that that is even working...blah. I give up.
Okay try this.
Okay try this.
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R
Rhyolite
Post erased.
Cheers
Cheers
You would be very wise to "clone" red He goes into a lot of details for the important things and clearly knows what he's doin'.
Humidity
Well, as you may have guessed, I have some strange views on things and one of them is humidity. I live in a tropical zone and it's often an issue.
People will tell you you're doomed if you have high humidity but I haven't found that to be the case. In fact, I've never had a serious mould problem indoors or outdoors. I was freaking out because on my first indoor flowering, the humidity was >85%! Certain peril according to what you'll read on here so I started this thread and to cut a long story short, Pharma Geddon was exactly right.
I just wanna say that I understand anyone being skeptical because I mentioned it to my friend and he had a hard time believing me. 2 people is not 100% proof, but I pity anyone who doesn't follow that advice in a high humidity situation. My friend was like "I'll just blow lots of air around inside the cab" which is what everyone on here will tell you, but imo that's guff. Everyone has tried that and it's no guarantee to not get mould. I had one circulation fan in a whole tent and there was a lot of areas not getting any airflow once the screen and buds filled out. I added another small one later under the screen but still had a lot of buds with no active airflow. No mould. >85 rh. You be the judge.
Well that's my rant for the day
Always keep your intakes as big as possible without letting smelly air leak out. You can run a dehumidifier, that will absolutely solve your problem (but I couldn't run one), or you can dick around with moisture eaters (total waste of time, don't bother), or you can make your intakes large (also makes your system run better - ding ding ding), or you can install intake fans (I'm not sure how correct Pharma was about "lack of positive pressure" so considering all things, I think larger intakes are the best approach).
I can be proven wrong on any of this btw, it's just what I've seen to be true from my own experiences.
I am at 59% rh right this minute in the cab and that's the lowest I've ever noticed it. I'm sure that's probably still over the recommended levels. I can't remember what they were exactly but just do a thread title search for humidity.
A fan in itself won't change the humidity as far as I'm aware. It just blows it around. Your humidity will be in the range of the air you are pulling into your cab, probably higher with the plant breathing everywhere.
Cheers
You would be very wise to "clone" red
He goes into a lot of details for the important things and clearly knows what he's doin'.Humidity
Well, as you may have guessed, I have some strange views on things and one of them is humidity. I live in a tropical zone and it's often an issue.People will tell you you're doomed if you have high humidity but I haven't found that to be the case. In fact, I've never had a serious mould problem indoors or outdoors. I was freaking out because on my first indoor flowering, the humidity was >85%! Certain peril according to what you'll read on here so I started this thread and to cut a long story short, Pharma Geddon was exactly right.
I just wanna say that I understand anyone being skeptical because I mentioned it to my friend and he had a hard time believing me. 2 people is not 100% proof, but I pity anyone who doesn't follow that advice in a high humidity situation. My friend was like "I'll just blow lots of air around inside the cab" which is what everyone on here will tell you, but imo that's guff. Everyone has tried that and it's no guarantee to not get mould. I had one circulation fan in a whole tent and there was a lot of areas not getting any airflow once the screen and buds filled out. I added another small one later under the screen but still had a lot of buds with no active airflow. No mould. >85 rh. You be the judge.
Well that's my rant for the day
Always keep your intakes as big as possible without letting smelly air leak out. You can run a dehumidifier, that will absolutely solve your problem (but I couldn't run one), or you can dick around with moisture eaters (total waste of time, don't bother), or you can make your intakes large (also makes your system run better - ding ding ding), or you can install intake fans (I'm not sure how correct Pharma was about "lack of positive pressure" so considering all things, I think larger intakes are the best approach).I can be proven wrong on any of this btw, it's just what I've seen to be true from my own experiences.
I am at 59% rh right this minute in the cab and that's the lowest I've ever noticed it. I'm sure that's probably still over the recommended levels. I can't remember what they were exactly but just do a thread title search for humidity.
A fan in itself won't change the humidity as far as I'm aware. It just blows it around. Your humidity will be in the range of the air you are pulling into your cab, probably higher with the plant breathing everywhere.
R
Rhyolite
Post erased.
Hey bro it depends on your needs I guess, but that doesn't seem like a very spectacular fan. 38cfm is very low, and that's on high speed? But like I say, it depends on your needs. I think that is what red used so you will be good to go if you copy him. I was just thinking something like the smart fan II would be a better choice. You get like 110cfm and a speed dial so you can still slow it down to 38cfm and be silent, but on a hot day, you can have nearly 3 times the cfm if you want it. Just thought I'd mention. Peace.
