Fans for intake/exhaust

J

jsgrowsalot

Member
I was thinking of just buying some computer fans and spliceing the wire with a power cord then plugging that into the power strip. I do this because i can get 2 120mm fans for $20 this way. Are there cheap intake/exhaust fans that already have a 2/3-prong power socket?
 
Are those cheap fans ac or dc? Most are dc and if they are you can't just splice and plug them in, you need a converter like on your cell phone charger cord.
 
its 12 vdc.so it will need a transformer- a search on this site will find lots of posts detailing power supplies & wiring.
PC fans move a lot of air if free flowing but the cfm drops fast if anything (filters,bends in ventpipe)blocks the flow.
 
Ok I have a question..

How many 120mm pc fans could I power safely with a standard household outlet with power strips, etc.
Thanks
 
Ok I have a question..

How many 120mm pc fans could I power safely with a standard household outlet with power strips, etc.
Thanks
 
mrmadcow said:
its 12 vdc.so it will need a transformer- a search on this site will find lots of posts detailing power supplies & wiring.
PC fans move a lot of air if free flowing but the cfm drops fast if anything (filters,bends in ventpipe)blocks the flow.
Click to expand...
awesome thank you, there will not be any tubing but i will have filters on them. but they are 133cfm. even if it gets cut in half thats 66-67cfm and thats a good amount of airflow still. i will most likely have 3. 1 intake at the bottom, 1 intake on the bulb, and 1 exhaust possibly 2 at the top. all with filters.
 
jsgrowsalot said:
awesome thank you, there will not be any tubing but i will have filters on them. but they are 133cfm. even if it gets cut in half thats 66-67cfm and thats a good amount of airflow still. i will most likely have 3. 1 intake at the bottom, 1 intake on the bulb, and 1 exhaust possibly 2 at the top. all with filters.
Click to expand...
depending on the filter,you could cut 90% of the flow.PC fans are not made to deal w/ any resistance.
why use fans on the intake? passive intakes work fine & you could use all 3 (or4) as exhaust

adam5150 said:
Ok I have a question..How many 120mm pc fans could I power safely with a standard household outlet with power strips, etc...Thanks
Click to expand...
hundreds- they only draw 4-5 watts so if you have the correct transformers,ect......
 
drawing watts has nothing to do with how many it can use. watts is what it will cost you to run it,. its amps we need to watch to blow curcuits. and it is many as its in milli amps and very low amps.
what do you plan on cooling with tiny little pc fans that dont do hardly anything. maybe 1 or 2 cfl is about all they will do good for. youd be better of if cash is an issue using an inline duct fan booster. cost is about 30 buck, plugs to wall outlet
 
mrmadcow said:
depending on the filter,you could cut 90% of the flow.PC fans are not made to deal w/ any resistance.
why use fans on the intake? passive intakes work fine & you could use all 3 (or4) as exhaust
Click to expand...
because I want fresh air in the cabinate grow. it will be closed and not big at all. 18-22" wide, 14-18" long, 50-60" tall. only need it for one plant
 
not using an intake is a better way to go id say. unless maybe this pc fan is to small to create negative pressure in the room. then you need an intake to push the air in. the pc fan may be to small to create this., no neg pressure no fresh air coming in then and smells escape. even a bathroom fan is a better choice than a pc fan.
 
ok ok then. the fan isnt that small. 120mm its like 4" wide. I build PCs and those PC fans DO move ALOT of air. I have 1 with half the airflow and that moves alot of air. But Im just sayin dont down PC fans. This in weed growing though, not computer building. You guys know more than me. I can get a bathroom fan like at Lowes or Walmart right?
 
im nit dissin pc fans. nor your idea. they die real fast as soon as you add any restriction to them right,. using in this fashion is a big restriction. been there. they are ok to help boost air flow or for a small room that needs a bit of help at the intake end. 120 mm dont realy tell us the cfm it can draw...not blow as they are more meant to do....needs to suck the air out.
 
it has 133cfm but i saw like a 5" fan at WM today that would be perfect. and already has a wall cord so no splicing :)
and if it changes anything at all i planned on putting the exhaust from an air purifier right next to the intake fan (if i have an intake) for the cab.
 
Medi 1 said:
drawing watts has nothing to do with how many it can use. watts is what it will cost you to run it,. its amps we need to watch to blow curcuits. and it is many as its in milli amps and very low amps.
Click to expand...

the wattage drawn is directly related to how many fans you can run on a circuit.read up on ohms law.watts divided by volts=amps so if a fan draws 5 watts @ 12vdc,it will draw .4 amps at 12 vdc,you can put 2 fans on a transformer that puts out 1 amp at 12vdc. the transformer will draw about .095 amps at 115 vac. .0869 in a perfect world but a transformer will use/lose a few watts in the conversion.

Medi 1 said:
what do you plan on cooling with tiny little pc fans that dont do hardly anything. maybe 1 or 2 cfl is about all they will do good for. youd be better of if cash is an issue using an inline duct fan booster. cost is about 30 buck, plugs to wall outlet
Click to expand...
I have a room running a 600 watts HPS, its 32x44x80 high. light is in a homemade coltube using 2 pc fans(1 pushing,1 pulling through about 6 feet of 4 in ducting) and another 3 fans to pull the air from the grow to an adjoining room where a ozone generator runs 15 min every hour and 2 more to draw the air out of that room to the outside. all on a 7 amp 12vdc power supply.when lights are on,all fans run but when lights go off,only 2 fans draw from the grow room & 1 from the filter room.I also have a bath fan attached to a thermostat set for 85 but it will only kick on if outside temps are above 85.


jsgrowsalot said:
because I want fresh air in the cabinate grow. it will be closed and not big at all. 18-22" wide, 14-18" long, 50-60" tall. only need it for one plant
Click to expand...
again passive intake will be fine, if the fans are pulling air out of the box,fresh air will be drawn in.just make a vent at the bottom(filtered) and place the fans at the top sucking out.
 
ya...so mr cow you have multi fans doing the job that 1 real one will do many times over. and yes i know the ohms law thing,.im trying to keep things more simple to help out was all.
so on average what does one of them fans cost to buy new...30 buk or so??...so 56 x 30 is 150 bucks. can get a real nice inline for that cost and way way more cfm`s.
like you posted you even need 2 fans just to move air 6 foot through the tubes.

js, yes i get they may claim those cfm but in my opinion that is more a blowing cfm rather than drawing as inlines do. or they wouldnt bother with the housing and make em cheaper to. those are there for a reason
 
Medi 1 said:
so on average what does one of them fans cost to buy new...30 buk or so??...so 56 x 30 is 150 bucks.....like you posted you even need 2 fans just to move air 6 foot through the tubes.
Click to expand...
if you went to buy them yes,I scavaged them for free ;) dont know if I NEEDED 2 but they were free &better safe than sorry
Medi 1 said:
yes i get they may claim those cfm but in my opinion that is more a blowing cfm rather than drawing as inlines do.
Click to expand...
agreed, they may put out that much freeflowing but add a restriction....
 
home depot or lowes has the bathfans and if u spend more u can get one that moves 90 cfm instead of the standard 50 cfm

QUOTE=jsgrowsalot;4685981]ok ok then. the fan isnt that small. 120mm its like 4" wide. I build PCs and those PC fans DO move ALOT of air. I have 1 with half the airflow and that moves alot of air. But Im just sayin dont down PC fans. This in weed growing though, not computer building. You guys know more than me. I can get a bathroom fan like at Lowes or Walmart right?[/QUOTE]
 
ive seen them bath fans 150 cfm even. bit more cost but small enough. and may not officialy move the full rated cfm but it is more than a reg one, or duct booster fans, muffin fans that are made for this type of application. high heat and humidity will kill them pc fans. just some thoughts.
 
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