DIY Hood Fans

[cmsurfr22]

I wanted to put some fans in my AGA Hood but i didn't want to spend too much on fans made specifically for aquariums. So here is an alternative to using aquarium fans:

i got 2 of these computer case fans

and i got 1 of these ac-dc adapter


you can play around with the number of fans but you just need to know a few electrical things.

1. computer fans run on 12 volt DC power
2. the outlets in your house provide 110 volt AC power
3. volts are not shared but amps are

so....with that you need the ac to dc converter to convert the 110v ac power from the outlet to the 12v dc power needed by the computer fans.

radio shack has up to 1500 mA (milliamps) and the fans i got from antec run on .24 amps (240 mA) which i got from their website. so in theory you could put up to 6 of those fans on that ac adapter. i chose the 1000 mA adapter so i could fit up to 4 fans. All you need to do is cut off the plug on the end of the ac-dc adapter and the case fans and wire up the fans to the adapter and either solder them or twist them and use a cap. if you wire them up backwards then they won't spin so make sure you wire them correctly. to do this i just pluged in the ac-dc adapter and then took the fan wires and touched them to the exposed adapter wires to see which way they went. (WARNING: be careful when you do this as you can get shocked!)

each fan blows 79 CFM so if you have 6 of these that's a lot of air all coming from one outlet. as opposed to the ones made for aquariums that each have their own outlet.

so for 50 bucks i was able to cool my 210 4 degrees with 2 fans.

 

[concept3]

awesome chris!



I did the same thing on my DIY hood, but I bought the fans in ebay and found an AC/DC adapter lying round.



Here is an excerpt how I mounted it to my hood above the reflectors:

<a href=showthread.php?s=&postid=9006949#post9006949 target=_blank>Originally posted</a> by concept3
Worked on the hood last night finishing up on the Ventilation....

After cutting the holes with a dremel, I cleaned up the edges and then placed Felt pads for the corners to hopefully help with the damping. I don't want my hood to act like a guitar.... Vibrating fans will get amplified.... The wire ends were hard wired to a 2 amp 12 Volt AC/DC adapter. The fans are only 0.5amps each, so I could technically throw two more up.

I'll see how these two work for now since it will be an open back.

 

[RichT]

Chris
I did this as well. 3 fans to one adapter. Pretty cheap but a little on the noisy side. Then I took it a step further and plug them into a Ranco Temp Controller. I don't recall if I wired the fans in series or parallel or if it even mattered. You may want to expand on that.

 

[cmsurfr22]

Yeah mine are hooked up to my aquacontroller. they are a bit noisy but from what i understand so is a chiller. i think i wired mine in parallel, i mix series and parallel up, but all of the red wires are connected in the same place and all the black wires are connected in the same place. as opposed to fan 1 red wire is hooked to fan 2 red wire which is hooked to fan 3 red wire, i think that is in series. i'm not sure if it matters or not or what the difference would be if they both worked. maybe a resident electrician might know?

 

[concept3]

series wiring is:

negative to black fan 1.....red fan 1 to black fan 2, and then red fan 2 to black fan 3, then red fan3 positive
if one of the connections come loose, the circuit will get broken, no fans will work (get it i hope?)

parallel is:
all reds to positive
all blacks to positive
you can pull each off the electricity, the rest will still work

 

[cmsurfr22]

ok so why would anyone ever want to do them in series? are there any advantages?

 

[RichT]

I don't believe there is an advantage or even if you would want to do it that way (series). I was figuring for the benefit of others who may be considering doing this, it would be good info.

I just checked what I did and their wired parallel. All the reds together and all the blacks together. HTH

 

[malulu]

in this case you have to do it in pararell...

you can not do it in series, cause if you have 2 FANs in a series, that mean each Fan will only get 110V / 2 ==> 55V.  they will either simply not turning or will turn very slowly.

some time, when stuffs are hookup in series is because they wanted to slow/step down the electric-voltage... like the X'mas light - if all of them were connect as parallel, then each one will get 110V, that mean each ligh bulb will have to be VERY BIG cause they need to accept a greater current/voltage, and by serialized them, it will then divided the voltage to smaller sections to apply to each light bulb... (but the pain is, when one goes out, you will need to spent a freaking hour to find out which one was BAD!!) 

hope this explaination help!

 

[concept3]

-OR-

you wire them in series if you want the fans to run slower (like malulu said) so they don't make noise.

Wiring in series also enables you to use what you have available, for instance, if 4 fans are let's say 1 amp each, and you have a 2 amp AC/DC converter and you wire it in parallel, you would eventually overheat and kill the adapter. Wiring 2 fans in series and the other 2 in series and THEN parallel them together will keep the AC/DC at a stable 2 amperes. The fans will run at half the speeds, be more quieter, but you'll save the adapter from burning since it will not exceed 2 ohms.


(I use to install and design insane car audio systems waaaay back in the day, wiring 2 ohm, 4 ohm and 6 ohm subwoofers in series and parallel to achieve the desired output out of a single 2ohm stable or 4 ohm amplifier)

 

[malulu]

in this case, if you want it to be a little bit quiet-er - you may want to use a lower voltage like 9V or something... then put them all in parallel, but make sure the AC/DC adapter have the enough AMP support all fans.  (if you put them in serial, if one fan break, two fans will stop...)   :

 

[cmsurfr22]

I like the idea of twice as many fans at half the speed. because mine are quite noisy. if i am running two fans in series three times, then it wouldn't matter that if one of the two fans in series died, it would still be as if only one fan had died in my 3 fan system. maybe i'll try this sometime.