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PC Fan Wiring Tutorial

A lot of people have asked me how I wired a PC fan to supply cool air to my HL tank or just so they can cool off their lights so I finally got around to making this tutorial. If you just need to wire a fan for your lights just follow the wiring*. If you need to supply cool air to a HL tank through a duct you'll need to build a mount for the fan, there may be a bunch of ways to accomplish that but this is how I do it.

*I am not an electrician - good luck! :D

First are the parts:

Power supply for a 12V DC computer Fan
If you buy one like this you can run up to 1 AMP worth of fan, the one I will be running is 0.36A. Be sure to buy a sufficiently powerful power supply to run your fan. A cell phone charger might not be powerful enough. This model has variable voltage so I can make my fan run at various speeds. I think I got these off ebay for $9.99 each postage paid.
fan1.jpg


I got my new fan from Radio Shack because they are sturdier than the cheaper all plastic ones but also a bit pricier. This new model they have moves air at 85 CFM it's actually cold in front of it! This fan was $19.98

fan2.jpg


*WHY DON'T I USE ROUND "DUCT FANS"? BECAUSE THEY'RE LOUD!!!


This is the panel the fan will be mounted to so it can blow into the terrarium. The panel can then be mounted or hung where it can gather cool air. This panel is found in the duct work department and is called a 4" Ceiling Collar and was $3.68
fan3.jpg


The other part you need for the fan mount is a 4" Duct Starter Collar and is $2.31
fan4.jpg


Also get a tube of Amazing Household goop glue to glue all the parts together a 3.5 oz tube is $4.57


Begin by putting the Duct Starter Collar into the Ceiling Collar:
fan5.jpg


Now fold down all the tabs as tightly as you can (it'll still be loose):

fan6.jpg


Run a thick bead of Goop around the join of the Duct Starter Collar and the Ceiling Collar, do the tabbed side as well.
fan8.jpg



As the duct starter dries and cures it's time to wire the fan.

Cut the plug off the end of the adapters cord. and strip the last 1/2" or so of the wire covering and twist the positive lead from the power pack (black with white stripe) to the red lead from the fan and the solid black wire on the power supply to the black wire on the fan.


fan9.jpg


keep the positive and negative apart and plug it in if it doesn't move you did it wrong. Unplug it and reverse the connections. If it moves play with the voltage selector and see how it sounds/feels as it speeds up and slows down, then unplug it and move on...

fan11.jpg


If your connections are good go ahead and unplug the power supply and cap the connections - don't skip this step! You WILL start a fire if the uncapped connections should happen to cross.

fan10.jpg


As an extra step I use Gorrilla Grip black duct tape to secure my caps on my connections, they can still come undone over the years and need to be recapped and retaped but it lasts far longer than caps alone.

fan12.jpg


Now, making sure you know which side of the fan blows and which side gathers the air glue it to the flat side of the Ceiling Collar/Duct Starter assembly so that it will blow cool air into the duct and then into your terrarium.
fan7.jpg


Let it cure for 24 hours or so before it's ready to attach to a duct and use to cool your terrarium. It will still be stinky for a few days because Goop is a very smelly, and thick silicone type glue.
 
Now I just wanna know how you attached your humidifier to it!
 
The humidifier intersects the incoming air duct before it reaches the terrarium:

hl5.jpg


Just remove the directional flow cap out of the humidifiers output hole on the top of the tank. It's used to aim the fog where you want it in the room you won't need this. It pulls out for cleaning on most models I've seen. Then just stick a 1 1/2 - 2" diameter sump pump hose in the open hole (the hole is 2") and duct tape it in place. Then cut a hole in the 4" duct and stick the loose end of the sump hose in there and duct tape that in place. Turn the humidifier on and watch for any escaping fog vapors put more tape where there are leaks and then you're all set to hook up to a controller.

Note: I used to use clear tubing to go from the humidifier into the duct but it's rather expensive and algae actually grows in the clear tubes eventually blocking the airflow. The black sump hose should not have any algae grow in it and I got 25 feet of it for like $6. I only need 12" or so for this project.
 
That's interesting... thanks for posting! Having just done something like this myself, I had problems getting my fan to force all its air flow down the duct even though it was a 4" fan and a 4" duct. Do you feel like you get all 85 CFM out of the other side of your duct?

I just bought myself a duct fan - it's rated for 50dB. The Radioshack fan I have is rated at 36dB. Hmm. I hope it isn't too loud... that would be a real bummer. I might have to switch my fans for something more like yours...

And the 12VDC fan - I actually have that same Radioshack fan but the AC model that puts out 60CFM. Is there an advantage of DC over AC besides the apparent difference in air flow?
 
Any bends in the duct will reduce your flow by an exponential amount, the straighter the duct work the better for air flow. You wouldn't actually want 85 CFM blasting full bore into the terrarium as it would dissipate the humidity very rapidly, as long as there is a slight breeze keeping the air moving it's enough to keep it cool.

This is how I had the duct setup on my old 3 level succulent shelf (note no humidifier) using two 4" Ts and 1 90* elbow at the top to deliver airflow to each shelf.
airduct.jpg


I used to use the AC fan from Radio Shack but I like the DC ones now because of the switchable power supply which gives you more or less air flow and reduces the volume if the top setting is too loud. I sleep in the same room as my terrariums so I couldn't use the 4" diameter Inductor duct fan. I bought one and wired it up but it sounded like a rattling jet flying outside the window. I knew I couldn't sleep with that going 24/7. There may be a way to quietly mount them to something and if you don't sleep in the room it may not matter either if you can go out and shut the door. At the hydroponics shop they sell a fancy high power and quiet fan (at least how they have it mounted it's quiet) but they want over $100 for it and at the speed it runs it would likely eliminate the humidity I'm trying to build up in there.
 
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