Re: Re: Canopy fan suggestions..?
Re: Re: Canopy fan suggestions..?
<a href=showthread.php?s=&postid=13132131#post13132131 target=_blank>Originally posted</a> by aprosody
Why can't you put a pot. on an AC fan? Thats what a dimmer switch is for a light or a ceiling fan.....
FYI, if you are using a dimmer switch on a ceiling fan, you might need to replace your ceiling fan shortly
Not only that, but they make the motor give off a pretty annoying sound.
For variable speed fans (case and ceiling) there are switches that will set them to each speed. I have a 3 position switch for my ceiling fans that
looks like a dimmer switch, but it's actually a switch that's designed for variable speed ceiling fans.
<a href=showthread.php?s=&postid=13132397#post13132397 target=_blank>Originally posted</a> by AZDesertRat
cardiffgiant, adding fans to exhaust is a waste of energy if you already have fans blowing cool dry air in. All the additional fans do, if you have an enclosed canopy is move the exact same CFM that is fed to them. If your back is open thats a different story though. My canopy is completely sealed so I have one 4" Vantec in each end blowing in with holes drilled directly on top over the reflectors that have a greater surface area than the fans so they do not have to push against any head pressure. This also works well even when the fans are not running since it takes advantage of natural convection. You can stick your hand over the canopy and feel a natural draft with no fans.
I'd have a hard time disagreeing with you ,simply on the merit that you've built a canopy that functions the way that you want it to, and I haven't yet. However, I have had a lot of experience building computers and modding cases for airflow (totally different "hot enclosure", I know).
In theory... and it's generally theoretical, since the friction caused by obstacles and fan positioning impacts the performance of each fan (much like friction in our plumbing impacts water flow)...
My plan is to "seal" the back. Meaning, generally close it off, but it won't be air tight.
Intake Only - having only intake fans will create positive pressure within the airspace of the canopy. The general advantage of this arrangement is that the positive pressure in the canopy is created with cooler air. The negative is that this creates back pressure on your intake fans as they need to force the air out of the exhaust (assisted by the fact that heat rises). You also have two fans pointing at each other, which (much like powerheads) creates disturbance, but doesn’t dictate a flow.
Exhaust Only - having only exhaust fans will create negative pressure within the canopy. This could be an advantage when using very strong fans and exhausting very high heat. The negative is that this generally results in cooler outside air coming into the target area at a slower pace, and forward pressure is created for the fans as they work to pull cool air through the area.
Intake and Exhaust - an even flow situation in which (under appropriate conditions) the fans are feeding cool air in and exhausting hot air out at an even pace, resulting in optimal performance and maximum air flow for each set of fans. The drawback is that it's the highest cost configuration, and could be over kill.
One could use this option with one intake on one side, and one exhaust on the other. However, this will result in half of your bulbs getting cold air passed across them, and the other half getting hot air. Hot air will also rise to the top of the canopy, so you may end up sucking out cooler air, and trapping hotter air?
Overall - When I've cooled computer cases, even flow and positive flow configurations have always resulted in lower temperatures than negative flow. That being said, an even flow has been better than positive flow when the case is “sealed,†but positive flow has been better than even flow if the case is open (leaving the side off in hot months). In other words, just blowing cooler air in and letting everything blow out the side produces the best result, but might not be feasible for everyone.
Of course, all bets are off when the ambient temp of the room is the same or greater a temp than the canopy. In colder months, where you are heating the tank, you still want to cool your canopy to keep your bulbs cool. My plan is to put the exhaust fans on a 12v switch and turn them off when they aren’t needed.
It’d be interesting to do what I did with computer cases, and test temperatures with different types of configurations.
