Fans in the Hood
- Thread starter fishfood
- Start date
zeppelin
Member
The fans I have for the canopy I am building are encased in a plastic square with four holes in the corners for mounting. They are as thick as the fan. Kind of a box around the perimeter. Got mine from www.mcmelectronics.com Stop over there and look at their fans. Should give you an idea.
Larry
Larry
hairtrigger
Active Member
You can always go to home depot or lowes... they should have some plastic brackets you can use to extend the mounting reach. Also, when you put the fans on.... make sure one pushes air in... and the other sucks it out.
rsd
Member
I set up amp racks and dimmer racks for a living. Basically those racks are like a hood. They have gear inside that creates way too much heat and needs to be cooled by fans. We use panels cut with slits over an area the size of the fan, then we mount the fan directly to this vented area ( inside of the "hood"). We measure the flow of the air and found that if both fans push air into the unit that we can expect to see @ 90% of their rating actually be used. (i.e. 10 cubic feet per minute (cpm) x 2 fans = 20 cfm -rated-... in reality we get 17-18 cfm) When one fan pushes while one pulls air out we see the air doesn't always leave the unity but circles with in the unit. and we only see 1/2 or less of expected air movement.
To make a short story long... mount the fans inside the hood, maybe don't cut the hole the same size but lots of little holes.... also if you leave a 1/4 inch between the fan and the hood wall you can add an air filter to remove house dust and hair. I did and am very happy to see it work. Also 2 fans pushing air into the hood will force a better ACTUAL exchange than one pushing and one pulling.
It keeps our gear very cool this way... think about the air filter for sure.
To make a short story long... mount the fans inside the hood, maybe don't cut the hole the same size but lots of little holes.... also if you leave a 1/4 inch between the fan and the hood wall you can add an air filter to remove house dust and hair. I did and am very happy to see it work. Also 2 fans pushing air into the hood will force a better ACTUAL exchange than one pushing and one pulling.
It keeps our gear very cool this way... think about the air filter for sure.
zeppelin
Member
You can just cut the hole the size of the fan blades, say, a 3" circle. The box surrounding the fans is a little bigger, and SQUARE. The corners should have hood material behind them to screw into. Slotting the area is also a nice option as mentioned. BTW, the filter idea is a very good one, along with aiming both fans inward. Thats the way I've done it on the amp racks I've built in the past also. Great tips.
Larry
Larry
broomer5
Active Member
Interesting.
I mounted my fans in the top ceiling of the canopy - both mounted to force air out, with an inlet cut in the lower back of the canopy.
My thoughts were to prevent and convection within the enclosed area, and allowing cooler air to be sucked in the bottom, which in tur would pass over the lamps, and the heat exhausted out the top.
My goal was to reduce heat at the water surface, not necessarily cool the lamps.
The lamps burn hot no matter what you do with the air.
The water is what I wanted to take care of.
I mounted my fans in the top ceiling of the canopy - both mounted to force air out, with an inlet cut in the lower back of the canopy.
My thoughts were to prevent and convection within the enclosed area, and allowing cooler air to be sucked in the bottom, which in tur would pass over the lamps, and the heat exhausted out the top.
My goal was to reduce heat at the water surface, not necessarily cool the lamps.
The lamps burn hot no matter what you do with the air.
The water is what I wanted to take care of.
bobothewizard
Member
One fan on each end, set up to take cool air from one end, blow it across the water to the other fan and out.
bobothewizard
Member
Dam thats a huge picture, my apologies.
rsd
Member
Boomer:
I thought about that with the aquarium... but with mine I chose to compress the air with in and force the warm air out. I'm willing to bet that it you reversed your flow you would see a drop in water temp (except you probably have a heater) but you'd also see an increase in evap. When fans pull air from a confined space they create vortex's around the perimeter of the fan box... this air is "thinner" or less dense.... essentially the fan cavitates to some extent.... as if a PH was pushing water or water diffused with air. I wouldn't change your set up because you know it works and is already balanced. But if you had a heat wave and didn't want your chiller to work too hard you could try it out.
For everyone: Since air like water follows the path of least resistance.... immagine air comming into the canopy and heading directly for the fan(s) that is pulling out. Alot of dead areas for warm air to swil round and round getting warmer.
Now immagine a hood were fans push in. Fans compress air very easy. Immmagine air forced into the hood and forcing air out EVERY possible exit at almost the same rate it comes in at. Multiple exits = multiple paths. Some swirling but more like small tornados that roam around the area.
We actually map our air paths in some environments with smoke (not recommended for set up aquaria) Its kind of fun to see.
Anyways guys... what ever you have set up is working for you, don't change your balance nless you REALLY want. But is it's not working for you try an all push system and see if you like it.
Just my 2 cents.
"If it's a penny for your thoughts, and you give your 2 cents worth... hey somebody's making a penny!" Steven Wright.
I thought about that with the aquarium... but with mine I chose to compress the air with in and force the warm air out. I'm willing to bet that it you reversed your flow you would see a drop in water temp (except you probably have a heater) but you'd also see an increase in evap. When fans pull air from a confined space they create vortex's around the perimeter of the fan box... this air is "thinner" or less dense.... essentially the fan cavitates to some extent.... as if a PH was pushing water or water diffused with air. I wouldn't change your set up because you know it works and is already balanced. But if you had a heat wave and didn't want your chiller to work too hard you could try it out.
For everyone: Since air like water follows the path of least resistance.... immagine air comming into the canopy and heading directly for the fan(s) that is pulling out. Alot of dead areas for warm air to swil round and round getting warmer.
Now immagine a hood were fans push in. Fans compress air very easy. Immmagine air forced into the hood and forcing air out EVERY possible exit at almost the same rate it comes in at. Multiple exits = multiple paths. Some swirling but more like small tornados that roam around the area.
We actually map our air paths in some environments with smoke (not recommended for set up aquaria) Its kind of fun to see.
Anyways guys... what ever you have set up is working for you, don't change your balance nless you REALLY want. But is it's not working for you try an all push system and see if you like it.
Just my 2 cents.
"If it's a penny for your thoughts, and you give your 2 cents worth... hey somebody's making a penny!" Steven Wright.
hotjob4
New Member
I installed 2 fans in my canopy on my 110 reef tank. The easiest way to cut the holes was to use a 4" round hole saw that you put in your drill. That is the perfect size for the blades to move the air and leaves enough of a space to either bolt or screw the fan to the canopy. Be sure to use stainless screws or bolts to mount the fan due to rusting with the salt water. I put one fan on one end of the canopy and the other fan on the opposite end. One was an intake and the other was for exhaust. You do get some evaporation from the moving air but it lowers your water temp. I finally invested in a chiller.