How Do I Install a Duct Fan to Operate Most Efficiently?

[SmokeyMacPot]

Principles of effective ventilation
Many growers own fans powerful enough to move air of a city block in Manhattan, but has failed to install it properly, causing greater pressure reduction. This extra pressure drop is called the system effect or system dissipation, and can cause the fan to produce a smaller volume of air than indicated in the fan diagram.

The following factors must be considered in order to avoid system dissipation:

At the Inlet
* The distance to the nearest wall must be more than 0.75 the inlet's diameter.
* The inlet duct's cross section must not be greater than 112% or less than 92% of the fan inlet.
* The inlet duct's length must be at least 1 x the duct diameter.
* The inlet duct must no have any obstacles to the air flow (dampers, branching or similar).

At the outlet:
* The angle at the reduction of the duct cross-section must be less than 15 degrees
* The angle at the enlargement of the duct cross-section must be less than 7 degrees
* A straight length of at least 3x duct diameter is required after a duct fan.
* Avoid 90 degree bends (use 45 degree)
* Bends must be shaped so that they follow the air stream after the fan.

If the connections are different from this, there could be a greater pressure reduction.

Circular duct fans for example, are propulsive, pushing the air. And should be installed so that the long duct is after the fan itself.




Author: Rouhea

 

[E Doh907]

arent u supposed to pull the air out not push out with the circular vent fans?

 

[Flying Dragon]

I'm still collecting parts for my 5x5 tent grow, but I have my sealed air-cooled light hooked to a dedicated inline fan... and the fan (mounted outside the tent) is pulling air in through a short hose, through the light, through a long hose, then out the fan. Backwards? Do I really need to flip the fan around?

 

[Flying Dragon]

I flipped my fan around. Now air goes into the fan, into tent through duct into sealed air-cooled light, out of tent through duct. On when light is on. Pushing, not pulling. Thanks, Smokey!

 

[Budd64]

I am thinking I will stand a carbon filter in my 1.2 sqm tent, sit the fan on the filter, run duct through my cool tube the out of the tent. The fan will be pushing air. If I get a silencer as well, where do I place it? Should I stand it on the exhaust of the fan then run the air through the cool tube? I hope they aren't too long else I will be all the way up to the ceiling.?

I have searched the net to find out how much heat my 1000 watt HPS an MH will produce but it is complex. What sort of energy in heat form is produced by these lights? How often will I need to vent? I will use a cool tube, does this need the fan running constantly? My ballast will run the 1000 watt globes at 60-80-110%, so how hot is that? I bought a fan speed controller just in case! I will be experimenting with this set up but rough data could help. With this setup, if I need the fan on constantly, I guess I will need to fork out for a A/C for hot days. I will have a constant room temperature to work with then, but it's expensive. If two fans are an answer, one for humidity and heat in the tent and the one for to keep the cool tube at a reasonable temperature, what size fans should I get?

Would a condenser in the tent be all I need to pull out humidity, instead of changing all the air? Where do you buy small condensers ( dehumidifier)?

 

[iboxweed]

I have gull wing reflector which is a big mistake to get rid of heat in a closet grow. live and learn.Living in florida waiting for 24/7 airconditioning to begin to solve my problem.600 hps is nice but led may be the way of the future for closet growers.

 

[gwhiz]

Simple and nice. Good job!