question on ventilation

[ConvexConepiece]

my 200mm centri is a bit of a screamer . You get used to it, and noise is a big issue for me and the person who lives right on the other wall to where im growing

[Roadblock]

The noise is relative to air speed and volume , its quite scientific if you get right into it , without going into it , a 250ml centr backed of in speed to the noise level of a 200 ml centri and the larger fan will move more air at the same noise level , the difference with Axials is they move air at less speed which makes them appear quieter for the same throat size and they are but they dont move near as much air for being the same size and they have very little torque so negative air pressure can pull them up a lot if you have not put some thought into your rooms natural flow inlet outlet sizes etc etc .

 

The most efficient setup is an over sized centri with a fan controller backed down to the noise you want , you can go from a screaming jet to you cant hear it ,, but right through the range it will push more air than the same size Axial at the same noise , and you have the potential to move a lot of air in a heat wave by just winding up the controller .

I have fan speed controllers on my inlet fan which is a 250 ml Fantech Centri ,, and temperature controllers on the outlet fans which is a 300 ml Axial the room also has a 200ml passive vent , between the two controllers you get it spot on all year .

 

300VA Fan Controller $32 from Bunnings .

The controllers are a piece of piss to wire up , just get a very short extension lead and cut the plugs of it and leave about 6 inches of cable from both plugs , strip the wires and rejoin the green and then the blue or black ( it will be one or the other ) back up , tape them two groups separately , now just run the active ( red or brown) wire through the controller , then tape it all up and plug the fan in the female of your controller and the other one into a power point and you away .

[grok]

great info roadblock....I been wondering on ways to cut down the noise of centrifugal fans...and i need to buy ones soon.

how noisy are your centi fans? can you hear them outside the room?

 

I also have read about fan silencers or mufflers for centrifugal fans, and carpet wrapped around the fan and making a baffle box to encompass the fan and stop sound escaping....so Im thinking acoustic ducting+baffle box with carpet+silencer+fan speed controller=a quiet centrifugal fan :yay:

 

does anyone know of centrifugal fans smaller than 100mm?

 

..and krazim yeah a 100mm centrifugal fan is what i would use...ive also been thinking of building a stealth cab with a 250watt HPS and the main concern i have had is whether a 100mm centrifugal fan can be made quiet enough to not be heard outside the room the stealth grow box is located.

[Roadblock]

great info roadblock....I been wondering on ways to cut down the noise of centrifugal fans...and i need to buy ones soon.

how noisy are your centi fans? can you hear them outside the room?

 

I also have read about fan silencers or mufflers for centrifugal fans, and carpet wrapped around the fan and making a baffle box to encompass the fan and stop sound escaping....so Im thinking acoustic ducting+baffle box with carpet+silencer+fan speed controller=a quiet centrifugal fan :yay:

 

does anyone know of centrifugal fans smaller than 100mm?

 

..and krazim yeah a 100mm centrifugal fan is what i would use...ive also been thinking of building a stealth cab with a 250watt HPS and the main concern i have had is whether a 100mm centrifugal fan can be made quiet enough to not be heard outside the room the stealth grow box is located.

 

The noise is relative to how much air you need to move , just remember no matter what moving a lot of air is noisy and there is not much you can do about it without going to a lot of trouble , depends how much you need to move against getting caught , the best way is to balance the books , its no good having heaps of lights additives heat bla bla if your airflow cant feed it , every room should be built from airflow upwards , Ive seen a lot of rooms that would be much more productive by backing off lights and heat instead of putting so much demand on the plants which works backwards giving you less yield , an efficient room is the aim by maximizing your resources all in balance , the most for the least thats my priority .

 

With my 250 centri , I have it inside the room in the corner enclosed in a 3ft square formply box packed with pink bats insulation , its motor is very quite inside the room , then I have acoustic ducting coming out of each end of the box , like the robots arms in lost in space , the inlet air long end goes outside and is pointing down with a shade cloth bag over it to baffle some noise and keep bugs out although not to many bugs survive a trip through a centri , it is in a hidden place outside the building , you can still hear it if your within 3or4 meters but it could be mistaken for other noises of in the distance and thats ok for my situation .

 

With acoustic ducting dont get it from a hydro shop they will rob you for it ,,, go to a air condition company and buy from them they use it all the time , cost me about $40 for 6mtrs for 300 ml and just put the fan down inside it as far as you need poke a hole to thread the fan lead out and then run duct tape around the outside of the ducting at the centre of the fan pulling it down tight against the fan , cut the ends off the duct to the length you want and drop the fan in a box can be cardboard and fill with insulation or rockwool with the duct sticking out , job done .

Edited May 28, 2008 by Roadblock