Hi All

Want to know why people are fitting these to their outtakes ?

I understand they give you variable speed, but most fans have 2 speeds anyway.

Surely if its for temp control just wire the fan to a room thermostat and wire it to the high/low fan speeds ?

So when temp high - fan high, temp low - fan low.

What are the benefits.

Cheers

Yeah I know someone who uses one well I think it's the one ur on about.small plastic White fan I think it cost him 20 odd quid looks a flimsey week little thing.

most fans only have one speed

Mine has 2 inputs, low, high.

If i fit a thermostat to it where is the best postion to place it in my 120x120 tent with 600w hps.

Ta

above the shade, or close to your exhaust, you want good air movement across it and out of direct view of the lamp, as you only want to be measuring air temp, if light is shining onto the stat it will be heated by the light converting to heat on contact and will be receiving a false reading, same with your thermometer

using a variac to lower ur fan speed = no fan buzz

Cheers guys. Not sure if mine makes a buzzing noise yet and i presume if it does it will be on high speed, if so i will fit a variac.

Cheers

For some people the fan might be too powerful and/or too noisy, and it is always nice to have some control to regulate the temps, etc.

your two speed fan aint a prima klima by chance is it?

coupla threads on here saying you shouldnt use a fan controller with them, the science i know not

I've never understood the use of these things. Given that Environment is the single most important factor in the grow (pretty much), and given you can never have too much fresh air exchange ..... a variac is like a hole in the head.
I know folks like 'em and use 'em. But honestly, I've yet to see anyone give me a really convincing reason to go forth and purchase such a device.

If cold temps and fan noise are not an issue then variacs are not nessesary but for people growing in cold garages or in small spaces a reduction in fan speed can help. I only have one grow space so when i harvest i can have the exhaust very low for a slower dry. I suppose the most important thing is you have enough fresh air, having more is great so long as it doesnt have a negative affect on security or temps.

Erbivore9 - Yeah, that's the usual reason. But sacrificing fesh air for temperature control reasons has always seemed to me to be a rather false econom; I'd rather fit heaters than reduce air intake.
I was kind of wondering if there was another good reason for these things. Im sure there must be, but it escapes me, for sure

Yeah it's the noise, even with acoustic ducting and carbon filters on both ends a 6" fan is pretty noisy. There's no way I'd be able to grow without one. Well I could but my neighbours wouldn't be too happy. A 6" fan on a dimmer can be a lot quieter than a 5" fan on full blast.

The reason people go for these instead of just a dimmer switch is that standard dimmers make the fan motor buzz so they're even louder. The Wac1 controllers are good too but have less control over exactly how loud they are.

I think they can be an advantage if you run an oversized fan, when its warm you can run it flat out but when its colder you can turn it down to the level of the smaller fan you would have bought and save yourself a larger heating bill. It is of course important that you dont run your fan slow enough to cause problems but i see it as a way of being able to use a big fan all year round, the advantage being gained in the summer when you can crank it up.

as has been said, an oversized fan running at half speed flows just as much air as a smaller fan on full speed, with half the noise. also, the airflow needed to replace the air in our rooms 3 times a minute, is a tiny fraction of the airflow required to control temps of an HID light. go and see for yourself, see what airflow the growroom calculator says you need based on your growrooms SIZE, then have a look at what size fan you ACTUALLY need to keep the temps under control, as long as you don't slow you fan too much then a speed controller is perfectly fine for controlling temps, but more importantly for most, keeping the noise down. plus it cost a SHIT load more in electric to bring the heat of your room UP than it does to simply (edit)(edit) slow the fan , you could easily quadruple the cost of your electric this way!!

I run an 8" high power ruck extract with a fan controller, keep it at 50% which is loads of air exchange, as soon as the temps creep anywhere near 28c (which is only on very sunny days) the fan kicks in full power and cools it straight down, a matter of a couple of minutes.

Very quiet 95% of the time and my temps stay spot on, one less thing to think about searching for a good enviroment.

Moving over to a full variac and thermostat as soon as Maplins get their fingers out to eliminate the very small buzz I have at the moment.


Woody

At lights off or cooler times its often unecessary to have maximum airflow. When i have lights off my fan is right down to slowest and that is easily enough airflow.

A fan on a controller buzzes like a bastard, a variac stops the buzzing by adjusting the voltage rather than the Pulse Width which is what causes the buzzing..

'can never have too much fresh air exchange' ......true but why use more than necessary ?

Hope that helps, doubt you will consider an answer from myself much use though



peace

edit for spelling

When your lights are off do you manually turn down your fans or do you have something that will do this automatically? I am a little confused as to what idling speed to leave my fans at.

if your turning your variac down manually, dont go below 40% power,
apparently this is the minimum you need to keep the fan internals cool.

& if you want to automate things, you can add a relay & a thermostat,
you set the thermostat to say 28F & if the temps go above that then
the thermostat kicks in & you get full power on the variac until the temps
drop below 28F & the variac goes back to the lower setting. sorted

Because a 10" fan running flat out sounds like you have a highly strung harrier jumpjet in the room trying to escape.

I prefer to run a 10" fan at 50% capacity than a 5" fan flat out, the sound is much much lower. So air exchange does not suffer it's just more stealthy and I also have the option of running the fan flat out in emergencies, mind you when it's going full tilt I'd be scared of it sucking the cat in.

which variac controllers do use recommend

Pretty much any 230V Variac is suitable for use with RVKs/Rucks.

And round and round we go

VARIAC INFO HERE

oh dear oh dear, even more money to spend i tell ya its an expensive hobby , why on earth don't the fans have variable control built in, its a riite money racket

Most of a growers expenditure is related to the growing environment, whether that be what the roots are taking in, lumens, box/tent, or air exchange.

There is most definitely an optimum environment in which our darlings will achieve their best.

Attempting to create and improve on that enviro and monitoring it is an endless pursuit.

I've decided to worry about it less. I'm confident I have the basics right.

I've had to say, "Enough!, I've let nature take its course and it's looking ok.

We are growing a weed and attempting to optimise its genetic desire to pump out a plump virgin flower that will never meet a boy.

It shouldn't be that hard, sometimes I think we get overly anal about the process.

God knows I'm guilty of this.

6 ml or 6.25 ml????????? hahahaha. Its a fine folly.

Most of us being boyz doesn't help, equipment mania can be devasting.

I used to be obsessed about climate control, until I realised that the extra leccy could be used to run an extra grow light instead.

Hehe thats my outlook on it all!,
it is nice to have nice things and boys dooo love their toy's, but at the end of the day it's night no at the end of the day it is a weed and before i learn't about all these amazing things that you can get to grow, i just watched the p.h. the temps, and the npk balance for veg or flower, and they grew very well, but for the persuit of them growing perfectly i want more toys!!!