Ceiling Fan Speed Control on Cheap Duct Fan = Extra CFM?

Hello all,
My grow tent has been a bit too cold lately. I'm drawing in cold air with a duct fan from a vent outdoors to cool the tent. This method has worked great for me to keep the tent cool for the majority of the year, but I have a slight problem. When I have this duct fan on, it's too cold. When I have this duct fan off, it's too hot.

It is just a cheap suncourt 160 CFM duct fan from home depot (a nice combo of like 3 of these in different sizes works really well to keep my small tent cool without having to get expensive overpowered fans). So of course the simple solution here was to just get a speed controller attached to the thing so that I can find a happy medium that supplies the right temperature. So I took a trip to the hardware store and all I could find were ceiling fan speed controllers (that you would normally install in your wall). I figured it wouldn't work, but it was 10 bucks so I decided to try it anyways, what the hell.

I hooked it up and tried it out and a very strange thing happened...
There are 3 different settings on this low, medium, and high. ... <--"high".
So the low and high settings don't seem to change a thing with the fan, it seems to blow at the same speed. But the medium setting, oddly enough, actually boosted the fan speed and I mean ALOT. Now I don't have an air velocity meter (who does?), but I'm pretty sure that the CFM of this cheap $30, 6" home depot duct fan damned near doubled.

And now I'm sitting here thinking I just stumbled upon this ingenious invention where I hacked this cheap 30 buck duct fan into something with the power of a much more expensive duct fan for $10.

Although my only thought is that maybe I am screwing with a resistor or wiring or whatever in the fan (I am NOT an electrician lol) and that this will only really work for some time before the fan breaks on me and burns out or something. So does anybody here have electrical know-how or stumbled upon this same thing with their duct fans before as well? Does it work to keep them running while "super-charged" like this? Or am I just gonna break my fan after a while?

This is kind of a strange question... so thanks for ANY help. I might just put this on my outtake vent and do a passive intake instead, if it does work...

Discontinue speed control and buy proper rated equipment for the fan ratings.

Possibly if you have some closed duct holes, windows or openings on your tent this will allow you to open them more reducing air speed through your tent a little thus raising temps. Works for me sometimes but may be worth a shot till you get the right gear.

It's so much more risk than is worth to push cheap shit above it's limit even if you know what you are doing. A lot of crap that is shipped in from you know where can barely operate at it's intended work load as is. Pay the price and get items that are tested and reviewed/deemed safe for the exact use imo. Or, be that guy who sets his tent/house on fire to remind the rest why they payed extra ;p.

Flowki said:

It's so much more risk than is worth to push cheap shit above it's limit even if you know what you are doing. A lot of crap that is shipped in from you know where can barely operate at it's intended work load as is. Pay the price and get items that are tested and reviewed/deemed safe for the exact use imo. Or, be that guy who sets his tent/house on fire to remind the rest why they payed extra ;p.

Click to expand...

Fuck that, be that guy as i havent seen a good tent fire for a while

A variable transformer works better. It adjust voltage. Its quieter and safer.

The cheap controllers clip sine wave and starts and stops the motor repeatedly.

Of course variacs are a little spendy but I would rather not burn my place down.

I use one similar to this.


I am also thinking that if two of the speeds don't work you have it wired up wrong.

LOL... I think I had found my answer after some deeper research just after posting. No worries, I am not running it. No fires. I know a variac will work but I mean the price is truly insane on those. Not worth it. I took the whole fan off and left it a passive intake. Seems to be working until a warmer day comes by and it gets just a bit too hot. But not too bad, I'll just keep putting off and on as needed. A pain, but whatever.