Fan speed controllers.... The 'cheap' versus those 'transformer' types (variacs?)...

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NewGrower2011

Well-Known Member
So can anyone break it down for me - the difference between using one versus the other? I know some basic electronics/priciples...

From what I gather the cheap ones are essentially just a variable resistor basically... like one of the light dimmers from the local hardware store. Right? That would be a DIY for a fan speed controller unless there's more inside those little plastic boxes that I'm not accounting for... The down-side to using a variable 'resistor' is that you're still using the electricity and rather converting it to - guess what - HEAT... right? Just what you need in your grow room... more heat... And you're not doing yourself a favor on the energy bill either... doh...

Then there's the expensive - but "right way" - to control speed of a motor which is through use of a transformer stepping the voltage down as opposed to 'restricting' the flow... which these things I've seen going for big bucks (surprisingly big) and so far I think only "CanFan" makes one for the hydro market specifically (?)... so I thought either they're meant to handle much more amperage and run several fans using 1 controller as opposed to the cheap ones being for one and only one fan... OR... they're a giant "variable" transformer... which I think I've found the real terminology outside of the hydro/grow world is a "variac" - correct me if I'm mistaken... All that copper winding doesn't help the cost of these obviously...

If you know of good sources for these 'variable' ones that do it the "right way"... let me know... they weren't soley invented for our hobby so that means there's somewhere selling them without the inflated cost that comes with the association to a specialty/hobby market...
 
N

NewGrower2011

Well-Known Member
To be clearer... yes - I'm talking large AC fans... not those PC case fans which are DC based... god knows there's enough "fan speed controllers" offerings in the PC market...

Think the fan's you see on the hydro shops that are $100+ themselves... 400 cfm+ etc...
 
chis

chis

Active Member
i have a 27 dollar fan speed controller and it workd great but i had to fine tune it over a week and still check it daily if you can control the temperature coming in and mantain good growingtemps they work i check my babies every day so i adjust as necessary. The most expensive ones have times on them and you can have your fan come on at set times the cheaper ones just stay one at the percentage you set it at. you could get a titian controler and run every thing from that.
 
jondamon

jondamon

Well-Known Member
The differences are that the standard Controllers cut the power on and off to the fan to regulate the speed thus starting and stopping your fan continously to the desired speed you want.

A Variac speed controller regulates and reduces the amps/watts being delivered to your fan to control the speed. This way your fan is ON and the watts being delivered are less which causes your fan to run a slower speed.


The standard speed controller can make fans hum quite loudly and can reduce the fans working life.






J
 
E

everybodydoesit

Member
The following came from Growery.org. Seems to cover all the bases. Hope this helps.

[h=1]Fan Speed Control 101
[/h]Basic electrical methods for stealth fan oporation

[HR][/HR]

Fan Speed Control 101

I. Know your fan
In order to control fan speed, you have to know what type of motor your fan uses. Motors can be divided into two categories based on power source AC, and DC. AC fans are those you plug directly into a wall receptacle (Vortex, Dayton, Can-Fans), for more information about AC motors go to numeral II. DC motors are generally found in small fans like computer fans and rely on a DC power source like a rectifier (wall wart) or battery. For more information about DC fans, see numeral V.

AC fan:


DC fan:



II. Know More About Your Fan
AC fans use many types of motors but three types are important to us cabinet-bedroom size growers, shaded pole induction motors, permanent-split capacitor (PSC) motors, and AC-DC Universal motors (Brushed Motors). For a list of motor type based on manufacturers, see numeral III. Shaded pole induction motors are simple single phase motors known for low starting torque and long duty cycles. PSC motors are also single phase motors but unlike shaded pole motors, PSC motors use a capacitor to help them start. AC-DC Universal motors are general purpose motors found in many household appliances like power drills and vacuum cleaners; their short service life makes them an unattractive option for fans. There are other types of AC motor that have been used for ventilation purposes, but aside from shaded pole, PSC, brushed motors, and three phase motors (which are beyond the scope of this course), ac motors are unable to be speed controlled without serious modification and/or risk.
There are primarily two ways to control the speed of these motors, voltage control and frequency control; see numeral IV for more information.

III. Fan Manufacturer List
This information is relevant as of march 2009 but always be sure to double check by contacting your retailer or fan manufacturer! Using the wrong type of control with your equipment puts the fan and your controller at risk. This section is always in need of additions and corrections so if you have anything to add, post it or send me a P.M. and I'll be sure to include it.

Permanent-Split Capacitor
-Dayton squirrel cage blowers (Generally PSC motors, but they also make a shaded pole version)
-S&P Mix-Vent TD line
-Grainger squirrel cage fans

Shaded Pole Motor
-Vortex
-Can-Fan
-Valueline
-Elicent
-Active Air

IV. AC Speed Control Methods

Voltage
-Rheostat (Old dimmer switches): Poor choice, excess power converted to heat.


-Triac (New dimmer switches): Poor choice, inherent problems with triac controls risk fan lifespan.


-Triac w/ Snubber circuit (Fan speed controllers, Solid state controllers): Good choice, snubber circuit removes most of the risk to the fan. Still not the best because it can cause some motors to hum.


-Capacitance level control (No hum fan speed controllers, 3 speed controllers): Good choice, only limited by the discrete speed choices, no infinite control.


-Variable autotransformer (Variac): Better choice, continuous sine wave of a lower voltage (unlike a triac which chops up the sine wave to acheive a decreased voltage) allows fan operation with no hum.



Frequency
-Varable Frequency Drives (VFD, AFD): Best choice, complex circuitry senses changes in the motor allowing it to vary frequency of the AC source as well as the voltage which maintains a constant torque, unlike voltage regulation.


V. DC Speed Control Methods
DC speed control is much simpler than AC speed control. In order to lower the speed of a DC motor we must lower the voltage, this is accomplished in various ways. Linear voltage regulation relies on resistors, and diodes to remove the excess voltage as heat. Pulse Width Modulation sends bursts of energy to the fan and the averaging effect results in a lower net voltage and reduced energy use.


 
FootClan

FootClan

Well-Known Member
Yes ive been saying the same thing for 2 years now.......Even people at hydro stores dont understand that you are still using the same amout of PG&e when you slow the fan down and the extra power is disapated off..... Ive been telling people this for long time now and i still see people telling other people that if you turn down the fan you use less energy finilly somone on here talking about how it DOSENT reduce power cost and creates more heat.... Plus rep for you sir!!
 
M

Mr.Therapy Man 2

Active Member
Speedster controls will burn your house down,buy one that cost a little more cash,its worth the piece of mind,my speedster just would not kick on some mornings so when I smelled shit getting hot I knew my fans did not kick on,I got rid of those in about 3 days and that was 3 days late in my book,theres nothing worth burning your household memories and belongings for life.over 50 dollars..
 
N

NewGrower2011

Well-Known Member
So can anyone make actual product reccomendations? Let's start with the not so obvious and skip the $30 speedster nonsense.... what real products can we source? I'm thinking the industrial sector should
offer something with the "hydro" association driving up costs like I mentioned... Hell even if the markup isn't toooo bad - where can I find something I can order.... soon... ;-)

I'll take a few of those terms from that Growery post and see what I can dig up...
 
Hotwired

Hotwired

Well-Known Member
lol good thread

I use my old speedsters as on/off switches. Better than pulling the cord out every time I need to turn it off.

Hopefully someone is using a decent variac to recommend to us.
 
PlantManBee

PlantManBee

Well-Known Member
Wow! I've been looking for this! Thanks for the link because the can-fan brand is like $200 bucks locally. The hydro shop guy just looked at me like I was crazy when I brought up the heat generated by the speedster type. I'm going top spend the extra cash.
 
ASMALLVOICE

ASMALLVOICE

Well-Known Member
Greetings All,

I just received my speed controller for my extraction fans. It is a single phase vfd with onboard loop and/or remote input control. I got this on clearance at Graingers. $240(open box but unused), regular price $475. I can configure it to go 120 or 240 ( internal jumpers ) and has 12 amp capacity. This will allow me to dial in on the exact flow needed to maintain an ever so slight negative pressure or do rapid air exchanges ( scrubbing ). They have a ton of them, that are between 3-500 bucks, and will easily accomodate up to a 12 amp fan, be it 10" or maybe 12".

P1010121.jpg

P1010124.jpgP1010123.jpg
If fine tuning air flow with as little motor hum as possible, these are the medicine for that pain. These are far superior to any "resistive" manual controller.

Peace

Asmallvoice
 
N

NewGrower2011

Well-Known Member
Glad you found those... I've still not made a purchase here, but I did see Grainger has a lot of gear that might be useful (i.e. cycle timers)... I need to dig around their site a bit more...
 
B

berkman858

Well-Known Member
NewGrower2011 said:
So can anyone break it down for me - the difference between using one versus the other? I know some basic electronics/priciples...

From what I gather the cheap ones are essentially just a variable resistor basically... like one of the light dimmers from the local hardware store. Right? That would be a DIY for a fan speed controller unless there's more inside those little plastic boxes that I'm not accounting for... The down-side to using a variable 'resistor' is that you're still using the electricity and rather converting it to - guess what - HEAT... right? Just what you need in your grow room... more heat... And you're not doing yourself a favor on the energy bill either... doh...

Then there's the expensive - but "right way" - to control speed of a motor which is through use of a transformer stepping the voltage down as opposed to 'restricting' the flow... which these things I've seen going for big bucks (surprisingly big) and so far I think only "CanFan" makes one for the hydro market specifically (?)... so I thought either they're meant to handle much more amperage and run several fans using 1 controller as opposed to the cheap ones being for one and only one fan... OR... they're a giant "variable" transformer... which I think I've found the real terminology outside of the hydro/grow world is a "variac" - correct me if I'm mistaken... All that copper winding doesn't help the cost of these obviously...

If you know of good sources for these 'variable' ones that do it the "right way"... let me know... they weren't soley invented for our hobby so that means there's somewhere selling them without the inflated cost that comes with the association to a specialty/hobby market...
Click to expand...
I have (5) 6" Max-Fans and they come with built in speed controllers. Just thought I would throw that option out there.

P.S. - no hum at any speed.
 
Tripped circuits

Tripped circuits

Well-Known Member
if you run your fan with the controller that slows it down you are wasting electricity. Fans are made to run at an efficient speed. You would be better with a full on switched to a full off. Simple for two reasons, less wear and tear on the fan windings/bearings/stator and magnets. secondly if you run something more efficiently it costs less to run per work performed. just my little tid bit
 
acellular

acellular

Member
So it seems like the variac is the best for fans. There's a 5 amp on ebay for $65 delivered. So what can i use my Speedster on effectively? Does it work good on ecoplus water pumps? I'm gonna swap out my Speedster for the variac because my fans do hum pretty bad when dimmed down. I just want to know what will my Speedster work good on, anything?
 
jijiandfarmgang

jijiandfarmgang

Well-Known Member
acellular said:
So it seems like the variac is the best for fans. There's a 5 amp on ebay for $65 delivered. So what can i use my Speedster on effectively? Does it work good on ecoplus water pumps? I'm gonna swap out my Speedster for the variac because my fans do hum pretty bad when dimmed down. I just want to know what will my Speedster work good on, anything?
Click to expand...
You can use it on what it was designed to be used on "For use with brush type motors only."
 
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