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got a Variac..electrical question, need some advice

S

sicoltiva

Member
hello growers,

i just got a Variac to regulate the speed of my fan ( S&P 150 TD ).
It's this model : TDGC-0.5kM....see the photo too.
I am going to plug my fan to it which is now not running 24/7 and it is controlled by a timer.
SO putting the variac in between i'll have the timer controlling the Variac which controls the fan....
DO you think it will be an issue for the Variac life to be turned on / shutted off by the timer, so basically the on/off switch on the variac will be always on ON position ?
I'm not an electrical expert so i need some advice from you guys....

thankx a lot !
i'l post my impression once i'll set it up !

sicoltiva
 
S

sicoltiva

Member
photo...
 

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C

coconaut

Budweiser13 said:
Be careful with those.........
Click to expand...

Obviously......
</sarcasm>
Maybe you would like to explain why you should be careful.
I know they're heavy bastards, so you wouldn't want to drop it on your foot.
I've also heard something about another ICmagger almost getting zapped from one, but that doesn't mean Variacs in general are dangerous, just that one that gave a zapping was probably faulty.
 
KnuckleHedd

KnuckleHedd

Member
I use a Variac like yours to work on guitar or stereo amplifiers. For my Exhaust fan I made a speed controller for 20 dollars, or so. I've seen them already made up on Ebay for 25-30 dollars. With all due respect, using a variac to control a fan is overkill.
 
C

coconaut

There is a lot of debate over variacs and triacs regarding which is proper to use with inline fans.
I think a variac is truely what's best for an inline fan, but it's obvious that people get away with using triacs. I would bet that most people who have a fan die prematurely can attribute it to a triac.
 
foaf

foaf

Well-known member
Veteran
I have a digital one that works fine on the big inline blowers, but for some reason... I had 4 small in 4" inline duct fans that were circulating the air around the space, and the "fan dimmer" somehow "burned" all 4 of them out. they were cheap and I dont understand it, but it happened for sure fwiw. the specs on mine says "* Can drive single phase 120 Vac induction motor type fans up to 750 Watts." so appearently my small fans weren't this type. they have a little transformer on them and the motor is called "110V, Class B, Thermally Protected (T.P.)".
 
S

sicoltiva

Member
KnuckleHedd said:
I use a Variac like yours to work on guitar or stereo amplifiers. For my Exhaust fan I made a speed controller for 20 dollars, or so. I've seen them already made up on Ebay for 25-30 dollars. With all due respect, using a variac to control a fan is overkill.
Click to expand...

i understand, that's why initially i got a triac speed controller.
Wired it directly to the fan wires. it's small,, light and pretty sensitive. The problem is that is i move the speed down too much ( ...and it's not that much, about 15 % of the rotation on the knob ) the fan start to hum and make a mechanical noise due to low speed.
I read a lot of info on the forum ( incredible resource ! ) and fuond out that variacs was a good choice ( for S&P inline fans..)
Bought one , plugged it and works great. no hummming on the fan , total control on the speed.
It's about double the price of the first sped controller i bought ( about 15 $$ against 50 $ of the variacs ) but i'm very satisfied with the control it is giving. and i 'm not able to make a DYI controller....:whistling:
I also read about pontiac getting a shock from it...when i plugged mine i made sure i had a good rubber soled shoes and rubber gloves too..you know , just in case.
All was smooth so i think that pontiac just got one with factory problems...

sicoltiva
 
KnuckleHedd

KnuckleHedd

Member
This is the first I've head of triacs causing a motor failure. Mines been hooked up since 2004...maybe I just got lucky,eh. I use a 10" Fantech XL plugged into the speed control, which is plugged into the room controller. I'll make a note of the Variac option for future reference.
 
G

good drown

i thought pontiac took it apart, and it shocked him. it was unplugged from the wall, but the unit has a transformer in it, so it held power. it was a cheap made in china one. thats only if memory serves me correct.

most inline fans i have seen will hum if you use a traic controller at less than 80% power. variacs are great for dropping your HUGE fan down to 30% for a great stealth mode
 
S

sicoltiva

Member
good drown said:
i thought pontiac took it apart, and it shocked him. it was unplugged from the wall, but the unit has a transformer in it, so it held power. it was a cheap made in china one. thats only if memory serves me correct.

most inline fans i have seen will hum if you use a traic controller at less than 80% power. variacs are great for dropping your HUGE fan down to 30% for a great stealth mode
Click to expand...

yes that's what i see doing to my S&P fan , which is already pretty silent itself...
yes, maybe pontiac took it apart dont' remember either. that could have been a reason.
The made in china thing ..i don't know . We are surrounded by made in china electrical products and it doesn't seem to be an issue everytime. Aslo chinese factories can manufacture good products too.
If products are sold in the us or Eu usually they should pass quality control test etc so they should be safe.
i hope.
 
C

choch

Member
If you ever listen to a fan on a variac and then run the same fan on a triac you will have no question in your mind about which is better for the fan motor, and which is better for the grower who needs to keep sound to a minimum.

The triac does something funny to reduce the power rather than just give a steady feed of lower voltage at the correct cycle rate as the variac supplies. With the triac the fan is not getting the power continuously and the cycle rate is somehow affected as well. It results in the fan motor constantly being in that startup state like when you first plug it in.

While you reduce the air movement and related noise you create new motor noise - which I have a hard time believing is a good sign. Even on a small circulation fan the triac will create noticable motor noise.

You can dial an 8" elicient down to 45 or 50 volts on a variac and still have tons of negative air pressure in a dr120 with two passive 6" intakes, and it is sooo quiet. A small circulation fan on low drowns out all sound of the exhaust. With a quieter fan like the s&p it would be amazing.

Man the stress I could have avoided if I'd known about variacs years ago.
 
S

sicoltiva

Member
Budweiser13 said:
Here you go page 5 read imnotcrazies post. Use a variac if you want also this site has a nice search engine....:biggrin::smokeit:http://www.icmag.com/ic/showthread.php?t=112531&page=5
Click to expand...

These are the the one i bought when i got the S&P 150 TD fan.
I actually called the company before buying it and they said it was working with the fan.
The problem is that turn the speed down and the motor makes noise.no way to change it.
I went throught the several post about this topic included imnot crazy posts, which are very detailed.
He is actually stating that variac can work safely on S&P TD series ( i guess all models..100 150 etc ) due to their motor design.
The quantity of air movement is another discussion i think...
I can say that i'm satisfied with the performances of the fan i bought both in terms of noise level and air movement. i also have a small tent so the need of someone with bigger set ups will be different and they may need more air movement.

The point of my initial concern about buying a variac for my fan. Other grower posted good and safe experiences using it on a S&P fan.
I'm not an electrical expert but i found imnot crazy post very interesting to understand that if i had another type of fan ( ie. centrifugal --more air movement etc ) a variac wouldn't have been a good choice...
The fan is not running on a varica and it SUPER silent turning the speed down at about 90 volts..

Trust me i wouldn't bought a variac if the speed controller i got for 15 $ wasn't causing weird noises in side the fan.


sicoltiva
 
Batboy

Batboy

Member
Sicoltiva - I am very interested in your experiences. I currently have a TD-150 with a $25 triarc controller. If I keep the fan at or near full power (on both the high and low settings on the fan), all is fine and all I hear is the noise of the rushing air. The problem is when I try to turn the fan down further, I hear the mechanical hum of the motor over the noise of the air.

My problem is that my cab is in a cold room and when the fan is too strong, it will drop the inside temp too much. I can't currently turn the fan down to where I want to because of the motor noise.

Can you tell me with any certainty if that hum will disappear with the Variac? My ideal speed is with the fan on the low setting and the speed controller at or below 50%. Where did you buy yours? Any special wiring required? Does it get hot? Thanks
 
S

sicoltiva

Member
Batboy said:
Sicoltiva - I am very interested in your experiences. I currently have a TD-150 with a $25 triarc controller. If I keep the fan at or near full power (on both the high and low settings on the fan), all is fine and all I hear is the noise of the rushing air. The problem is when I try to turn the fan down further, I hear the mechanical hum of the motor over the noise of the air.

My problem is that my cab is in a cold room and when the fan is too strong, it will drop the inside temp too much. I can't currently turn the fan down to where I want to because of the motor noise.

Can you tell me with any certainty if that hum will disappear with the Variac? My ideal speed is with the fan on the low setting and the speed controller at or below 50%. Where did you buy yours? Any special wiring required? Does it get hot? Thanks
Click to expand...

hi batboy...i dont' hear any hum using the variac. I set it down between 60 and 70 volts and it works very smooth.
NOthing compared to the mechanical noise of the triac controller i have ( about same price as yours ...).
I've tried at lower voltage -below 50 volts - and you hear a little bit the fan motor spinning but to be honest very very minimal which you can always muffle with a box around it. for me that's too low because temps goes up cooling a 400W
I sleep in the same room and that was one of my main point to get a more silent operation at night. I'm very satisfied with the control that i have with the variac.
I put it on a shelf over the tent and honestly i haven't touched the body of it yet after several hours of operation. SO idon't know how hot it gets...i 'll take a look.
I remember reading in the forum of a user who talked to a S&P technician who was telling him that they use variacs to test S&P fan in continuos operation.
I have my fan wired at low setting, i leave it at full speed during the day and turn it down at night. Also works well for stealth purposes which is a concern i have too in my set up.
No wiring required, just plug the fan to the varic and turn..if you read few post back there is someone saying that has the variac controlled by a timer ( same as me ) so always in the "on" position..turned on and off by the timer automatically.
I got it from this website : http://webtronics.stores.yahoo.net/ensavat.html
hope this helps

sicoltiva
 
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