Is DC current fan better than AC current fan (for odor control)?

raggyb

raggyb

Well-Known Member
Would you disagree or agree? What are advantages of DC? I want to consider a DC powered fan instead of AC. This is pertaining to a 6" round duct with odor control filter attached.

Summarizing the link https://www.pelonistechnologies.com/blog/advantages-and-disadvantages-of-ac-fans-and-dc-fans , summary in purple, but what do you think?

  • In the past, big AC fans were typically less expensive compared to big DC fans. Today however, their price difference is negligible due to their payback advantage.
  • Consumes less power DC fans are widely regarded as the most efficient type of fans. They consume significantly less power than AC fans. In fact, DC fans consume up to 70 percent less energy to produce the same output as traditional AC fan types.
  • PRO: Minimal electromagnetic interference (Why computers use them)
  • PRO: Acoustically Quieter, DC fans make use of a new type (sin180) of electronically commutated motor (ECM). Not only are these motors ultra-efficient, they are also incredibly quiet. (I don't know about this because I saw one on you tube was a noisy little bitch)
  • PRO: Variable flow, With minimal additional cost, the DC fan can offer a variety of speed control functions, so that the fan can meet the airflow target of a given application. The fan can be controlled by:
  • Voltage
    • Current
    • Temperature
    • Resistance
    • PWM signals (is this hard to do?)
By controlling the fan speed according to what is needed, the life of the fan can be increased and its acoustical airflow noise can be kept to the minimum necessary.​
  • CON: May require an AC to DC converter, The AC fans are powered by an alternating voltage source. The DC fans are powered by a constant voltage source. This means that, the DC fan must have an AC to DC converter, either externally or included internally in the DC fan to convert AC to DC Voltage to power the DC fan.
 
Renfro

Renfro

Well-Known Member
I would be more concerned with CFM and ability of the fan to cope with static pressure. Concerning yourself with the current wars is really a moot point. When it comes to really moving air for a grow you really can't beat the AC induction motor for it's power.
 
J232

J232

Well-Known Member
DC has the advantage of brushless motors and efficiency, ones not better for moving air alone. Your just referring to what spins the blade.
 
Romeo7701

Romeo7701

Well-Known Member
AC/DC is irrelevant the CFM is what you need to focus on my friend I have a squirrel cage Dc fan that is 4''
3 speed and will move up to 130 CFM.
 
raggyb

raggyb

Well-Known Member
thanks for the replies. brings up some follow up questions if you know:

Renfro said:
I would be more concerned with CFM and ability of the fan to cope with static pressure. Concerning yourself with the current wars is really a moot point. When it comes to really moving air for a grow you really can't beat the AC induction motor for it's power.
Click to expand...
I was wondering about static pressure because you mentioned that in another post. I'm guessing the rated CFM's alone won't address the fan's ability to respond to static pressure. I guess some fans adjust themselves to changes in static pressure to maintain the cfm and some don't.

J232 said:
DC has the advantage of brushless motors and efficiency, ones not better for moving air alone. Your just referring to what spins the blade.
Click to expand...
Haha I'm misunderstanding this what you mean by 'ones not better for moving air alone'. Do you mean dc is not better than ac for moving the same amount of cfm per watt?

Romeo7701 said:
AC/DC is irrelevant the CFM is what you need to focus on my friend I have a squirrel cage Dc fan that is 4''
3 speed and will move up to 130 CFM.
Click to expand...
I think I would like the DC if PWM speed adjustment works better than with AC and if it works the same way on any DC fan. Also I had a variable box thing on an AC can fan power cord and it seemed it fucked up the fan. I didn't listen to the people writing that that happens and regret that. For some reason I guess more expensive AC fans don't get fucked up by choking back the current? Was it the induction motor you need to prevent that or something else?
 
Renfro

Renfro

Well-Known Member
raggyb said:
I was wondering about static pressure because you mentioned that in another post. I'm guessing the rated CFM's alone won't address the fan's ability to respond to static pressure. I guess some fans adjust themselves to changes in static pressure to maintain the cfm and some don't.
Click to expand...
It's mechanical at that point, some fan designs can cope well with static pressure, like centrifugal fans. Axial fans really don't do well against static pressure and a mixed flow fan is somewhere in between.
 
Renfro

Renfro

Well-Known Member
raggyb said:
I think I would like the DC if PWM speed adjustment works better than with AC and if it works the same way on any DC fan. Also I had a variable box thing on an AC can fan power cord and it seemed it fucked up the fan. I didn't listen to the people writing that that happens and regret that. For some reason I guess more expensive AC fans don't get fucked up by choking back the current? Was it the induction motor you need to prevent that or something else?
Click to expand...
An AC fan that is controlled by a variac will be by far the best solution. Many cheap solid state speed controllers will distort or chop up the sine wave causing motors to groan and/or even run hot.
 
Jesusgrowsmygrass

Jesusgrowsmygrass

Well-Known Member
I like EC fans a lot, they use half the power of AC fans and move the same amount of air. Look at Hyper Fans ( https://www.hyper-fans.com/shop/product/hyper-fan )and AC Infinity Cloudline ( https://www.acinfinity.com/duct-fan-systems/ ). These are speed adjustable inline fans, that have hookups for external speed controls that can be linked to temperature, humidity, time of day, etc if you are nerd enough to learn about PWM dimming. the Hyper Fan works on 0-5v PWM dimming and the AC Infinity works off of 0-10v PWM dimming. The AC Infinity is slightly quieter and a variac is not efficient.
 
raggyb

raggyb

Well-Known Member
Renfro said:
An AC fan that is controlled by a variac will be by far the best solution. Many cheap solid state speed controllers will distort or chop up the sine wave causing motors to groan and/or even run hot.
Click to expand...
I don't know what it was maybe not the variac but the variac didn't seem to work right on the ac can fan. So I don't think it was solid state with a turn knob. If the knob turns say 360 degrees it was only like the degrees between 60 to 90 that changed the speed from 0% to 100%. The response was wacky too and it was almost impossible to tune in the speed I wanted. And eventually the fan would only work without the variac and then still not very well. It takes like 5 mins to an hour after pluging it in for it to start blowing. I didn't check that device out with a multitester and if I did I don't know how I would tell what's wrong with it if anything. Maybe it's the ac fan that's incompatible with the variac which is what I thought i read people saying.
 
Renfro

Renfro

Well-Known Member
You have pics of this gear? I am puzzled by your description. Stick a meter on the variac output and measure the voltage as you turn the knob, see if it is working as it should.
 
raggyb

raggyb

Well-Known Member
Jesusgrowsmygrass said:
I like EC fans a lot, they use half the power of AC fans and move the same amount of air. Look at Hyper Fans ( https://www.hyper-fans.com/shop/product/hyper-fan )and AC Infinity Cloudline ( https://www.acinfinity.com/duct-fan-systems/ ). These are speed adjustable inline fans, that have hookups for external speed controls that can be linked to temperature, humidity, time of day, etc if you are nerd enough to learn about PWM dimming. the Hyper Fan works on 0-5v PWM dimming and the AC Infinity works off of 0-10v PWM dimming. The AC Infinity is slightly quieter and a variac is not efficient.
Click to expand...
Thanks. I'm pretty nerdy but on the 'bright' side don't use LEDs. i see that an EC is combo of AC and Dc. Add's another option to save power and has potential for PWM but i don't notice it's open to homemade controls.

I get it now how axial fans don't deal with static pressure as well as centrifugal. I don't know yet if DC or centrifugal DC speed can be rigged to adjust by homemade PWM controls. I looked up 4 fans

1) A Chinese DC centfug fan $60:
  • Flow 230 CFM
  • Voltage 12 DC
  • Amperage 2.1 amps
  • Static P curve not given
So that's 24W. Can be used with a carbon filter? I guess so, since it's centrifugal.

2) A stronger centrifugal:
  • Flow 552 CFM open flow
  • Flow 462 CFM at 0.2 inches static pressure
  • Flow 358 CFM at 0.5 inches static pressure
  • Voltage 12 DC
  • Amperage 9.4 amps full load
So 110W if full load

3) a Cloudline S6 (EC can fan) $110:
402 CFM, max power draw 64W
Didn't notice PWM control option.

4) a Cloudline Rax (AC 6" can):
265 CFM
warns cant handle high static pressure
37W, so not many more watts than 1) even though AC.
However, cannot be used with carbon filter, lol.
But manual speed control is built in.
 
raggyb

raggyb

Well-Known Member
Renfro said:
You have pics of this gear? I am puzzled by your description. Stick a meter on the variac output and measure the voltage as you turn the knob, see if it is working as it should.
Click to expand...
It's clipping. Looks like this. Like only a cm in the green is the actual span that makes a speed difference. So Off, low, med and high all fall within the green, lol.

1604177594600.png
 
raggyb

raggyb

Well-Known Member
Renfro said:
No, they are a very analog / mechanical device.
Click to expand...
I see that now on google. I guess even infinity is attaching the cheapo crap thing i have to theirs but you would think theirs would work better since it's their good name at stake.
 
lazaah

lazaah

Well-Known Member
raggyb said:
I see that now on google. I guess even infinity is attaching the cheapo crap thing i have to theirs but you would think theirs would work better since it's their good name at stake.
Click to expand...
Infinity are EC fans that use a DC motor and use a PWM signal to speed control (like controlling a servo with arduino)
 
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