Need help choosing a fan speed controller please.

[CottonTexas]

Sea Choice In-Line Bilge Blower PN: 41841 has a 76mm fan capable of moving 240cfm of air and requires a 5A fuse, but I do not know how many watts.  I would like to speed-control two of them, and I know absolutely nothing about pulse width modulators with the exception that I know you don't want to accidentally wire them backwards.  

My guess is that I would need to find a PWM capable of handling 10A, but again, I am pretty clueless.  The one above is good for up to 400W, but really I don't have any idea as to how many watts I'm going to need it to handle.  I know there's a wealth of knowledge here, so if someone with some experience wouldn't mind chiming in here, I'd be very grateful.  Many thanks in advance, Cotton

 

[highdesertranger]

well 10amps at 12 volts would be 120 watts. but I would go with the charging voltage so say 14.2v x 10a = 142 watts so that controller is well in the range. however I too know nothing about these controllers so some one with experience needs to chime in. highdesertranger

 

[SternWake]

Look for 21 khz frequency or higher. Or you will hear motors whine at reduced speeds

 

[SternWake]

An ebay listing of that blower says it draws 4.5 amps., so likely about 70 watts at battery charging voltages.

Overkill can be a good thing:

This one has a casing and can be set to 22KHz.

I have many LED PWM dimmers at 13KHZ, and they make my fan motors whine very annoyinglly. I'd rather hear the fan at highest speed than slowed down and whining

https://www.amazon.com/uniquegoods-...2&sr=1-45&keywords=pwm+motor+speed+controller

There are many options, I'd ust make sure it is for a DC motor, can do 100 watts or higher, and is 21Khz or higher.

 

[CottonTexas]

Thank you for the helpful replies. If I may, I've got one more question:  How would I go about integrating two 4" iVac electric blast gates?  The easy answer is to add a toggle switch, but I'm hoping to have them automatically open when I turn the fans on, though I'm pretty sure they wouldn't like the reduced power coming from the PWM.  Is there any way to tie the blast gates into the same switch?  Thanks again for the replies here.  Cheers, Cotton

 

[highdesertranger]

does the PMW have it's own on/off switch? or is it just a speed control and needs a separate switch? if it needs a separate switch then it would be easy, just tap out a wire after the switch and before the PMW. highdesertranger

 

[BradKW]

I've looked at those blast gates a few times, still might incorporate one. Two questions I never found certain answers on were: 1) will it operate on 12v dc? comes with a transformer, but didn't find specs for it. and 2) how much of a seal does the gate provide in closed position? I've built dust vac systems with normal gates, and they are pretty loose on tolerances, only really sealing when the vac sucks them tight to housing when in closed position.

I am thinking of using it as a bathroom shower vent, but it would be sharing the ventilation duct with the AC intake, and I don't want my AC sucking out interior air.

I have actually bought the fans and PWM controller. I went with two Noctua SSO2 @ 130 CFM each, controlled by a NZXT Sentry Mix 2 Fan Controller that can also control some extra fans for maybe electric cabinet ventilation. The fans are installed, but haven't gotten to the controller yet. Here's a thread about this, post #6, and iirc we got into detailed PWM discussions later in thread...   So I swallowed a bird to catch the spider...

 

[CottonTexas]

I've looked at those blast gates a few times, still might incorporate one. Two questions I never found certain answers on were: 1) will it operate on 12v dc? comes with a transformer, but didn't find specs for it. and 2) how much of a seal does the gate provide in closed position? I've built dust vac systems with normal gates, and they are pretty loose on tolerances, only really sealing when the vac sucks them tight to housing when in closed position.

I am thinking of using it as a bathroom shower vent, but it would be sharing the ventilation duct with the AC intake, and I don't want my AC sucking out interior air.

I have actually bought the fans and PWM controller. I went with two Noctua SSO2 @ 130 CFM each, controlled by a NZXT Sentry Mix 2 Fan Controller that can also control some extra fans for maybe electric cabinet ventilation. The fans are installed, but haven't gotten to the controller yet. Here's a thread about this, post #6, and iirc we got into detailed PWM discussions later in thread...   So I swallowed a bird to catch the spider...

You're right that the iVac blast gates are 12vAC (not DC).  I can't believe I missed that!  I'm glad you pointed that out, because I think you might have just saved me a coupla' hundred bucks!  I wouldn't trust them to be very tight anyway, but since I planned on using reusable "performance" automotive mushroom air filters, it wasn't as big of a deal for me.  My other option is to use automotive exhaust cutouts which I know will be a tighter seal, but present a new problem in how to control them automatically since they're normally on a momentary switch. :huh:  Your fan controller is sweet BTW, but Amazon says it's for 3-wire fans, and I believe the bilge blowers I plan on using are only 2-wires. Appreciate your input, thank you. Cotton

 

[highdesertranger]

exhaust cutouts do not seal 100%. IMO any floor vent needs to be air tight because of exhaust fumes while you are driving. highdesertranger

 

[CottonTexas]

exhaust cutouts do not seal 100%.  IMO any floor vent needs to be air tight because of exhaust fumes while you are driving.  highdesertranger

I agree to a degree.  Exhaust cutouts are designed specifically to seal exhaust, and depending on where your floor vent is located, you might get more exhaust going down the road through the cracks in the weather-stripping on the rear cargo doors than through a cutout - assuming your exhaust system is functioning correctly and not leaking directly below your floor vent.  I'd NEVER recommend using floor vents while idling, but sometimes you do need to idle, and that's when I would want to ensure my floor vents aren't seeping noxious gas into the chill-compartment while they're alleged to be closed.  I feel that the exhaust cutouts would seal well enough, but the problem still lies with how to get them to open and close (fully) automatically when the fans come on.  Thanks for your replies, Cotton

 

[galladanb]

Speaking of fan speed remotes...
Has anybody tried to make a DIY solution to a remote for fan speed, either wired or wireless???

MaxAir makes one for the 5100K and other models, but they don't sell them, one has to buy from a "DEALER"
like Camping World, etc... BUT, I'm thinking it should be fairly simple to DIY something...

 

[SternWake]

Some of the PWM speed controllers have 3 wires going to a potentiometer/rotary knob which controls fan speed. Only two of these wires really do anything, usually. A DMM set to ohms will register 2 wires as having no resistance between them

I can control my ceiling exhaust speed from bed as I put the potentiometer there and just extended the wires. My adjustable speed celing exhaust fan is a silverstone fm121 which comes with a potentiometer for speed control, I extended its two wires to reach where I put the potentiometer.

My silverstone fm181 that I use as an intake fan in a conversion van slider window, I put the loose potentiometer on the fan itself. It resides by my head when laying down so changing speed is convenient. That fan is practically silent on lowest speed, and i can direct or even stop airflow with the stiff curtain.

Wireless, no idea.

 

[jonyjoe303]

the pwm controller shown on the picture are the same I use on my swampcoolers. I only encounter electrical noise (very annoying at low speed) on one of the ones I used and I used at least 10 of them. They are very reliable will last you years. I use to put them inside the swampcooler near the fan but they get corroded when in presence of water. 

I used them on 120mm fans and also on the larger 10 inch car radiator electric fans (about 6 amps), they can easily handle the smaller fan you have. On the radiator electric fan they outlasted the fan which stop working after 1 year of daily use. For the price of around 5 dollars, they are a good deal.

 

[tx2sturgis]

Cotton have you actually hooked up that blower to 12v and run it yet?

Those things are pretty loud running at full bore and when you 'pot' them down to a quiet level they dont move much air at all.

Might be ok for you tho....I tried to make mine work but couldnt stand the racket.

I did consider mounting it on a pvc elbow under the van, but instead I ventilated the back door of my van and I use a fantastic fan.

Also, they are brush-type motors, not brushless, and so they make a lot of noise on AM-FM radio, as do the PWM controllers. If you like to listen to a radio at night with one of those running, well good luck.

If you buy an extra controller or two, you can recover quickly if one fails during hook-up or due to voltage transients from engine starting etc. They have no transient protection at all. I recommend putting a large electrolytic across the input, but still, no guarantees.

Not to mention if a new one comes in DOA. Which can happen, the QC on them is pretty lax.

 

[CottonTexas]

I appreciate your insight here.  I was thinking that they're gonna be pretty noisy, but I'm trying not to cut any holes in my roof, so a 3" hole-saw will be used to run these things connected to pvc pipe through the floor.  It's been recommended to mount them below the deck, and I still might do that, but I'll have to measure everything to make sure that it doesn't hang down too low.  At first I was gonna use 4" blowers, but I had to down-size when I changed component design.  Ideally, I'll be controlling ventilation with as few switches & knobs as possible, so I'm going to run both fans from a single controller and hope it'll be enough, though I know that in the future I may need to add more fans later (probably by the pair), in which case I may have to get back on here for advice on revisions.     Thanks for the heads-up on the radio interference - I can't say it will really affect my decision, but nobody likes unpleasant surprises, so I appreciate your input there.  Cotton