Tales from a Ventilation Lunatic

[Roadtripp]

I’m stoked by try the strong 282 cfm fans 12-24 volt fans. Thanks for the suggestions. I’ll order a couple and test the amperage. See if it really is 1.1 amps. And I’ll try the buck boost converter you linked. I’ve not tried a buck boost before so it’s definitely a learning curve. I was wondering about 3 wire and 4 wire fans and which are PWM. I read that a 3 wire inculudes a sensor wire that tells the computer processor the fan is running or not. And possibly rpm?
Will post the results. Obviously without power hungry air conditioning it’s crucial to have ventilation.
Another thread is about insect exclusion. This season I’m planning ahead. My first season full time dwelling there was a issue with black flies. I didnt plan ventilation so the windows were open. And no roof vent . It was awful lol. Not going back there again.

[sternwake]

The one enclosed buck boost converter linked is rated atonly 2 amps, and I have my suspicions that the 282CFM fan can move that much air for less than 2 amps.

I'd recommend experimenting with a buck boost converter rated for higher amperage first, then testing just how much the fan can draw,

All my door windows open, I used to have screens for them, but passive ventilation is only adequate when there is wind.
Keep us updated on the results.

[Roadtripp]

Yes , I opted for a 8 amp buck boost converter from Amazon as I may be powering two of those 282 cfm German fans from one 8 amp converter. And I ordered three of the 282 cfm fans from Surplus Center to have a extra for the cargo van ventilation. I also got a tiny computer muffin fan to cool the converter if necessary. They are only $1.82 at Surplus Center.
Time to finish the main power feeds and distribute power for the fans and what not. On the Motorhome I built a 24 volt solar energy system. A 30 amp Newmar 24 to 12 volt converter feeds 8 gauge conductors back into the RV. And a inverter feeds 120 volt AC into the RV main panel. That’s as far I’ve gotten. I’m searching for a decent Blue Seas fuse block and distribution center I had this Spring but is waylaid. . The main converter is roughly 400 watts available at 13.6 volts. I thought maybe of getting into HAM radio someday. But venting (cooling), heating, cooking, hot water, compost toilet, etc, come first.

[sternwake]

Looking forard to your data on the amp draw and impressions of airflow.

If these fans are that powerful for that amount of amperage, and respond nicely to voltage based ( or PWM based) speed control, then I can redesign my intake fan shroud around them and get around 400 more CFM of airflow, and then relocate those 120MM industrial noctuas to my front window Exhaust for better airflow at half the wattage consumed.

Here is a 25 KHZ PWM DC motor speed controller that you might also want to consider over the voltage BUck/boost method of speed control.

https://www.amazon.com/KNACRO-Speed-Cont...ller&psc=1

Pretty easy to extend the potentiometer wires, for more distant relocation of it.

The voltage buck boost potentiometers on the circuit boards need to be removed, wires soldered to them and the right resistance pot attached at the end for ease of use.

Other than the Whining caused by the cheap LED PWM Dimmers( 13KHZ) and the fact that i Dimwitted my previous 21KHZ motor speed controllers, blowing them up with reversed polarity, i am not sure why i did not go with PWM speed control on the recent and previous 92mm fan's red black fan input wires, other than I ordered 5 of the 3a voltage buckers and could employ them.

The 21Khz PWm motor speed controllers I fried with reverse polarity, were rated at 8 amps and had just two of those heatsinks, where the product linked above has 6, and 4K more hz

[tx2sturgis]

I bought two of these fans (ebmpabst) last year at a hamfest, for about $10 a piece if I remember correctly.

They are similar to the fans linked in post #57, but these are rated at 15w 24v, 600ma at rated voltage. Most of the time I choose 24 volt ball-bearing fans for my 12 volt sources. They run quietly and just about forever on 12-14 volts. 

At about 13v they pull about 250 mils, and powered directly (no controller, no battery) from a 20w solar panel the current is around 500-550 mills depending on sun angle, and at around 21 volts under load the panel is just loafing along. The fan spins fast at 21 volts, moving a lot of air for 'free'. The fan was spinning in the photo, but the camera shutter was fast enough to 'stop' the blades in the picture.

These are 'impedance protected' fans, meaning they will start easily with a LOW starting amperage...the amperage is increased as speed is slowly increased, there is little to zero extra surge as they are powered on. Which (for me) also means that the fan will easily start when powered directly from a solar panel as the panel is exposed to increasing sunlight, the rotor will not 'stall' while sipping current from a panel at very low output level.

       

[Roadtripp]

Thanks SW and Tx2. I’m also ordering that 25 KHZ PWM speed controller you linked in #64 . I have a dc clampmeter that seems to be somewhat accurate for amperage readings. I’m hoping the fans perform well.
When connected directly to a solar panel have you had fans fail ? Can a panel be too big and supply too much unregulated power. Or is it self regulating?

[tx2sturgis]

Well, if you hooked up a 12v fan to a 20 watt panel with VOC of 22 volts, then yeah, you might see that fan fail really quick. 

But a 24-28v fan can easily handle the VOC of this panel at about 22v.

No problemo.

Many solar-powered attic ventilator fans operate exactly the same way.  As long as components are matched and compatible, it works fine.

[sternwake]

I've not tried to feed a fan directly from a solar panel, most of the reason being I would rather have manual full control of a fan, sun up or sundown.  

I have run some 12v fans well in excess of 20 volts, but not for very long.  They still work, but I'd not recommend doing this intentionally.



I have fed a '45 watt' 12v heating pad directly off of a 100 watt panel and it would go up into the 17v range and about 72 watts with the panel aimed at the sun mid summer.  This wound up damaging parts of the heating pad which were not in direct contact with the sunshower bag.

---

It appears the first warranty replacement Noctua 3K rpm industrial nf-f12 fan has also failed, and my confidence in this particular fan model is shot, so these 6" pabst fans might see employment well before summer, and I am looking forward to how they respond to speed control measures outlined in previous posts, mostly the amperage consumed  at 28v.

I've not yet pulled the intake shroud to inspect the 'failed' fan, but I suspect it is not simply a power delivery issue, but component failure.

To top this off, my Silverstone fm121 also decided to quit.  This fan I have previously resoldered the power wires to the circuit board, then covered the solder joints with dielectric grase and put back into use, some 4 or 5 years ago.  
When I pulled this non working fan yesterday, I saw NO dielectric grease and the positive wire practicaly crumbled with the q tip and rubbing alcohol applied.  Perhaps i was delusional about having applied the dielectric grease, or perhaps it thinned out and drifted off with heat and the UV light which made it through the tape.
I've not yet delved into this fan further.  This fan's hub saw direct sunlight most of this previous summer when I had the mushroom vent above removed, the white duct tape I had covering the wire entry was brittle and dried out.

If i can sucessfully resolder new wires to the CB, and return function to this silverstone fm121 fan, it will likely be approaching the constant use for 9+ years and if I cannot return it to function, the easiest thing to do would be to order another.

So anyway I will now have to eat some crow, reverse myself and have to recommend that the industrial noctua 3k rpm nf-f12 fan be avoided.  Even if Noctua keeps sending me new ones under warranty, their failure and replacement is not without effort, and they could compromise Fiona's safety/comfort which is not acceptable.

These particular  Noctua fans are IP52 rated, but I can see no covering of the solder joints where the wires enter the circuit board. and have applied no Amazing goop or similar over them, which has proven to be an issue on almost every other fan.  I would recommend that if this area can be accessed on the pabst or other computer fans, that these joints be deprived of oxygen and moisture by grease or Amazing goop or similar.

[sternwake]

Ok the Silverstone fm121 is beyond hope. I reattached the positive wire to the circuit board, and could get it to spin up to a pulsating 1/2 speed for a few seconds, and then that smell of failed electronics devoid of their magic smoke permeated the area.

The Autopsy revealed that there was lots of impacted dust surrounding the microprocessor chip and a diode and resistors, and the green circuit board covering was lifting off the traces.

This fan has been exhausting cooking gasses and the whole van for somethng like 9 years, so I certainly got my money's worth from it.

Ultimately I would like more ceiling exhaust power here, but the 4 inch opening will always be a limiting factor regardless of how powerful a fan I have up there. So until I reengineer some sort of rainproof vent with a low restriction presented to a powerful speed controlled fan, I am going to get another SS fm121 as installing will require just splicing 2 wires and turning 4 screws.

I do think I will take precautions regarding impacted dust and corroded wires at the circuit board though.

[sternwake]

The new SilverStone FM121 arrived  for 15$ from walmart.  The tracking number they provided was wrong, but it arrived well before the day they said is should arrive by.

Looks like they have changed the design slightly, the access to the wires in the hub is a bit different, and the little E or C clip or snap ring is different than the little  white plastic washer retainer used on my older SS fm121 fans.

I ground the tips of some cheapo Harbor freight needle nose plyers to get inside this clip and remove it.  If one does the same, be careful as this clip loves to go flying.  I was lucky to find it.

I removed the impeller from fanbody to close off the circuit board from possble dust impaction and hopefully to remove the possibility of circuit board corrosion from my salt air environment.  I filled in the area around the wire entry, as well as the bottom of the amber circuit board to the white fan body, with Amazing Goop's marine version, which dries incredibly clear as long as one does not keep moving it around after it leaves the tube and is in place.  The AG is is in place in these photos, sealing off the CB and wire entry.

By sealing off the circuit board in this manner, it might also cause the microprocessor chip and other components to overheat.  If the fan fails prematurely, I will know why.