Vortex II Vent Fan Reliability Improvement

[Blacklane]

I recently replaced my Vortex single-speed vent fan with the Vortex II multi-speed reversible fan. While installing the fan, I accidentally dropped the fan on to a soft bed. I was surprised to find that the fan had broken where one of the resistors was mounted to the printed circuit board.
The problem is that the big, heavy ceramic resistors are just soldered to the circuit board with no support.
Luckily, I am in the aviation electronics business, so it was no problem to repair the broken solder joint on the resistor, but I also realized that preventing future failures was a simple matter of under-filling the resistors. Components in aviation electronics are usually under-filled with epoxy to provide structural support to improve reliability. Wherever you can eliminate movement between components, you eliminate the possibility of stress fracturing.
To help prevent future failures in my fan, I under-filled the resistors with silicone caulk. This should prevent movement that will lead to cracking. Epoxy might have been a better choice, but would have been much more difficult to install into such a large gap. Plus it might have been too brittle and cracked itself.
In my opinion, this failure mode is inexcusable. It would cost nothing to re-layout the printed circuit boards such that the resistors could be mounted against the board to prevent movement. It is obvious that having the mass of the big ceramic resistors supported by nothing but printed-circuit board foil won't work for long in the bouncing, swaying environment of an RV.
If you have a Vortex II vent fan, I recommend that you remove the printed circuit board and apply some type of support to the resistors to prevent future failures. You will have to remove the fan speed switch by loosening the set-screw on the knob, removing the knob, then the nut behind it. Then the circuit board with the resistors and selector switch should come out.

[gijoecam]

Double-tap...

[gijoecam]

Thanks. For $10, I ordered two because I can always find another project for one of these!

[Blacklane]

Interestingly, the PWM controller I added to my Heng's vent hood works perfectly: Link http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28032353.cfm
It's adjustable and quiet throughout its speed range.

[gijoecam]

Blacklane wrote:
I ordered one of those reversible PWM controllers on ebay as well. I thought it would be perfect. I tested it on the bench with my original single-speed Vortex fan and immediately found two shortcomings:
1. it produced an objectionable whine at every fan speed.
2. when in the "off" position, it still drew several milliamps of current. To actually turn it off and prevent battery drain, I would have to add a second switch.

I'm sad to report the same results. I wired it up in the campground yesterday and on anything short of full power, it sings like a bad bearing! Utterly unbearable... Maybe that explains why heng uses resistors rather than a pwm unit?

Suggestions on a quiet one? I can handle wiring the reversing switch I guess.

[Blacklane]

The reversing switch can't go on the input, since the controller itself won't work with reverse polarity.

[gijoecam]

Bummer... Guess I'd better order the replacement just in case then...

Did you install the reversing switch on the input or the output of the pwm controller?

[Blacklane]

I ordered one of those reversible PWM controllers on ebay as well. I thought it would be perfect. I tested it on the bench with my original single-speed Vortex fan and immediately found two shortcomings:
1. it produced an objectionable whine at every fan speed.
2. when in the "off" position, it still drew several milliamps of current. To actually turn it off and prevent battery drain, I would have to add a second switch.

[gijoecam]

firestorm79 wrote:

Lynnmor wrote:

eBay, tons of them. I first tryed one that had a reversing already attached, but that one set up harmonics. If you get the really cheap one and a DPDT switch you should be good.

I had the same problem with harmonics on the integrated reversing. Swapped it out for a standalone PWM and a DPDT switch and it works like a charm.

Nuts... that's what I ordered... there were a couple slightly different designs... Hopefully the one I ordered won't be an issue...

[firestorm79]

Lynnmor wrote:

eBay, tons of them. I first tryed one that had a reversing already attached, but that one set up harmonics. If you get the really cheap one and a DPDT switch you should be good.

I had the same problem with harmonics on the integrated reversing. Swapped it out for a standalone PWM and a DPDT switch and it works like a charm.

[gijoecam]

Understood. The pwm circuit board I ordered includes a reversing switch and a pot, both of which are on short writes, so I can put the board near the air flow and the pot in the existing home for the power switch. (The original fan is feed from a switch on the vanity, so no need to maintain a power switch on the fan, and the reversing switch on the pwm also has a center-off position on it...)

[JesLookin]

Just a comment on how the circuit board was originally designed: Typically when a component is mounted in the manner that the big resistors were soldered to the circuit board, is that the resistors get very hot and the space below them allows air to circulate all around the resistor preventing the heat being applied directly to the circuit board.

That being said, a PWM circuit would have been a much better choice.

[gijoecam]

I figured out the switch while I was in the shower this morning... I've also found a couple of PWM speed controllers on eBay that I think will work (one has the reversing switch built in).

I'm also going to pick up another switch and some small LEDs to use as night lights/reading lights. We always use a battery-powered puck-light as a night light for the kids, so this will be the next evolution of that (and I won't keep knocking it off the counter when I'm in there!)

ETA: My only concern is with the speed controller not being weather-proof.... We have a MaxxAir cover over the vent, but during a heavy storm there.s always the potential for some moisture to get in there. I'm not too concerned as the speed control will be at the end farthest from the opening, but it would still be nice if I could coat the unit in potting compound or something similar...

[gijoecam]

Resurrecting this... can you please list the part numbers you used for the pwm and switches? I can get a smoking deal on the original vortex fan from my local shop, but I can't, for the life of me, figure out how to use a dpdt switch to reverse the direction... (I need to sit down and draw it out)

A schematic would help too, if it's not too much trouble... Thanks!

[JBees]

Lynnmor wrote:

Blacklane wrote:
I have to say I love this idea. I had not considered PWM controllers since I had no idea they were so cheap.
It looks like Lynnmor's set-up has a power switch, a reversing switch, and a speed potentiometer. However, it looks like the PWM gets power all the time. I think I'll switch power to the PWM since they draw a few hundredths of an amp in standby. I think I can perform the power and reversing functions using the same switch if I use a 3-pole, double-throw, center-off switch.
I'm also thinking of replacing my range hood exhaust fan with a more efficient computer fan plus a PWM controller to achieve higher performance with lower noise.

I used the original on-off switch as a master that kills all power. That way there is no need to fiddle with speed or direction until I want to change it. In addition I have a master wall switch to accommodate my last short wife.

Can you give numbers and where to purchase? How about a write up, with diagrams? Thanks