Fan-Tastic Vent mod from 3-speeds to 6-speeds

[flinchlock]

When I was trying to figure out what options I wanted in my Cougar, I asked a ga-zillion questions and one of my questions was regarding one or two powered vents... the answer was a resounding TWO.

So, I asked Ben to install two Fan-Tastic 4000R Powered Roof Vents.

But, after the first night I was not happy how loud the vents are even on the lowest setting. (I know, I know, how can a 60 yr old guy even heard them!)

I made a call to Fan-Tastic Vent Support about the fan speed and they sent me a kit to slow down the fan. The kit arrived in two days and on the third day I received a letter from Lorin Milks, Vice President of FF to tell me thanks for using Fan-Tastic Vents in my rig. The fan slow down kit is just a 4 Ohm 10 Watt power resistor with two pink 18 gauge butt connectors.

The kit instruction sheet (dated 07/06) that said to use blue 16 gauge butt connectors.

A revised instruction sheet (dated 01/08) said to use the pink butt connectors instead of the blue butt connectors.

 

[flinchlock]

Before...

After...

I added a switch that is simply connected across the added slow down resistor to return the fan to the original speeds. Round Rocker Switch #275-015 + 3/16" Quick Disconnects #64-3132

Hint: Use a "step" drill bit for the switch hole.

 

[flinchlock]

I decided to try different resistors to see if the fan could be a little slower over the upper bed area.

I choose a 8 Ohm 20 Watt Resistor. 8 Ohm 20 Watt Resistor #271-120

This Excel sheet shows the different values of resistors I tried and the current/voltage/power they used.

The added resistors had the following temperature readings (using a digital clamp on temp probe) in my closed barn...

1) Barn readings at 6 PM Temp = 91°F and Humidity = 29%
The 8 ohm resistor AND the 4 ohm resistor varied between 124°F and 125°F
2) Barn readings at 7 AM Temp = 65°F and Humidity = 48%
The 8 ohm resistor varied between 103°F and 104°F
The 4 ohm resistor varied between 101°F and 102°F
Mike

 

[flinchlock]

FYI...

Yesterday, here in Michigan, I saw a Pontiac Trans Sport with a Fan-Tastic Vent installed IN the rear roof!

Mike

 

[davinski]

Wow, this is cool.
I was wondering how to slow the FF down so that it could use very little power to slowly exchange the air in the camper and keep the condensation down. This may be the ticket.

I have not looked at mine yet, but could we just replace the 3 position switch with a variable resistor and then just have infinite selections instead of just 3 speeds?

I wonder if FF has every done that. I know some of the competitors have Variable fan speeds...

Anyone try this?

Dave in Seattle

 

[flinchlock]

I have not looked at mine yet, but could we just replace the 3 position switch with a variable resistor and then just have infinite selections instead of just 3 speeds?
There are just a few screws you can remove from inside the camper (none outside) so you can see the 3 speed switch. It appears to have a few coils of nichrome resistance wire and I am "assume" it relies on the air flow to keep them cool.

I am guessing a solid state variable switch would be the best since there is quite a bit of power to handle.

A word of caution, even though FF calls the white wire ground... IT IS NOT ALWAYS GROUND, it depends on if the fan is "IN" or "OUT". Trust me, pretty easy to smoke that nichrome wire!

Mike

 

[Dave Johnson]

Resistors have been used to slow DC motors for many decades. First one I remember was on my grandmother's 1953 Chevy. A rheostat that controlled the fan speed on the (optional) heater. It ran HOT.

The modern way is electronic control. It's called Pulse Width Modulation. As the name suggests, a 12 volt pulse is sent to the motor. It lasts a very short time, and repeats very often. The length of the pulse can be zero to 100% of the interval. These are very efficient, and generate little heat.

For the true DIY'er:
http://solorb.com/elect/pwm/pwm1/

Pre-built or kit:
http://www.bakatronics.com/shop/item.aspx?itemid=383

I have no connection with either of these folks, and just found them on Google. But both should be able to supply the current needed for the FF.

 

[HERR42]

that why i got a shure-flow fan....it has a continously variable speed. not a low med hi.

and lo is slow.

 

[flinchlock]

that why i got a shure-flow fan....it has a continously variable speed. not a low med hi.

and lo is slow.
Thank you very much for that info.

That will help the next person wondering which brand of vent to buy!

Mike

 

[dsrtrat]

Pulse Width Modulation with Fantastic Fan

I tried a pulse width modulation board from Bakatronics. I used a 15 amp module just to be sure I had the load covered. Wasn't satisified with the results. Fan produced a high pitched whine at slow speeds. I removed the PWM board and used the 8 ohm resistor and switch modification. Works fine. Six speeds and no hum. Thanks Flinchlock for the tip.
Dsrtrat