Fan-Tastic Vent Speed Mod

[Patrick M.]

On the Casita forum someone mentioned that the Fan-Tastic Fan company would send you a resistor to mod their fan to reduce the speed. Here are the instructions and resistor (4 ohm, 10 watt) they sent me. Great extra service from them! Don't know if they are still doing it, but call 1-800-521-0298 and ask for Tech Support.

Some people have put a similar 10 ohm, 10 watt resistor in their Casita stove hood to reduce its jet engine with success.

[Frederick L. Simson]

...to reduce its [b]jet engine with success.

I just keep the Fiber Stream too heavy for take-off.

[Pete Dumbleton]

Of course, the drawback to using a resistor is that it will still use as much power to move less air and turn the excess power into heat -- Not a major problem, however.

[peterh]

Of course, the drawback to using a resistor is that it will still use as much power to move less air and turn the excess power into heat -- Not a major problem, however.

As you increase resistance in a circuit the amount of current (amps) goes down (I=V/R . . . amps=volts/resistance). The fan itself probably doesn't have a lot of resistance, so electricity runs through it pretty easily, turning the fan blades as it goes through. Add a resistor into the circuit and the electricity doesn't flow through quite so easily, so the fan blades move more slowly and less electricity is used.

The downside is that both the fan and the resistor have to do something with the electricity that flows through. The fan uses the electricity to force air through; the resistor uses the electricity to make heat. So the resistor does waste some of the precious energy, but the total current drawn by the fan with the resistor in-line will go down.

--Peter

[Steve L.]

I like this mod. Power resistors shouldn't be hard to find at a local specialty electronics store (I have an RS Electronics store nearby. (12 watt 4 ohm) In the summer's I've camped in I've never had to use more than low before turning on the AC.

[Patrick M.]

As you increase resistance in a circuit the amount of current (amps) goes down (I=V/R . . . amps=volts/resistance).

I can confirm that Ohm's Law was upheld with this mod. Current in amps before/after adding the resistor: Low 0.89/0.66; Medium 1.17/0.80; High 1.47/0.91.

Low speed is now much nicer for in-trailer use.

[Chris C]

I did the mod yesterday and am very pleased with it. Worth the time. Now I can keep the fan on low at night to keep down the condensation and it'll really be on low instead of low-roar!

[peterh]

I think I'll make a mod like this, too. With our "big" 5th wheel there are times when running the fan on high is a durn good idea; I'll monster in a resistor and a switch so I can have a six speed fan.

Also, just having calculated out how much resistance the fan has, I'll make that a 4.4 or 4.5 ohm resistor, which is 1/2 the resistance of the fan motor; that'll give me six distinctly different speed settings instead of a near-overlap at the top speed with the resistor and bottom speed without.
--Peter