Slowing down a FantasticVent

Anything electric, AC or DC

Postby Arne » Fri Sep 19, 2008 5:38 pm

wonder why they sent a new motor... and the resistor? I can understand the resistor, but wonder if the motor has to be different also.
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Postby planovet » Sat Sep 20, 2008 9:02 am

Toytaco2 wrote:Planovet,

I got the email address to their Tech Department through the link on their web site. In my email to Fantastic Vent, I just told them I was installing a new Fantastic Vent in a custom made teardrop trailer and that I had heard it was possible to slow the fan down using a resistor. I then went on to ask them if they had the appropriate resistors available and, if so, what the cost would be. I also gave them my name, address and telephone No.

That's all I told them and they responded within 2 hours. They shipped the motor and resistor without further communications. I will check it out this weekend to make sure everything is "good to go" before I return my original motor to them. .

Mike


Excellent job! Thanks and let us know how it turns out.
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Postby Toytaco2 » Sat Sep 20, 2008 10:08 pm

Arne, I don't know yet if the motors are different or not, but, the wires coming from the new motor are different colors than the ones in my original fan. I still haven't put the motor in and hooked it up yet as I was working on cabinets all day. Maybe tomorrow.
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PWM Motor Control

Postby eamarquardt » Sun Sep 21, 2008 2:33 pm

I looked at the fantastic fan web site and the model I looked at drew less than three amps. The motor controller I referenced could control up to 30 amps, thus the large heat sink. The wasted energy of using a resistor to slow down the motor isn't a big deal on a small lightly loaded motor, as the fantastic fan. It is, however a, recipe for failure on larger more heavily loaded motors. Still, the pont of the forum is to share different thoughts and "push the envelope" in new directions. Me, I've got a PWM controller in stock and plan to play with a recycled radiator fan and the controller. I checked on prices and the least expensive fantastic fan is over a hundred bucks. I can proabably achieve the same (or maybe better results) for much less than half that. I'd rather save the bucks here and spend the money on something else I really value (three way refrigerator and rv range with oven for example).

Simply another case of "differenent strokes for different folks" or "have it your way" (Burger King, but I prefer the Carl's Junior Famous Star with cheese (no raw onion thank you, it give me gas) when I opt for a fast food hamburger).

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Postby Arne » Sun Sep 21, 2008 2:41 pm

true, I had the fantastic fan and swapped it out of no. 1 into no. 2 so I would not have to pay for it a second time... for me, the resistor is simply the easiest and cheapest way out. I really like the fan, but slowing it down is great, and not having to buy a second one was icing on the cake.
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Postby Oni » Wed Oct 29, 2008 12:31 pm

Hello everyone.

Been lurking for awhile. Thought I'd add this: http://www.resistorsonline.com/housed-c ... -wire.html

I've used these type resistors for applications like this one and I think they will work well in this application. You can mount them for a clean look to one of the spars and still have it in the air flow.
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Postby wannabefree » Sun Nov 30, 2008 11:15 pm

I posted this to another thread, but since I seem incapable of the simple task of posting a URL properly, I'll continue making a fool of myself here.

DC motors, lights, and similar stuff can be easily controlled with a pulse width modulator (PWM). They are characteristically more power conscious than just sticking in a series resistor or rheostat. There are a number of sources, but the one I like is a kit. Yes, if you can build a tear you can build this kit. Just put that 200W soldering gun away and use the little one from Rad Shack. Here are a couple of sources for the kit, and there are many others.

Now comes the part where I humiliate myself with another attempt to post a URL. Ready?

[url]http://www.arcade-electronics.com/detail.aspx?ID=17747[/url] and
[url]http://www.allspectrum.com/store/product_info.php?products_id=1488[/url]

Did it work this time? I hope so. BTW -- I do not endorse these sources. They just came up at the top in google. You can do your own search, if you like.
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Postby Leon » Mon Dec 01, 2008 1:28 am

While PWM is more efficient, it can cause a motor to exhibit a buzzing noise
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Postby wannabefree » Mon Dec 01, 2008 8:34 pm

That's true, a PWM can cause the fan to buzz because it is sending pulses to the fan, not pure DC. However, if the frequency is high enough you will never hear it and the fan won't know the difference between DC and pulses. This is a function of PWM design, and a well-designed PWM won't exhibit this problem. Ultimately the choice is yours. I'm comfortable with it because if it doesn't work right I can fix it. Not everyone is in that position. Nearly every modern power supply, from that running you TV to your microwave to charging your razor is based on PWM. How many people are complaining about it buzzing?

Just consider this an alternative to turning energy into heat.
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Postby Larwyn » Mon Dec 01, 2008 9:53 pm

wannabefree wrote:That's true, a PWM can cause the fan to buzz because it is sending pulses to the fan, not pure DC. However, if the frequency is high enough you will never hear it and the fan won't know the difference between DC and pulses. This is a function of PWM design, and a well-designed PWM won't exhibit this problem. Ultimately the choice is yours. I'm comfortable with it because if it doesn't work right I can fix it. Not everyone is in that position. Nearly every modern power supply, from that running you TV to your microwave to charging your razor is based on PWM. How many people are complaining about it buzzing?

Just consider this an alternative to turning energy into heat.


I'm still happy with the fan speed as supplied by the factory, which has been the number one supplier of vent fans to the RV industry for many years now. Resistor, or PWM power supply will use more energy than the fan alone. I do not care to waste battery reserve for the sake of "improving" on a proven combination of power consumption/air movement. If the fan is too loud, I'll turn it down or off. I'm sure I can snore louder than the fan on high anyway........... :lol: :lol: :lol:
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Postby wannabefree » Mon Dec 01, 2008 9:58 pm

The voice of sanity and reason gets the last word!

Man, that was so much better than "shut up."
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Postby Larwyn » Mon Dec 01, 2008 10:18 pm

wannabefree wrote:The voice of sanity and reason gets the last word!

Man, that was so much better than "shut up."


Yep, I had no problem with what you had to say. Just wanted to remind people of the option/advantage of leaving well enough alone. :thumbsup:
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Postby bluzharp » Wed Dec 17, 2008 12:39 pm

Larwyn wrote: Resistor, or PWM power supply will use more energy than the fan alone.


No, either device will result in less power consumption from the battery except in the case of the PWM at 100% output (minus the parasitic load of the controlling circuitry which is negligible for all practical purposes in this application).

Not trying to start trouble, just adding some clarification.
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Postby Larwyn » Wed Dec 17, 2008 2:58 pm

bluzharp wrote:
Larwyn wrote: Resistor, or PWM power supply will use more energy than the fan alone.


No, either device will result in less power consumption from the battery except in the case of the PWM at 100% output (minus the parasitic load of the controlling circuitry which is negligible for all practical purposes in this application).

Not trying to start trouble, just adding some clarification.


True, that statement was wrong, but any energy used powering/heating up that resistor or PWM supply is wasted energy from a limited supply (the battery). The fan will most likely also run hotter at the lower speed.
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Postby Arne » Wed Dec 17, 2008 4:33 pm

I think I will sleep better with the fan cycling off and on and running with less speed. the t/d now has a 10watt resistor in the fan and I like the speed it runs at. I also just got a 5 watt, but if the 10 watt works okay, I'll leave it in there.
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