From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Maxx Air vs. Fantastic Fan?
Message-ID: <1k08mu0njeg7ni7b2tdh02l7bp07b2ohd7@4ax.com>
Date: Wed, 21 Aug 2002 17:38:19 -0400

On 21 Aug 2002 11:28:25 -0700, sbourg@hotmail.com (S. Bourg) wrote:

>> I selected the Maxxair for my rig for two main reasons.  One, it moves a LOT
>> more air than a Fantastic Fan.  Second, I can use it in the rain.  This last
>> part is very important to me.  I can't imagine sitting in a muggy summer rain
>> storm without some ventilation.
>
>I don't see this from the specs - 980cfm vs. 920cfm - a 7% difference
>if accurate. In the field, mileage can vary, but I haven't seen any
>side-by side testing of this. The Maxxair DOES use more current on
>high (33% more) which is an issue if you're running it a lot.

Excellent example of why you can't compare specs without all the info.
Actually I'd trust sales specs about as much as I'd trust an RV salesman...
Among the things not stated, what ambient conditions? What head pressure? What
inlet pressure?  How far open is the vent lid?  What supply voltage?  Without
that info, some CFM figure quoted in a sales brochure is meaningless.  There
is an ASHRAE standard for fan testing (and another one from a trade group
whose name escapes me right now.) but I see no indication that Maxx employed
that standard.  No idea about FF.  A prime indication that they didn't is that
neither specify SCFM (standard CFM)

My subjective "back of the hand" test tells me that the Maxx moves a LOT more
air.  Just for shits'n'grins, I got out my hot wire anemometer and measured
what my fan does.  Under conditions of hotter'n'hell(100+), high humidity
(dripping), unknown supply voltage (on shore power) and the vent lid up as far
as it goes (the Maxxaire hood blocks it from fully opening, my Maxxaire
delivers 469 CFM on exhaust and 625 CFM on Intake.  The difference is the
motor's brushes are phased for the direction of rotation on intake and so runs
faster.

I suspect that this is perfectly normal performance.  Anyone have a FF who
also has an anemometer or air flow meter so we can compare actual numbers?

>We use a vent cover with our FF, so no extra mechanical complexity and
>just as useful in the rain as the Maxxair. Of course, we had to rely
>on Maxxair to supply the vent cover.
>
>What I like about our FF is it is inaudible on low inside the m'home
>unless you are directly under it. At that speed it also uses only
>about 1 Amp (despite specs) and can run day and night without an
>appreciable resource drain.

If you're quoting a current draw you measured, I suspect it is high.  Unless
you used an iron vane analog meter or a true RMS DVM that can handle both high
frequency pwm and high crest factor waveforms, your reading will be in error.
I have such instrumentation and know that the Maxxair draws barely 350 ma on
low speed.  A conventional DVM indicates > 1 amp.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Maxx Air vs. Fantastic Fan?
Message-ID: <g1h6mukti5e10n1aaqk6mjk463j2k02vsf@4ax.com>
Date: Wed, 21 Aug 2002 18:27:41 -0400

On Tue, 20 Aug 2002 19:12:27 -0700, "ben hogland" <benhogland@hotmail.com>
wrote:

>Curious that it's noisier though.. You're the second person to say that..  Hmm..
>

Just remember that there are folks in this group who think a Honda EU
generator is noisy....

Now my only experience with a fantastic fan is in playing with a few at RV
shows but I can't really tell a whole lot of difference in the sound when both
are run wide open.  Admittedly my head ends up right next to the FF :-) which
might influence my opinion.

The important thing to understand is that you'll almost never run either fan
at full throttle.  I keep my Maxx on the lowest speed setting most of the
time.  At anything less than about 3/4 throttle the gentle whine from the
switch mode speed control is louder than the fan.

I'm pretty immune to most noises but the sound of a fan running drives me
batty.  I couldn't stand the sound of the tiny little OEM fan.  And even after
I replaced the stove hood fan with a Rotron whisper muffin fan, I'm still
annoyed by the sound.  Interestingly enough, the sound of the Maxx doesn't
bother me at all.  I'll notice it if something calls my attention to it but
otherwise it's just part of the background.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Maxx Air vs. Fantastic Fan?
Message-ID: <uqtkmu4ata5lmtqi4r5cn6uqphgqo941uh@4ax.com>
Date: Mon, 26 Aug 2002 14:52:30 -0400

On 26 Aug 2002 07:41:40 -0700, sbourg@hotmail.com (S. Bourg) wrote:

>> If you're quoting a current draw you measured, I suspect it is high.  Unless
>> you used an iron vane analog meter or a true RMS DVM that can handle both high
>> frequency pwm and high crest factor waveforms, your reading will be in error.
>> I have such instrumentation and know that the Maxxair draws barely 350 ma on
>> low speed.  A conventional DVM indicates > 1 amp.
>
>Were you driving your fan with AC?
>
>Measured with a DVM on DC scales, paralleled by a scope for noise
>inspection. D.C. bench supply. Nothing but low-frequency low-level
>ripple out to 20 MHz bandwidth of scope, thus no reason to doubt the
>ammeter reading at any of the three speeds.

The speed control for a Maxxair continuously variable and is a pulse width
modulated unit that is unfiltered on its input.  This ripple was sufficient to
interfere with my E-meter and my 12 volt digital clocks until I built an LC
filter for the controller's input.  My Fluke 87 (true RMS, though with
significant crest factor and frequency limitations) and Fluke 88 are confused
by the mixed signal.  My FlukeScope (which computes the RMS value of a
displayed waveform among other functions) is not.  Neither is my 0.25% analog
iron vane lab ammeter.

I neither know nor care what instruments you have.  I do know that if you
simply slapped a handy DVM in series with the Maxxair, then your reading is
almost assuredly wrong.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Power vent
Date: Wed, 20 Aug 2008 11:31:55 -0400
Message-ID: <bmdoa4djhkb6lea2m3cgoocnooaddtqajb@4ax.com>

On Wed, 20 Aug 2008 07:03:32 -0700, Mickey <mickey@webster.com> wrote:

>Mickey wrote:
>
>
>Thanks for the replies folks.
>
>The praise for the Fantastic brand is surely worth something.  Wish
>their product's had infinite variable speed but maybe it not that big of
>a deal.

Have you ever noticed that the praise for the Fantastic company is always
about how they replace BROKEN stuff?  Key on BROKEN.  If a company charges 3
prices for a product then they can afford to give away parts.  Consider that
the Fantastic Fan has little more in it than a box fan that one can buy at
Wallyworld for under $20.

Even at that high price, one still can't use it in the rain without some
ancillary cover.  Nor can one leave it open unattended (yeah, I know about the
rain sensor.  If you trust that then you believe that the government is here
to help you.)

If Maxxaire hadn't screwed the pooch when they got rid of the infinite speed
control, I'd recommend them without reservation.  As it is, I still like the
concept better than any other fan I've experienced, good enough to make or buy
an infinite speed control if a variable speed controller can't be had from the
factory.

BTW, Maxxaire gives away replacement parts too but you never hear about it
because nothing ever breaks.

>
>Have had the MH for 12 yrs and this is the first time  we've really felt
>we'd appreciate a power fan.  High temps and humidity are not that
>common for us so I don't see the need for a fancy smancy model with all
>the bells and whistles.

I'm the same way.  If it blows and sucks and doesn't let the rain in and
doesn't make too much noise then I'm happy as a clam in sauce.

John