To: David.Zabowski@azalea.learning.cs.cmu.edu, smithd@software.org,
        bovik@cs.cmu.edu
Subject: Re: Whole house fan - recommendation? 
In-Reply-To: Your message of "Mon, 22 Jun 92 14:11:00 EDT."
             <709236692/stork@AZALEA.LEARNING.CS.CMU.EDU> 
Date: Thu, 02 Jul 92 11:33:06 -0400
Message-Id: <18592.710091186@carrot.psc.edu>
From: ngoddard@carrot.psc.edu


Slim pickings from collective net-wisdom.

One person recommended getting belt-driven rather than direct drive -
with the latter the motor vibration is transmitted to the fan blades,
so it is noisier.  All the bigger fans (over 5000 cfm) seem to be
belt driven judging by the results of my inquiries.

One person said he has a Sears whole house fan, from the catalogue,
in his kitchen window and he says it does a great job.

As far as I can tell most heating/cooling contractors know next to
nothing about these fans - all they want to sell is A/C.  I did talk
to one electrical contractor who has a whf in his house.  He said it
is no more noisy than a refrigerator.  He recommended fans by Dayton,
Fasco, and Emerson in that order.  They seem to be 2 or 3 speed, with
the lowest speed about 60% of the highest.  He disrecommended trying
continuously variable controls, something about making the motor
vibrate (my guess is the control just clips the waveform, setting
up lots of high frequencies in the signal).  This guy is Steve Nydes
who owns Best Electric in Squirrel Hill at 521-1053.

Readers Digest do it yourself manual has sizing info.  Basically you
compute the volume to be vented and select a fan which can move 2/3
that volume in a minute (or the entire volume if you live in the
South).  For me this means I need a 10,000 cfm fan.  Then you have to
worry about venting out the roof or gables.  The rule is one sq. ft.
for each 750 cfm.  So I need about 13 sq. feet of vent, which I think
means I need to use gable vents.

Nigel