Date: Tue, 5 Oct 2004 21:31:10 -0600
Reply-To: Richard A Jones <jones@COLORADO.EDU>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Richard A Jones <jones@COLORADO.EDU>
Subject: fridge fan report
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Here are observations on the refrigerator fan from
my recent experiences:
I had replaced the original fan which was getting very
noisy with a Valterra fan (Fridgemate equivalent) last
fall. This summer, for various reasons, I have had the
fridge out four times(!) On the third time, I replaced
that fan with a pair of Radio Shack muffin fans. They
are speced at 33 cfm each. I mounted them side-by-side on
a piece of angle alu and mounted that must below the
bottom fins. I thought that it was a pretty slick
configuration on my part. On reinstallation, I noticed
two big differences:
(1) the fans came on much sooner than expected.
(2) They ran continuously until mid-evening.
Last weekend I pulled the fridge (#4) and put the
Valterra fan back in.
Here are my observations and analysis:
The Valterra pushed much more (MUCH more) air against
my face than the pair of muffins fans, when hooked to
12V. Both fans seem to produce a "cone of air" movement.
I think that putting two muffins fans side-by-side
causes some interference and makes the cone larger--
moving less air over the center of the fins and thus
running longer before the sensor cools and shuts it off,
as well as moving less air totally.
Why did the muffin fans come on so much sooner? I think
they actually blocked the natural convection pretty
effectively. If you look at them, they have a frame and
then the blades are such that they cover the whole 360
degrees. So visually they are "opaque"--which means that
is the similar to the convection air.
Anyway, after putting in the Valterra (Fridgemate) replacement
back in, the fridge is back to "normal"--the fan comes on only when
much warmer and runs and cycles as it used to. Plus, the
internal fridge temp stays down and does not rise to 50 degrees
as with the muffin fans.
My conclusion: A pair of 33 cfm Radio Shack muffin fans is
BAD(!) The Valterra moves much more air by my informal
test and does not block the natural convection that is what
cools the fins 90% of the time.
I suspect that a single muffin fan might be better than
two, in the sense of aiming at the sensor better, but 33 cfm
(if that is what the Radio Shack fans really do) is not
enough. I'd stick with the Valterra rather than test this.
Mounting the pair of muffin fans somewhat apart might be
better then side-by-side, too, but again, I won't be testing
that!
This is not to say anything about the GoWesty fan which is
rated much higher cfms. I have no experience with the
GoWesty fan at all. But my advice, worth what you have
just paid for it, is to stick with the Valterra replacement
fan. Anyone with the GoWesty fan should report on it.
BTW--as I recall, I switched the orientation of the Valterra
bracket 180 degrees and drilled new mounting holes to make
it work, but it was a simple, obvious mod.
Here is a final observation: I played with a tiny
Radio Shack fan that some have mounted inside the fridge
to move air over the cooling fins. Well, the first thing
that that was obvious was that the "drip tray"--the white
plastic tray just under the fins--blocked the air flow from
the fan. I removed it (and the fan) and the fridge cooled
very quickly. How stupid could I be to have not noticed
before that that tray perfectly blocked the convection inside
the fridge? How many of you have that tray? What use is
it? Maybe only to put in when you are defrosting to catch
all that melted frost water? ;-)
Maybe nobody else has that tray. When I bought my Westy,
the fridge was missing several parts, so I had my RV guy
look up the microfiche for that model and then we ordered
everything I didn't have. So I got Barbie trays, another
door shelf bracket--and the white drip tray. Anyway, if
you have the drip tray, try the fridge without it!
YMMV....
Richard A Jones
Boulder, Colorado
PS: http://www.valterra.com/RV/rvmain.htm then pick
refrigerator fans. Coil fan, A10-2710VP. You have
to buy it from a retail RV dealer.
