Refrigerator cooling fans

[Kurt Horvath]

Me to Gregg,I cut and pasted this from my post 33990

Photos of Exhaust Vent Fans are in my album , (bumpersbird) bottom of
page two and top of page three.

The goal is to move air past the cooling coil mounted on the rear of
the fridge, in my case a Dometic RM 7030. I have an angled setup
with an enormous space behind the refer. It is recommended that
there be no more than 1" a space behind the fridge to facilitate
convection for cooling the coils. Well I'm not one to reinvent the
wheel so I wasn't going to pull out the fridge to build a baffle
system, the recommended fix.

This won't be so much of a problem for you if your fridge is
1" or less from the wall behind it. The origonal fan and snap
thermostat set up should work good if it's all there and working.

To move a sufficient amount of air past the coils. You have two
choices you can suck or blow. Blowing is not recommended, but it
works.

Greg's system is set up this way and after a little tweeking it
works fine.

So how do you suck enough air volume past the coils to make a
difference? I not an engineer so I went for POWER!

You know the old saying. Put enough thrust behind anything and it
will fly.

I mounted 5 - 130 CFM computer fans inside the flue vent on the
roof.

http://autos.ph.groups.yahoo.com/group/W...tos/view/7
006?b=29

I got a marine style switch with a four switch/breaker combo. I
chose waterproof because I mounted it on the cabinet near the sink in
the bathroom and because its high quality and most of all because it
looks cool.

http://autos.ph.groups.yahoo.com/group/W...tos/view/7
006?b=32

I tagged into the 12V power leading into the fridge.

http://autos.ph.groups.yahoo.com/group/W...tos/view/7
006?b=30

Not a big draw for the fans and the fridge doesn't draw anywhere
near the 20 amps supplied to it. I used 2 of the 4 switches leaving
2 for future use. I wired the switches, #1 runs 2 fans, #2 runs 3
fans so I have the capability to run 2 fans @ 260 cfm, 3 fans@ 390
cfm or 5 fans@ 650 cfm.

Yes if you're standing near the access hatch you know its working. On
a calm day it will suck in cigar smoke in from 12" to 14" away.

I also mounted 4 fans in the fridge that blow air across the cooling
fins inside the fridge and of course they circulate the internal air.

http://autos.ph.groups.yahoo.com/group/W...tos/view/7
006?b=33

They are powered from the internal light assembly and mounted in
pairs they are quite nice. I got them from a guy on e-bay. Once you
see these little jewels you'll want them to. I check e-bay for this
guy and he's not making any fans at this time

The only problem I had was getting the wiring up to the fans. I used
a piece of pvc pipe I don't remember the size I just grabbed some
pipe that was laying around the barn and some mounting clamps,
inserting the require wires into the conduit before mounting the
conduit to the wood walls.

http://autos.ph.groups.yahoo.com/group/W...tos/view/7
006?b=31

I poked a hole up through the protective
screen in the flue vent, keeping it smaller than the diameter of the
pipe so it has a good grip on it. I had to drill one hole through the
wall to run the wires into the bathroom. A glob of silicon sealed the
hole and holds things firmly to prevent chaffing. I also used wire
loom where possible. Problem solved.

So far so good, this summer will tell if its working as well as I
think it will. I have already had to set the thermostat up to keep
everything on the lower shelves from freezing.

Is it noisy? Yes
Is it bothersome? Somewhat
Choice between noise and cold beer? Only you can answer that.

The fans are the big computer fans 4.7" @130cfm. There are fans of
this size that have a lower cfm and are much quieter to operate. I
have used these same fans to replace the blowers on some of my
heaters and they are quiet compared to the fridge set up. The only
thing I can think of is the fridge cabinet is hollow it may amplify
the noise.

This post is a little long and may not help a lot in your
application, but if you have a big space behind the fridge this will
work.

Kurt Horvath
95 PT-42 WLWB








--- In WanderlodgeForum@yahoogroups.com, "Gregory OConnor"
wrote:
>
> I dont think the advantage is cool air over the coil as much as it
> is removing hot air from the compartment. heat is a necessary part
> of Einstines amonia evaporation process and it is important to
> maintain a gradual cooling. I put a fan ducted to blow in the
> compartmet but others (I think Ryan or Scott) have a fan at the
> exhaust which would also remove the chance that blowing in will
> pressurizing the compartment and push un burned lpg into the bus.
>
> GregoryO'Connor
> 94ptRomolandCa
>
> --- In WanderlodgeForum@yahoogroups.com, "Chet Geist"
> wrote:
> >
> > Thanks to all for the advise. I did jump the snap thermal switch
> on one of
> > the fans and it runs fine. The refrigerator seemed to cool a
> little better
> > this afternoon, but that was just a short test with only 95 degree
> > temperature outside. I will probably bypass the thermal on the
> other fan
> > soon and see if that is a good solution. I will also pull one of
> the
> > thermal switches and see if I can get a number or something off
of
> it and
> > then buy two new ones.
> >
> > Have been packing today to go to the Texas coast on Thursday and
> wouldn't
> > you know it here comes Ike. May have to change plans again.
> Dolly screwed
> > up the last trip.
> >
> > Chet Geist
> > 1981 FC33, Austin, Texas
> >
> >
> > -----Original Message-----
> > From: WanderlodgeForum@yahoogroups.com
> > [mailto:WanderlodgeForum@yahoogroups.com]On Behalf Of joepat50
> > Sent: Monday, September 08, 2008 7:35 PM
> > To: WanderlodgeForum@yahoogroups.com
> > Subject: [WanderlodgeForum] Re: Refrigerator cooling fans
> >
> >
> > You could try jumping them out and see if the fans start. If
not
> the
> > fan may be NG.
> > If the switch is bad I got a dozen off ebay for a fan to cool
the
> > charger compartment where Im putting an inverter. Supposed to
> close
> > at 45 dC or about 115dF. If you want one let me know and I'll
> send
> > one out...
> >
> > /Joe
> >
> > --- In WanderlodgeForum@yahoogroups.com, "chetgeist"
> wrote:
> > >
> > > Behind my refrigerator are two small 12 volt fans that have
12
> volts
> > > to them. They are equipped with a small button thermal
switch.
> I am
> > > assuming these fans should come on when the temperature
behind
> the
> > > refrigerator gets above a certain temperature. Mine never
seem
> to run
> > > even when it is 100 degrees outside and the sum is shining on
> that
> > > side of the coach. Does anyone know the reason why they do
not
> run?
> > > Does anyone know at what temperature these button thermal
> switches
> > > kick in? Yes I have the switch in the galley set to "on".
> > >
> > > Chet Geist
> > > 1981 FC33, Austin, Texas
> > >
> >
>