Refrigerator External Cooling Fan

[austinado16]

During my recent Dometic fridge testing, it was apparent that I needed an external fridge fan for better hot weather cooling.  I was having trouble finding info about the "real" RV fridge fans and like others here, installed a computer fan.  

I wound up picking one up from Radioshack that was 1-9/16" square, moves 7.7cfm and draws .13amps.  Total with the switch was about $32.

Yesterday I did more research and finally found that Valterra here in CA is the supplier of the "real" RV external fridge fans.  3 versions are available: A bare fan motor with a prop, seperate switch and 2 temp sensors for about $30.....and 2 versions that are mounted in plastic tubes, one of which comes with a solar panel for $60.

I couldn't find any tech info on them, so I called Valterra this morning:
[EDIT]
(After Wavery found my info to be suspect, I called Valterra back and got some correct figures for amps and cfm.  The info below is now corrected. Thanks Wavery!)

Their fans move 12.5cfm and draw .11amps.  However, the solar version only uses .10amps but only moves 1.2cfm
Here's one vendor for the basic fan version: Valterra External RV Fan

[Jim K in PA]

Yesterday I did more research and finally found that Valterra here in CA is the supplier of the "real" RV external fridge fans.  3 versions are available: A bare fan motor with a prop, seperate switch and temp sensor for about $30.....and 2 versions that are mounted in plastic tubes, one of which comes with a solar panel for $60.

I couldn't find any tech info on them, so I called Valterra this morning:

Their fans move 12cfm and draw .8amps.  If you use the lighted on/off switch that comes with the kit, that bumps your current draw up to 1.5amps.

Here's one vendor for the basic fan version: Valterra External RV Fan

Thanks for sharing the info Austin.  I am a few projects away from looking into these, but I was wondering what fans people were using.

[GregE]

Thanks for sharing the info Austin.  I am a few projects away from looking into these, but I was wondering what fans people were using.

I'm getting ready to do this on my pup and I plan on using an Orion fan, Model OD8025-12HB.  It's 3.15" square, 12v, .18A, and 40CFM.  

http://www.orionfans.com/html/od8025.html

Greg

p.s.  Price of the fan is $9.33 before shipping but I'm sure that wouldn't add too much to it.

[wavery]

During my recent Dometic fridge testing, it was apparent that I needed an external fridge fan for better hot weather cooling.  I was having trouble finding info about the "real" RV fridge fans and like others here, installed a computer fan.  

I wound up picking one up from Radioshack that was 1-9/16" square, moves 7.7cfm and draws .13amps.  Total with the switch was about $32.

Yesterday I did more research and finally found that Valterra here in CA is the supplier of the "real" RV external fridge fans.  3 versions are available: A bare fan motor with a prop, seperate switch and temp sensor for about $30.....and 2 versions that are mounted in plastic tubes, one of which comes with a solar panel for $60.

I couldn't find any tech info on them, so I called Valterra this morning:

Their fans move 12cfm and draw .8amps.  If you use the lighted on/off switch that comes with the kit, that bumps your current draw up to 1.5amps.

Here's one vendor for the basic fan version: Valterra External RV Fan

austinado16,

Are you sure that motor draws .8 amps? :confused:  That's huge :yikes: .  1.5A for the one with the switch doesn't sound right either. Just curious where you got those numbers??

[austinado16]

austinado16,

Are you sure that motor draws .8 amps? :confused:  That's huge :yikes: .  1.5A for the one with the switch doesn't sound right either. Just curious where you got those numbers??

Good thing you guys are asking questions because I'm new to all this and obviously have quite a bit of schoolin' to do!

Just called Valterra back (Wavery, I called them this morning and that's where I got my specs from).

This time I talked to a gal in "RV Aftermarket" parts.  Told her we were looking for specs.......

The universal mount fan (the one that's just a motor and prop on a metal bracket, and comes with lighted switch and 2 temps sensors):
.11amps
12.5cfm

The model in the round black housing is the same spec.

The solar model is:
.10amps
1.2cfm
(I questioned her several times about the cfm of the solar model and she said those figures are what she shows in several different spec sheets.)

So there you have it!

[wavery]

Good thing you guys are asking questions because I'm new to all this and obviously have quite a bit of schoolin' to do!

Just called Valterra back (Wavery, I called them this morning and that's where I got my specs from).

This time I talked to a gal in "RV Aftermarket" parts.  Told her we were looking for specs.......

The universal mount fan (the one that's just a motor and prop on a metal bracket, and comes with lighted switch and 2 temps sensors):
.11amps
12.5cfm

The model in the round black housing is the same spec.

The solar model is:
.10amps
1.2cfm
(I questioned her several times about the cfm of the solar model and she said those figures are what she shows in several different spec sheets.)

So there you have it!

Thanks for checking. I knew that didn't sound right. I have a couple of computer fans for mine and they 2 only draw .35A @ 64CFM
http://www.newegg.com/Product/Product.aspx?Item=N82E16811998127#spec

I never hooked them up for 2 reasons. #1 I haven't had any problems with the fridge not cooling. #2 .35 amps is a lot.

I will check on that little fan but for $30, I may just stick with my $5 computer fan :sombraro: .

[austinado16]

It looks like the computer case fans might be the better deal all around.  

-They are much less expensive
-They use just slightly more power .11a vs. .15 to .18a
-They move 3 times the air

In fact, looking at the Orion.com site (thanks for that link above) they've got a version that is:

22cfm (almost double the 12.5cfm Valterra fans) at only .12amp (compared to the .11 of the Valterras).  This fan might be the best overall choice and it's probably $9.

Guess I need to redo my mod as the Orion case fan will give me 3 times the airflow, at less amps and 1/2 the price!

[GregE]

It looks like the computer case fans might be the better deal all around.  

-They are much less expensive
-They use just slightly more power .11a vs. .15 to .18a
-They move 3 times the air

In fact, looking at the Orion.com site (thanks for that link above) they've got a version that is:

22cfm (almost double the 12.5cfm Valterra fans) at only .12amp (compared to the .11 of the Valterras).  This fan might be the best overall choice and it's probably $9.

Guess I need to redo my mod as the Orion case fan will give me 3 times the airflow, at less amps and 1/2 the price!

You are welcome for the link.

I just checked my system and I don't have that model in my system.  I would image the price would be similar to the one I'm installing so $9 is a good guess.  I do have 1 more of the 40cfm model in stock that I metioned before.

Greg

[austinado16]

You are welcome for the link.

I just checked my system and I don't have that model in my system.  I would image the price would be similar to the one I'm installing so $9 is a good guess.  I do have 1 more of the 40cfm model in stock that I metioned before.

Greg

Now that we have fan selection pretty dialed in, we should talk about fan location:

Should the fan(s) be located up top so they are sucking out the heat and pushing it out the upper louvers?  Or should it(they) be down in the bottom sucking in cool air and forcing it over the fins?

I don't know.......

Part of me says, mount it(them) down low and let their 20-40cfm blast cool air over the coils and fins which will in turn force the hot air out the top louvers.

The other part of me says mount it(them) right in front of the upper louvers and and let it draw 20-40cfm past the coils and fins....providing you have baffling in place that makes the airflow go through those coils and fins.

Your thoughts?

[wavery]

Now that we have fan selection pretty dialed in, we should talk about fan location:

Should the fan(s) be located up top so they are sucking out the heat and pushing it out the upper louvers?  Or should it(they) be down in the bottom sucking in cool air and forcing it over the fins?

I don't know.......

Part of me says, mount it(them) down low and let their 20-40cfm blast cool air over the coils and fins which will in turn force the hot air out the top louvers.

The other part of me says mount it(them) right in front of the upper louvers and and let it draw 20-40cfm past the coils and fins....providing you have baffling in place that makes the airflow go through those coils and fins.

Your thoughts?

If you place the fan on the bottom pointing up, you may stand the risk of the air just circulating within the box, having hot air just going around and around. You have no guarantee that any air at all will exit the box. If you put it in the upper chamber, pointing to the outside, you will be sure that all air that is moved, is circulated and exhausted.

I would even go as far as to cover any opening in the upper chamber except exactly where the fans blow out, to avoid intaking any air into the upper chamber from the outside. That way you are assured that all of the air exhausted is being taken in from the lower chamber and exhaust out of the upper chamber.

You must understand that once you have a fan running, you destroy all drafting effects (these fridges are designed to work off of drafting). If the fan is not installed in a manner that ALL of the air is exhausted out of the upper chamber, you could (conceivably) do more harm than good.

[austinado16]

Well.......

Looking at the installation that Valterra shows of their base model (fan motor with prop mounted to a sheetmetal base) they show it mounted in the lower left corner, down near the controls, and facing upward toward the right.

Wouldn't drawing in air through the bottom louvers and forcing it up through the coils and fins under pressure, force the hot air out the top since the back of the fridge is a sealed off "box?"

[wavery]

Well.......

Looking at the installation that Valterra shows of their base model (fan motor with prop mounted to a sheetmetal base) they show it mounted in the lower left corner, down near the controls, and facing upward toward the right.

Wouldn't drawing in air through the bottom louvers and forcing it up through the coils and fins under pressure, force the hot air out the top since the back of the fridge is a sealed off "box?"

Not necessarily. The air could just as easily blow up to the top of the box and return right back to the lower box, to again be blown back to the top.

Why do you think that any of the air would exit the top? I don't see any reason for it to do so.

Now......if one was to place the fan on the lower door, facing inward and block off the remainder of that door so that no air could escape through the lower vents, then you would have a positive intake that would cause pressure in the lower box that would be forced to exit the top louvers because the air would have no other route of escape. However, I still maintain that the best option is to have an "Exhaust" fan in the upper box.

Keep in mind that your main goal is exhausting heat, not necessarily moving air over the coils. If the air is exhausted at a more rapid rate, air flow over the coils is a natural bi-product. If the air blown over the coils is merely sucked back down to the fan and recirculated, you may only be blowing (ever increasing) hotter air over the coils again and again.

Think of it like the exhaust fan in a bathroom. If one were to merely cut a vent in the ceiling and place a fan on the floor, pointing up, very little air, if any would escape through the hole in the ceiling. Most (if not all) of the air would merely circulate inside the room. Now... if you were to mount the fan in the window, facing in and the remainder of the window sealed off, with the bathroom door closed, the air would have no choice but to exit the hole in the ceiling because you have created a positive pressure in the room. However, there is a very good reason that bathrooms have exhaust fans in the ceiling, pointed up. They create a vacuum in the room and draw air into the room from any source available.

[kathybrj]

This was our setup on our 2002 Utah

http://kathybrj.tripod.com/id9.html

There was a significant difference in the cooling of the frige after the installation of this fan.

[GregE]

Now that we have fan selection pretty dialed in, we should talk about fan location:

Should the fan(s) be located up top so they are sucking out the heat and pushing it out the upper louvers?  Or should it(they) be down in the bottom sucking in cool air and forcing it over the fins?

I don't know.......

Part of me says, mount it(them) down low and let their 20-40cfm blast cool air over the coils and fins which will in turn force the hot air out the top louvers.

The other part of me says mount it(them) right in front of the upper louvers and and let it draw 20-40cfm past the coils and fins....providing you have baffling in place that makes the airflow go through those coils and fins.

Your thoughts?

How about 2 fans?  One blowing up at the coils from below and one at the top blowing out.

[AustinBoston]

I would even go as far as to cover any opening in the upper chamber except exactly where the fans blow out, to avoid intaking any air into the upper chamber from the outside. That way you are assured that all of the air exhausted is being taken in from the lower chamber and exhaust out of the upper chamber.

You must understand that once you have a fan running, you destroy all drafting effects (these fridges are designed to work off of drafting). If the fan is not installed in a manner that ALL of the air is exhausted out of the upper chamber, you could (conceivably) do more harm than good.

Another possible risk with doing this (specifically blocking the upper chamber except where the fan is) is forcing too much air through the burner portion of the fridge.  I believe these are designed to absorb as much heat as possible as the heat from the flame slowly rises.  If you block the upper vent and put a fan on it, you will be sucking the hot exauhst fumes out at a point where you need things to be hot in order for the fridge to work.

It may also increas ethe risk that the propane flame will blow out.

Austin