Reply
 
Thread Tools Display Modes
 
Old 08-21-2010, 04:50 PM   #1
Member
 
Join Date: Dec 2008
Location: Salt Lake City
Posts: 42
Norcold performance improvement

From time to time I've periods where my 3.7 CF frig (the DC 0051) would not cool below about 50 degrees, even if running constantly. I'd pull it out and it would do fine on the bench.

As I said in a previous post http://www.sportsmobileforum.com/vie...p=45922#p45922, the Norcold manual for the frig says the small external fan should come on when the air around the frig exceeds 90 degrees. I checked mine by putting the frige in my sauna and slowly raising the temperature. The fan did not come on until it was about 125 degrees.

The heat that is removed from inside the frig needs to get dumped via the coils into the space behind the frig. When the temperature difference between the coils and the surrounding air is not much, the heat transfer is almost non existent so the frig runs continuously but it can't get rid of the heat.

To minimize that problem you need to maximize air circulation across the coils. SMB usually provides a very tight enclosure, with virtually no space on the sides. The bottom of the frig is about 1/2 inch off the shelf, and there is maybe 1 inch across the top. Air circulates by convection, and should be "helped" by the fan if it gets too warm.

The frig fan is located just below the compressor as seen below.



If the van is very warm inside the efficiency (ability to do heat transfer) is very poor. I put a thermometer with a probe behind the frig and saw that the temperature climed a good 20 degrees or more in that space when the frig kicks on.

I modified my system to increase the air flow by two methods: First I hard wired the frig fan to a switch to my 12 volt system so I could turn it on well below the auto activation temperature [Again, the manual says it is programed to turn on at 90, but my test indicated is came on at 125 degrees.]

I also cut a special opening into the support shelf behind the frig (directly below the compressor and the coils) and added a second small, very quiet fan to further increase the air flow. In my case I have a drawer below the frig, with open space at the back of the drawer which goes down to another space with my espar and a open return air. The new fan pulls air in from the floor up behind the frig and across the coils, and out.

I drilled a set of holes based on the layout of a 4" case fan, as seen in the next photograph.



The zip ties were used to "hang" the fan, and were later pulled tight to slightly compress the gasket.


The next three photos show the fan installation, which I did using a foam rubber gasket and zip ties, to help isolate vibrations.







Here are the fan specs, under the "Silent 12" column. Notice the decibels are only 20, and the current for the new fan is 0.08 amp (not an issue when the sun hits the solar panels).


Both fans are controlled by a DPDT switch which is ether OFF, one fan on, or both fans on. I kept the temperature sensor in place so I can monitor the back side space and the effect of the fans.

Its no fun taking a trip into the boondocks, wondering if your frig will do its job. I have had no problems since this modification, even in very hot whether.
Steve
__________________

__________________
2006 EB 6.0 Diesel, custom gaucho,
Espar hydronic and heat, 2 Solara panels,
Trojan F&R, ARB lockers, Warn winch.
BACKRDS is offline   Reply With Quote
Old 08-23-2010, 09:32 PM   #2
Member
 
Join Date: Jun 2008
Location: Draper, ut
Posts: 99
Re: Norcold performance improvement

that's a good idea. i might have to copy this. did you consider putting a thermostat on it reather than a hard-wired switch? my fridge seems to run pretty well, but i do have the space for this. thanks for posting it....nice job.
__________________

__________________
Joe Skrivan
E-350 V-10; Penthouse, Custom Interior
skrivan is offline   Reply With Quote
Old 08-24-2010, 04:00 PM   #3
Member
 
Join Date: Dec 2008
Location: Salt Lake City
Posts: 42
Re: Norcold performance improvement

Quote:
Originally Posted by skrivan
that's a good idea. i might have to copy this. did you consider putting a thermostat on it reather than a hard-wired switch? my fridge seems to run pretty well, but i do have the space for this. thanks for posting it....nice job.
I didn't think about a thermostat but that would be easy to do. Your choices would be to use a conventional thermostat behind the frig, but you wouldn't be able to access it. There are also styles with a remote "bulb" that could work and still give you access to tweak to the set point.

I didn't mention in my original post that the cooler environment behind the frig means that it cycles off quicker, although I haven't quantified that. If I'm away from the van on a hot day I usually run both fans; but at night I usually just run one, or none.

Steve
__________________
2006 EB 6.0 Diesel, custom gaucho,
Espar hydronic and heat, 2 Solara panels,
Trojan F&R, ARB lockers, Warn winch.
BACKRDS is offline   Reply With Quote
Old 08-24-2010, 09:18 PM   #4
Senior Member
 
jage's Avatar
 
Join Date: Apr 2007
Location: Franktown, CO
Posts: 7,600
Re: Norcold performance improvement

When I hear manual fan switch, I can only think battery draw. The fan that comes with the fridge has got to be terrible.. better than warm beer no doubt. My problem with the Norcold is consistency. I've had to go to an inside thermometer and play amp with the setting knob on front. Keep us updated on the effectiveness.
__________________
and then
everything changed
jage is offline   Reply With Quote
Old 08-24-2010, 11:26 PM   #5
Senior Member
 
DisabledExplorers's Avatar
 
Join Date: May 2009
Location: Phoenix, Arizona
Posts: 227
Re: Norcold performance improvement

This is one reason I went with top loading National Luna offroad fridge...not only are they very efffecient but they also handing the space confines well.
I'm at work so can't attach a pic but will when I get home.
__________________
Go out and play in the dirt!
DisabledExplorers is offline   Reply With Quote
Old 08-25-2010, 11:03 AM   #6
Senior Member
 
SheepShagger's Avatar
 
Join Date: Apr 2009
Posts: 340
Re: Norcold performance improvement

That style fan current draw is quite low, but as Jage said forget it's on, and it's still an extra load. Be careful with thermostats, many cheap ones will constantly draw the power needed to run the fan, but when not running the fan will just convert the power into heat. So no gain really except noise.

Couldn't you simply wire it into the existing fridge fan through a switch? That way you can switch it to just come on with the fridge fan, giving it extra cooling, or off all the time (night)?
SheepShagger is offline   Reply With Quote
Old 08-27-2010, 03:56 PM   #7
Member
 
Join Date: Dec 2008
Location: Salt Lake City
Posts: 42
Re: Norcold performance improvement

Quote:
Originally Posted by SheepShagger
That style fan current draw is quite low, but as Jage said forget it's on, and it's still an extra load. Be careful with thermostats, many cheap ones will constantly draw the power needed to run the fan, but when not running the fan will just convert the power into heat. So no gain really except noise.

Couldn't you simply wire it into the existing fridge fan through a switch? That way you can switch it to just come on with the fridge fan, giving it extra cooling, or off all the time (night)?
The problem was that even though the frig manual says that the fan should come on at 90 degrees, I found that mine didn't until it was 120 or more. So tying into the existing fan circuit wasn't an option.

This is basically a summer time issue, so long daylight, good solar recharge (in my case), and even if left on it pulls only 0.08A. You could use a mechanical timer (I believe electronic ones pull their own charge even when off) but then you have the tic, tic, tic issue.

I may still wire in a small LED as an indicator . . .
__________________

__________________
2006 EB 6.0 Diesel, custom gaucho,
Espar hydronic and heat, 2 Solara panels,
Trojan F&R, ARB lockers, Warn winch.
BACKRDS is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 08:53 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×