Forum Discussion

ScottG's avatar
ScottG
Nomad
Jul 21, 2018

Fan for fridge

I am installing an ARP protection system on my Norcold and the unit has built in fan control.
The fridge has an existing little fan mounted in the middle of the back side between the upper and lower coils. I could have the ARP control that fan or I could install a 120mm/5" fan fan under the roof vent!

My question is which will do a better job? Will installing the fan on top be a significant restriction when it's not running?

FWIW, the fridge has no performance issues but then again, I've never been in temps over 100. I also for making things better when ever I can!

Scott
  • Computer fans can be horrid junk doomed to premature failure while consuming lots of juice and making lots of noise, or be highly engineered for extreme reliability, and effective quiet efficient air movement.

    The Noctua NF-f12 is one of the latter. It moves 53CFM for 0.05 amps, and its static pressure rating is about 2x that of other 120mm fans which have the same/similar or higher CFM rating and draw 2 to 3x more amperage.

    The Noctua fans have 6 year warranties and I have one appraoching that age..

    The NF-F12 is very quiet and 0.05 amp draw is one AH consumed every 20 hours. It also comes with inline resistor cable options to run it at even slower speeds and lesser ampdraw.

    The NF-F12 also comes in industrial versions that are IP52 or even higher rated, and one of tham can spin at 3K rpm.

    3K rpm is quite loud, but Noctua also sells a PWM speed controller NA-fc1 that is more or less plug and play, so one can dial in a volume and airflow and acceptable noise level, and on the hottest of days it can move 110CFM for 0.3 amps, making it an incredible performer. It can also be slowed down to very slow and silent via that PWM controller, and to impeller speeds and amp draw well below 0.03amps.

    So don't assume all computer muffin fans are the same. This market for 120MM 12v DC computer fans in incredibly competitive, and the higher end products design and engineering is impressive.

    Another favorite 120mm fan of mine is the dual ball bearing silverstone FM121. This fan comes with a built in speed controller and one can extend the wires and mount the speed control potentiometer well away from the fan. It is also rated for upto 110CFM but only half the static pressure of the Noctua 3k rpm NF-f12, and the SS FM121 also draws 25% more juice to move that much air.

    I've had one in continuous operation for over 7 years now and it sees several hours at 14.7v every day, though I am not sure of the voltage drop on its wiring to my ceiling.

    My personal preference is for powerful fans, on a speed controller, and when their amp draw is neglegible at reduced speeds, I have them run 24/7 and not bother with temperature controlled activation/deactivation.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    I put a Computer type fan in my Fride outside 24x7 run two more inside.The last two really help with defrost issues.
  • Old-Biscuit wrote:
    ScottG wrote:
    Good point about the different temp set point OB.
    I know your familiar with these things; what temp setting would you use for the roof fan?
    They say it's preset to #5 for the sensor to be on the second to bottom tube. Good nuff?


    #5 is same as Norcold OEM.....On/130*F - Off/115*F

    I would test it at the same setting....checking to see IF the ARP controlled fan comes ON at same time as Norcold OEM fan

    Then change ARP Fan setting to coincide with Norcold OEM
    Suspect you will end up on #4/#3 setting so both fans run together


    Thanks again OB.
    You may remember from a post last week that my oem fan quit right after the first weekend we used the RV nearly a year ago.
    I'll be trouble shooting that little issue this coming winter when I pull the fridge in the off-season to tidy up the installation.

    Cheers,
    Scott
  • ScottG wrote:
    Good point about the different temp set point OB.
    I know your familiar with these things; what temp setting would you use for the roof fan?
    They say it's preset to #5 for the sensor to be on the second to bottom tube. Good nuff?


    #5 is same as Norcold OEM.....On/130*F - Off/115*F

    I would test it at the same setting....checking to see IF the ARP controlled fan comes ON at same time as Norcold OEM fan

    Then change ARP Fan setting to coincide with Norcold OEM
    Suspect you will end up on #4/#3 setting so both fans run together
  • joelc wrote:
    I have a 10 cu. single door Norcold. I installed a small muffin fan to the lower area that I turn on in hot weather. I have it raised slightly so air can get uner it and it blows upward. The air flow helps the fridge quite a bit. I hook the 12V to one of the wires on the fridge. I just wish I had a thermal switch. But it works great. You will be very happy with your results. The idea is to cool the fins on the top and to increase air flow.


    The 10 cu/ft is new to me and from my research, it has the same size cooling unit as the 7.5/8.0 cu/ft. Do you ever have any issues with it not keeping up in extremely hot weather?
  • joelc's avatar
    joelc
    Explorer III
    I have a 10 cu. single door Norcold. I installed a small muffin fan to the lower area that I turn on in hot weather. I have it raised slightly so air can get uner it and it blows upward. The air flow helps the fridge quite a bit. I hook the 12V to one of the wires on the fridge. I just wish I had a thermal switch. But it works great. You will be very happy with your results. The idea is to cool the fins on the top and to increase air flow.
  • Good point about the different temp set point OB.
    I know your familiar with these things; what temp setting would you use for the roof fan?
    They say it's preset to #5 for the sensor to be on the second to bottom tube. Good nuff?
  • Fan in roof vent will not be an obstruction........cause you will set it to run based on 'temp sensor'

    OEM Fan thermostat is attached to condenser fin at top of fridge and closes at 130*F --- opens at 115*F (CONDENSER FIN Temp)


    APR Temp sensor is attached to lower absorber tube and on/off temp can be set 90/75 up to 140/125 *F

    Enhanced airflow/draft means more HOT ammonia vapor condensed into liquid (condenser) ....more liquid condensed/more cooling affect.

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