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pulpwood007's avatar
pulpwood007
Explorer
Jun 22, 2020

digital temperature controller

I want to add a couple of 140mm fans to the back of my refrigerator to cool the coils. Instead of manually turning the fans on and off I would like to control them with a thermostat.

I found the 2 controllers below, but it looks as if you can only activate the built in relay at a designated high or low temp, but I can't see that a specific temp range can be designated to cycle the fans on and off accordingly.

Hypothetically, I'd like to turn the fans on at 80 degrees and off at 70 degrees. Any suggestions on what to use?

https://www.amazon.com/bayite-Fahrenheit-Digital-Temperature-Controller/dp/B011VGAPOC/ref=sr_1_8?dchild=1&keywords=12vdc+inkbird+programmable+thermostat&qid=1592862705&sr=8-8

https://www.amazon.com/Inkbird-Temperature-Controller-Fahrenheit-Thermostat/dp/B019I3YCFS/ref=sr_1_10?dchild=1&keywords=12vdc+inkbird+programmable+thermostat&qid=1592862751&sr=8-10
  • pulpwood007's avatar
    pulpwood007
    Explorer
    Jun 23, 2020
    DrewE wrote:
    To answer the original question, most of those digital temperature controllers do have the ability to set the temperature differential between their turning on and turning off. The first one linked, for instance, apparently can set that to anywhere between 1 degree and 25 degrees.


    Thanks for all the great suggestions. The instructions for those digital controllers make little sense to me. Also checked Youtube and found vague info. I'm going back and do more research.

    The snap disks may be the most reliable solution. Also, the mechanical switch in these may last longer. Big question now is what temp I need to cycle ON and what temp OFF??

    Another possibility I thought of involves a fan that is already on the fridge. Even though I can't see it because of the tight install, there is a small fan that cycles on and off. It's kinda loud so I assume it's probably a 60 or 80 mm muffin fan. If I can find a relay that controls it, I could come off that for the extra fans.
  • DrewE's avatar
    DrewE
    Explorer II
    Jun 23, 2020
    To answer the original question, most of those digital temperature controllers do have the ability to set the temperature differential between their turning on and turning off. The first one linked, for instance, apparently can set that to anywhere between 1 degree and 25 degrees.
  • time2roll's avatar
    time2roll
    Nomad
    Jun 23, 2020
    +1 for the snap disk. I would strap it to one of the fridge coils that gets hot.

    I use these:

    http://senasys.com/product/2570-34-sealed2570f09



    I selected 3/4" pipe mount, close at 130F open at 115F.
    Go back and select what is best for your situation.
    Home page has some adjustable digital stuff if you really need to monkey with it.
  • Blacklane's avatar
    Blacklane
    Explorer
    Jun 23, 2020
    My Dometic DM2652 refrigerator came from the factory with a small 12V fan and a snap disk temperature switch. I never checked to see what the values were.

    I would also look into one of the many kits available that have the fans, brackets, temperature switches, etc. for a reasonable price. Some are two-stage, multiple fans, etc.

    One source: https://rvcoolingunit.com/Dometic-add-on-Frame-Fan-bracket-kit-2-fans-thermostat-wiring--P3261872.aspx
  • pulpwood007's avatar
    pulpwood007
    Explorer
    Jun 23, 2020
    Can you provide link to a snap disk? I don't know what they are. I'm not interested in over temp applications at this time.

    I'm still interested if the controllers in my OP will work???
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jun 22, 2020
    Perhaps 120-130 on and about 20F less for off. Over temp much higher like in the 180F+ range.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jun 22, 2020
    In Texas the fans will never turn off. :B Use a $10 snap disk for on/off and a much higher one for over temp - approaching fire level.
  • enblethen's avatar
    enblethen
    Nomad
    Jun 22, 2020
    Have you check the installation for proper clearance between the cooling unit and the exterior wall?
    Either unit should work if they have all the components included. They may not like the refer exterior cabinet. Are you planning to mount unit inside which would be better.

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