Thermal Switch

Discussion in 'OnBoard Electronics & Controls' started by michael pierzga, Mar 4, 2013.

  1. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    Thermal switch.

    A new chart plotter with an ultra bright screen is generating too much heat in the nav station. Im worried that other pieces of electronic gear will be damaged by the waste heat.

    Id like to install a cooling fan with a thermal switch in the nav center cabinet.

    What is the name of this thermal switch ? I assume a computor CPU must have one to start its cooling fan
     
  2. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    thermostat... referigeration wholesalers will sell them... its basically a thermocouple with a relay, thats it...
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Small CPU fans just run, once the computer is fired up. You can use the setup menu on the plotter to reduce the brightness of the screen, which will cut some heat. If it was me, I'd just install a small pancake fan and have it start up as the LCD (or whatever) does.

    [​IMG]

    This is a 3" fan 12 VDC and just a few bucks. It moves about 80 CFM (2.2 CMM).
     
  4. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    I second this. Keep it simple.
     
  5. hoytedow
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    hoytedow Wood Butcher

    Ditto the second.
     
  6. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    ...Ive got a whisper quite dc fan. ..1.5amp 24v... and have constructed the ductwork and fan enclosure. Now I need to turn it on.

    In the RSONLINE cataloque I see a few thermo relays.

    For instance http://uk.rs-online.com/web/p/thermostats/2295935/


    How do the turn a laptop computer CPU cooling fan on ?

    It must be a normally off switch and hopefully something I can glue on the back of the chart plotter.
     
  7. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Ask CDK : http://www.boatdesign.net/forums/profile/cdk.html
     
  8. dzausta
    Joined: Feb 2013
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    dzausta Junior Member

    ok what you can do is get a thermal circuit breaker wich just attaches to the back of the chart plotter and it will turn the fan on if a certain temperature is reached and it turns off on once its under a set temperature, that will save your fan from being constantly on. link bellow

    http://www.jaycar.com.au/productView.asp?ID=ST3821&form=CAT2&SUBCATID=969#1

    Also see if you can utilise a heat sink (installing a fan alone might not do much) as they will cool your equipment a lot better. Have the fan attached to the heat sink. Check out the link bellow will have more explanation on how heat sinks are set up.

    [​IMG]

    http://www.designworldonline.com/rx-for-cooler-medical-devices-heat-exchangers/#_
     
  9. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Then the following product is imo more suitable for the task - a normally open switch which closes the contacts and turns on the fan after the temperature exceeds a preset value: http://www.jaycar.com.au/productView.asp?ID=ST3831&form=CAT2&SUBCATID=969#1

    However, the fan is just a part of the solution, and not necessarily the required one (or the definitive one either). Firstly, you have to understand why does the temperature rise when the plotter screen is turned on. It could be a simple matter of establishing a correct natural convection flow over the electronic board, by creating ventilation inlets and outlets where necessary.

    Without this step, the cooling fan (if it will still be necessary) might actually end up re-circulating the hot air inside the console.
     
  10. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    The problem is the cabinet that the equipment is mounted is.

    It needs a forced air supply to dissipate the heat produced by the new sunlight readable 1000 NIT screen plotter. 1000 nit is about five times brighter than a normal screen. An Ipad is about 200nit I think

    That temp switch is manufactured by Honeywell. I ordered two today. Hopefully it works with low volt dc power.

    Ventilation is needed 24 hours per day in summer operation.
     
  11. Submarine Tom

    Submarine Tom Previous Member

    Honeywell has an info line.

    I suggest you call it.

    Don't hang up until you get your answer.

    You'll get a call centre in India but they'll put you on hold while they call USA for the answer.

    I wouldn't bother with the switch.

    You don't need it.

    On/off with the power switch as recommended earlier.
     
  12. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The modern CPU fan is controlled by firmware, a sensing junction within the CPU and a FET amplifier stage on the main board. You want none of these in your cabinet!

    But there is a very simple, reliable 50 cents thermostat called Klixon. It has the size of a coin, two 6.3 mm terminals and is available both NO and NC for a wide range of temperatures, starting at 40 C.
     
  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I think a switch is an unnecessary complication, as the moment you fire up the plotter, you're going to start having heat issues. A heat sink is a good idea and will improve heat removal efficiency.
     
  14. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Once again, I second this opinion. :)
     
    1 person likes this.

  15. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    Once again, I ditto the second. :D
     
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