Photo Eye?

stmar Posted By stmar, Dec 6, 2017 at 1:52 PM

  1. stmar

    stmar
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    My Whitfield Profile 30 is about 20 years old. It seems to be working okay but it takes a few tries to start, going into default sometimes. I know the photo eye controls when the pellets feed. Could the photo eye be going bad or do they either work or not work? I cleaned it when I did my annual clean. The wind has been blowing quite a bit lately so that may have something to do with it starting but wanted to cover all bases.
     
  2. bob bare

    bob bare
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  3. stmar

    stmar
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    Thanks for that option, does not look that hard. Any ideas about where to get a ceramic snap switch, most of the ones I see are plastic and higher degree.
     
  4. bob bare

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  5. stmar

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    • Found this one on Ebay, less than $19 includes shipping. Is this correct and a decent price?


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    Have one to sell? Sell now
    Details about CERAMIC F140 Low Limit Snap Disc Switch Stove Blower Fan Proof of Fire +Hardware
     
  6. stmar

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  7. bob bare

    bob bare
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    I have never done the swap,not gonna research it,but will tell you a ceramic one will last much longer,but cost more,and there is a lot of cheap china crap out there.The ebay one looks fine,is ceramic
     
  8. stmar

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    Thanks for your help, not sure if I will do it but nice to have options. I am hoping it is the wind we are having, have had it go through cycles to start before but just seems to be hard starting the last few days. Got it going after several restarts just now, worked perfectly early morning so intermittent.
     
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  9. ericofmaine

    ericofmaine
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    I got the one from Grainger, worked fine for the 4 years I had it in there until I sold the stove this fall.

    Eric
     
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  10. stmar

    stmar
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    Just curious about how this photo eye works. When light is applied does the circuit open or close?
     
  11. Ssyko

    Ssyko
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    An optical sensor converts light into electronic signals. It measures the physical quantity of light and then translates it into a form that is readable by an instrument or another sensor circuit.
     
  12. bob bare

    bob bare
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    On your stove,when it "sees" fire,it closes a circuit,same as a snap switch/thermostat,but is usually low voltage,which is why a snap thermostat can do the same job.
     
  13. Stovensen

    Stovensen
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    No, the one in your link is an "open on rise" snap switch ( some sort of high limit snap switch ).

    A low limit switch is a "close on rise" snap switch.

    The temperature specs for the low limit switch on a typical Whitfield/Lennox stove:
    The switch closes when the temperature exceeds 140 degree Fahrenheit. Opens again when the temperature drops below 120 degree Fahrenheit.

    Replacing the photo-eye with a traditional low limit switch as suggested in Don2222's thread, is a brilliant mod to avoid the annoying stove shut downs when the eye gets dirty.
    Luckily the photo-eye and the low limit switch have the same logical sequence in ohmic change when exposed to flames ( heat ), so they will both serve as "flame watches". The low limit switch is even more well defined in that it switches between infinite Ohms and zero Ohm.

    The ohmic change in a photo cell is lesser defined than in a traditional low limit switch:
    light_cdscovered.jpg light_cdslitmm.jpg
     
  14. stmar

    stmar
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    Thanks, that makes sense, appreciate all the input/info, learn something new every day.
     
  15. stmar

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    Do any of you know if you need a 1/2" or 3/4"? Looks like it comes in both sizes.
    Thanks.
     
  16. Stovensen

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  17. stmar

    stmar
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    Thanks, I appreciate that, seems like every time I think I have it figured out something else pops up. On the bright side my stove seems to be operating properly, I swear the wind had something to do with it. I think I will do the mod though, seems like a good idea because if it is the wind it will be an issue again because we get a lot of wind.
     
  18. stmar

    stmar
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    Ceramic snap switch on the way to me. Checked the wiring and found the wire from the original photo eye, I did the upgrade years ago and repositioned the eye. Looks like I can use the original wire, it even has connectors that I can match to a short piece of wire to the switch. Easier than I had thought.
     
  19. Stovensen

    Stovensen
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    Don2222's thread ( link above ) is very thorough and with detailed pics of the whole operation. As we can see on one of Don's pictures, the combustionblower housing even has the hole prepared for the ceramic low limit switch. Probably the same housing as was used on the old Whitfields.
     
  20. stmar

    stmar
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    It does have the hole in the housing so it should be an easy install. Famous last words, lol.
     

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