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  1. #1
    Join Date
    Feb 2012
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    How does this switch ever work?


    The autopilot switch images below came out of a Regency Gas Fireplace. The pilot flame could not stay on so I took this part of the fireplace. It is a White Rodgers Autopilot model 3056-2. The first photo shows a partially disassembled switch. I think the "nail looking thing" at the end of the copper wire is a thermalcouple. The copper wire is soldered/welded to a rigid copper dome/hat. The second photo shows the switch completely disassembled. The copper hat sit on top of a plunger. The plunger is made of two parts, the part that came into contact with the copper dome is made out of plastic. The bottom of the plunder is made out of copper.

    For the switch to work, the plunger has to be depressed down, overcoming the force of the coil spring and another spring, to connect the two bladed terminals together.

    I don't see any thing that can take the current from the thermalcouple to induce a force on the plunger to push it down.

    Please explain the mechanism in which the thermalcouple could force the plunger down to complete the circuit.

    Thank you very much!

    Please click on these links if images do not show up. THanks.

  2. #2
    Join Date
    Jan 2006
    Powell River, BC, Canada
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    Quote Originally Posted by fire-parts View Post
    That is a mercury switch. They are not field serviceable and no longer available.
    Bingo. The bulb that sits in the pilot flame contains mercury and the pressure created by heat from the pilot is what closes the switch. They are no longer available as when they fail they release toxic mercury. As far as I know they haven't come up with a replacement for them yet.
    Where are you? Are you done yet? I got ONE more call for you.....

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