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  1. #1
    Can any body explain the reason carrier grounds 24 volt
    common leg to frame while most other manufactures do not,
    what purpose does it serve???

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,743
    lennox has been doing this for years. not sure why probably for ignition controls.

  3. #3
    Join Date
    Oct 2005
    Location
    Fairfax, VA
    Posts
    111
    The purpose of having a low voltage system is safety for the operators, and grounding one leg ensures that it stays less than 30 v. Without the tie-down, the voltage can float around with respect to ground. In other words, you can measure 24v from line to line, and still have 50v to ground (called a bias voltage in electronics).

  4. #4
    Join Date
    Apr 2004
    Posts
    7,680
    Most do, sometimes it's not as apparent though. Sometimes its just a trace on the board that connects to one of the mounting screws.

  5. #5
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,944
    It's needed for the new flame sensors and ignition boards to function. The board sends a milivolt charge to the flame sensor which must travel through the flame to ground which then goes back to the board to complete the circuit telling the board that there is indeed a flame.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


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