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  1. #1
    Join Date
    Nov 2008
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    Edmonton, Alberta
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    Gas valve with rectifiers

    Had a service call today on a Carrier roof top M#48TMF012---501HQ. Found unit locked out on failed ignition (gas valve would not open with 24V). Replaced valve and checked operation. OK. The new valve (White Rodgers 36H54) was an excact replacement and came with a wiring diagram that showed rectifiers inside the valve. Does anybody know why there would be rectifiers on gas valve? Also when I removed the common wire from the valve when the Carrier control/ignition board was in the heating mode, the board would lock out on internal fault (8 flashes). This is the valve http://www.partsguy.com/pdf/36H64-463%20INS.pdf

  2. #2
    Join Date
    Apr 2006
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    mechanical room
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    1,259
    probably just a vdc valve

  3. #3
    Join Date
    Nov 2006
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    Southeastern Pa
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    Maybe I'm missing something.

    Are you saying you are surprised that there are rectifiers in the gas valve?
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  4. #4
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
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    1,112
    Are these rectifiers how slow-open or step-open functions are achieved?

  5. #5
    Join Date
    Nov 2008
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    Edmonton, Alberta
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    Quote Originally Posted by timebuilder View Post
    Maybe I'm missing something.

    Are you saying you are surprised that there are rectifiers in the gas valve?
    I tried to ohm out the coil but because of the rectifiers, I guess, it showed open on the multimeter. The valve would click and draw amps but would not let gas through. I never knew gas valves had rectifiers.

  6. #6
    Join Date
    Nov 2008
    Location
    Edmonton, Alberta
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    Quote Originally Posted by syndicated View Post
    Are these rectifiers how slow-open or step-open functions are achieved?
    Not sure but I'm just curious what's their purpose

  7. #7
    Join Date
    Oct 2012
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    The Frozen Tundra
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    The rectifier is to convert the 24vac to dc current, and the coil inside the gas valve is dc. They call it an "internally rectified coil".

    I think some water valves in ice machines are the same way.

  8. #8
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
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    Quote Originally Posted by Mike19 View Post
    The rectifier is to convert the 24vac to dc current, and the coil inside the gas valve is dc. They call it an "internally rectified coil".

    I think some water valves in ice machines are the same way.
    I understand the function of a rectifier, I'm just trying to determine its purpose. It seems like for a fast-open valve, there would be no purpose in changing to DC...

  9. #9
    Join Date
    Feb 2010
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    Quote Originally Posted by syndicated View Post
    I understand the function of a rectifier, I'm just trying to determine its purpose. It seems like for a fast-open valve, there would be no purpose in changing to DC...
    DC is better for solenoids. No chatter or buzz and the solenoid lasts longer.

  10. #10
    Join Date
    Oct 2012
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    The Frozen Tundra
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    DC coil has no inrush when it pulls in. I think they run cooler and draw less current too.

  11. #11
    Join Date
    Aug 2012
    Location
    Los Angeles
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    18
    [QUOTE=klubpolo;14901431]Also when I removed the common wire from the valve when the Carrier control/ignition board was in the heating mode, the board would lock out on internal fault (8 flashes). [/URL][/QUOTE

    What is the fault for 8 flashes, should be listed on the cover panel, Do you get 8 Flashes immediately? Or dose the unit try unit fail on ignition consecutive times before the 8 flash lock out?

  12. #12
    Join Date
    Nov 2004
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    up in the hizzy
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    1,384
    [QUOTE=vahe501;14921141]
    Quote Originally Posted by klubpolo View Post
    Also when I removed the common wire from the valve when the Carrier control/ignition board was in the heating mode, the board would lock out on internal fault (8 flashes). [/URL][/QUOTE

    What is the fault for 8 flashes, should be listed on the cover panel, Do you get 8 Flashes immediately? Or dose the unit try unit fail on ignition consecutive times before the 8 flash lock out?
    the 8 flashes means "the board kicked the bucket"

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