Results 1 to 9 of 9

Thread: LEV'S and EEV's

  1. #1
    Join Date
    Mar 2006
    Location
    Lancashire
    Posts
    1,876
    Rep Power
    28

    LEV'S and EEV's



    What is the difference between an LEV and an EEV they are both electronic expansion valves aren't they?


    The difference between genius and stupidity is that genius has its limits.

    Marc

  2. #2
    Join Date
    Aug 2003
    Location
    Netherlands
    Age
    49
    Posts
    621
    Rep Power
    21

    Re: LEV'S and EEV's

    LEV = liniear expansion valve
    EEV = electronic expansion valve

    An eev has a curved opening/closing caracter
    an lev, as it's also named, has a linear one.

  3. #3
    Join Date
    Aug 2003
    Location
    Netherlands
    Age
    49
    Posts
    621
    Rep Power
    21

    Re: LEV'S and EEV's

    Perhaps this, quickly made, drawing will help explain it more!
    Attached Files Attached Files

  4. #4
    Join Date
    Oct 2003
    Location
    Belgium
    Age
    62
    Posts
    5,645
    Rep Power
    34

    Re: LEV'S and EEV's

    Sanderh, I wasn't aware that an LEV excisted.
    I saw it in watervalves but never in an expansion valve.
    Can someone give me a practical example of the two?
    What's the benefit of an LEV instead of and EEV?
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  5. #5
    Join Date
    Mar 2007
    Location
    Warwickshire UK
    Posts
    723
    Rep Power
    21

    Re: LEV'S and EEV's

    Most VRV/ VRF systems use LEV valves at indoor units for refrrigerant flow through indoor unit coil.
    The valve has a minature electric motor which turns a set amount each time a low voltage d/c pulse is is sent from the control circuit board to the LEV valve motor coils.The motor is connected to the needle valve by a number of gears like a minature gear box.
    Typically these are made by in Japan by specialist manufacturer call Fujioki. Mitsubishi, Diakin & others all use this manufacturer for supply of LEV valves.
    Anyway the indoor unit is constantly monitoring the refrigerant temperature at inlet & outlet of coil & calculating a type of super heat ratio in cooling mode & sub cool ratio in heating mode. The indoor unit is programed for a target super heat or subcool & so the indoor unit will ramp open or ramp closed the valve to achieve the target SH or SC.
    Typically the valve will gradually ramp more & more open until the target is reached & will then slowly ramp down untill it needs to open again because it is not reaching target SH or SC.
    This type LEV valve has 40 pulse shut possition & 2000 pulse fully open possition. The total open to shut dimension for the needle is about 2mm.
    So when the indoor circuit board sends a command of one low voltage pulse to the LEV valve the needle changes possition by one thousanths of one millimeter.
    Thats one reason why VRV/VRF systems are so good on COP energy efficency,,, very clever elecronic control & very exact refrigerant volume flow control at LEV valve.

  6. #6
    Join Date
    Aug 2003
    Location
    Netherlands
    Age
    49
    Posts
    621
    Rep Power
    21

    Re: LEV'S and EEV's

    The largest benefit of a LEV compared to an eev is that it's linear and doesn't, or at least not one noticeable deviation from input % to valve position. This makes control a lot easier!

  7. #7
    Join Date
    Mar 2006
    Location
    Lancashire
    Posts
    1,876
    Rep Power
    28

    Re: LEV'S and EEV's

    Thanks for the explanation guys...really helpful
    The difference between genius and stupidity is that genius has its limits.

    Marc

  8. #8
    Join Date
    Dec 2007
    Location
    ozzy
    Age
    45
    Posts
    7
    Rep Power
    0

    Re: LEV'S and EEV's

    so is what your saying, an lev is more of a step motor type valve and an eev is an open close type arrangement?

  9. #9
    Join Date
    Nov 2005
    Location
    USA
    Posts
    211
    Rep Power
    19

    Re: LEV'S and EEV's

    IIRC, EEVs use "voice coil" or piezoelectric devices to replace the diaphragm as opposed to a motor. The "voice coil" requires special control to work correctly (force, not position, is proportional to current). I think piezoelectric EEVs are fairly linear but I'm not sure.
    "If Hannah was an air handler, I would be a condensing unit so I could open her TXV and pump my refrigerant through her coils." - a HVAC friend of mine

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •