Results 1 to 5 of 5

Thread: txv

  1. #1
    Join Date
    Feb 2005
    Posts
    7
    Could someone help me explain the difference between none-bleeding expansion valve and bleeding expansion valve and how are they connected differently?

    Thanks

  2. #2
    A none bleed expansion valve is a valve that will close completely, not to allowing the systems pressures to equalize. This helps prevent flooding the evaporator on the off cycle.

    A bleeding expansion valve does allow pressure equalization on the off cycle, were evaporator flooding is not a problem, and allows for a lower torque compressor for starting.

    Both valves would be connected the same. Only the internal parts are differant.

    These designs are for differant system applications. Changing valves on a system could cause the compressor to slug liquid, or a compressor starting problem.

    Why do you ask?

  3. #3
    Join Date
    Feb 2005
    Posts
    7
    thanks,

    I often got asked and don't know

  4. #4
    Some non bleed applicatins will use the TXV as a solenoid because it will provide 100% shut off and in place of using a large solenoid, You can use a small one on the externally equalizer line to act as a pilot duty solenoid and slam the valve shut.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,324
    A non-bleed valve will do as the others say; i.e. not allow system equalization to prevent floodback to the compressor upon system startup.

    It is also thought that a system that does not equalize after shutdown will spend less time coming back into its nominal operating parameters after it restarts. IOW the compressor isn't spending a lot of time pulling the evap back down to design saturated vapor temp/pressure since the pressure in the evap at startup is more or less already there.

    Non-bleed TXV's will require a start cap and potential relay on a single phase compressor.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event