Results 1 to 12 of 12
  1. #1

    Hard--shutoff TXV

    Hard--shutoff TXV what is it??
    Don't interrupt me while i'm talking to myself

  2. #2
    Join Date
    Jul 2005
    Location
    south
    Posts
    590
    a regular txv has a bleed port to allow pressures to equalize when the compressor is off. A hard shut off txv has no bleed port and the pressures do not equalize whe the compressor is off.

  3. #3
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear Gerryboy00,

    Regarding your posted question:

    “Hard--shutoff TXV what is it??”

    It a normal thermal expansion valve, that when the compressor shuts off, the valve port closes 100%. This valve is used to control refrigerant migration among other things, and when using on a single phase compressor system should also be equipped with a hard start kit to aid the compressor based on the increased starting load these valves put on the compressor.

    Respectfully Submitted,
    John J. Dalton CM
    Last edited by john dalton; 04-23-2007 at 05:41 PM.

  4. #4
    Join Date
    Apr 2007
    Location
    Philadelphia
    Posts
    2,192
    Quote Originally Posted by john dalton View Post
    Dear Gerryboy00,

    Regarding your posted question:

    “Hard--shutoff TXV what is it??”

    It a normal thermal expansion valve, that when the compressor shuts off, the valve port closes 100%. This valve is use to control refrigerant migration, among other things, and when using on a single phase compressor system should also be equipped with a hard start kit to aid the compressor based on the increased starting load these valves put on the compressor.

    Respectfully Submitted,
    John J. Dalton CM

    john..i know i seen hard hard shutoff txv..dont the pressures eventually equalize???and i think,not positive,i was told by a carrier rep once years ago to add a time delay and he did not recommend a hard start kit..he said the time delay allows the pressure to equalize,which they would do eventually,and then the compressor would start normally..but your saying they close 100%????

  5. #5
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear D_griff,

    Regarding your previously posted comment and questions:

    “john..i know i seen hard hard shutoff txv..dont the pressures eventually equalize???...”

    Few things in life are 100%, when these types of TXVs close, and the refrigeration system in not operating, the discharge and suction sides will eventually obtain equalized pressures based on “slight leaks” through both the TXV valve port itself, and the suction/discharge valves of the compressor.

    This will take some time, more than a few minutes, and remember, although the pressures are equalized, the rate of refrigerant entering the low side will still be extremely small based on the closed port of the TXV.


    “…and i think,not positive,i was told by a carrier rep once years ago to add a time delay…”

    Adding an anti-short cycling device is always a good idea with almost any refrigeration system that does not have one incorporated in the system’s control circuits, or thermostat, but………these devices are usually setup for no more than five(5) minutes, and most times that is NOT enough time for the system to equalize its pressures.


    “…and he did not recommend a hard start kit..he said the time delay allows the pressure to equalize,which they would do eventually,and then the compressor would start normally..but your saying they close 100%????”

    Although given enough time the suction and discharge pressures will equalize, a relatively warm day will require the compressor to cycle at a rate “faster” than the system has the ability to without a hard start kit of some time.

    Respectfully Submitted,
    John J. Dalton CM

  6. #6
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear D_griff,

    Regarding your previously posted comment and:

    “…and i think,not positive,i was told by a carrier rep once years ago to add a time delay and he did not recommend a hard start kit.”

    If you check out Page 5, under “Accessory Description and Usage, #2 Compressor Start Assistant, you’ll find the words:

    Required for reciprocating compressors in the following applications:

    “Hard shut off expansion valve on indoor coil

    http://www.xpedio.carrier.com/idc/gr...f?SMSESSION=NO

    Notice the manufacturer….Carrier. Most equipment manufacturers highly recommend that hard start kits be put on systems with hard shut off TXVs.

    Respectfully Submitted,
    John J. Dalton CM

  7. #7
    never heard of it .......first time today.

    thanks guys





    BTW happy birthday dear John
    Don't interrupt me while i'm talking to myself

  8. #8
    Join Date
    Apr 2007
    Location
    Philadelphia
    Posts
    2,192
    Quote Originally Posted by john dalton View Post
    Dear D_griff,

    Regarding your previously posted comment and:

    “…and i think,not positive,i was told by a carrier rep once years ago to add a time delay and he did not recommend a hard start kit.”

    If you check out Page 5, under “Accessory Description and Usage, #2 Compressor Start Assistant, you’ll find the words:

    Required for reciprocating compressors in the following applications:

    “Hard shut off expansion valve on indoor coil

    http://www.xpedio.carrier.com/idc/gr...f?SMSESSION=NO

    Notice the manufacturer….Carrier. Most equipment manufacturers highly recommend that hard start kits be put on systems with hard shut off TXVs.

    Respectfully Submitted,
    John J. Dalton CM

    thank you sir..thats why i asked.appreciated as always

  9. #9
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear D_griff,

    I always love it when someone calls me on one of my posts, or comments. Its then that either I have to back it up with previously written material from a textbook, manufacturer’s publication, or news article, or I discover “holes in my HVAC/R knowledge. Either way, I win………..I either confirm what I already know, or I learn something new about my craft…..the ultimate win/win situation.

    Thank you for making me dig friend……………….

    Respectfully Submitted,
    John J. Dalton CM

  10. #10
    Join Date
    Apr 2007
    Location
    Philadelphia
    Posts
    2,192
    Quote Originally Posted by john dalton View Post
    Dear D_griff,

    I always love it when someone calls me on one of my posts, or comments. Its then that either I have to back it up with previously written material from a textbook, manufacturer’s publication, or news article, or I discover “holes in my HVAC/R knowledge. Either way, I win………..I either confirm what I already know, or I learn something new about my craft…..the ultimate win/win situation.

    Thank you for making me dig friend……………….

    Respectfully Submitted,
    John J. Dalton CM
    yeah see im doing it for your own good
    no really dont take it as calling you out,i posted for the same reason,i wanted to know the real deal...

  11. #11
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear D_griff

    I know what you mean…..I often ask additional questions when someone posts something new to me or something that just doesn’t sound right at times. As my old college professor use to always say:

    “Believe nothing you hear and only half of what you see”.

    Respectfully Submitted,
    John J. Dalton CM

  12. #12
    Join Date
    May 2004
    Location
    Los Angeles, CA
    Posts
    1,560
    Dear D_griff

    I guess you could say someone is “calling someone’s hand” upon the subject discussed and wants to see for themselves what you are holding (in the way of HVAC/R knowledge).

    Respectfully Submitted,
    John J. Dalton CM

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