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  1. #14
    Join Date
    Jul 2002
    Location
    Chariton, Iowa
    Posts
    559
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    Think about this for a second. The TXV has bulb pressure pushing down on the diaphragm trying to open the valve and equalizer (sensed suction) pressure + spring pressure pushing up trying to close it. The one that is greater wins.

    While operating the spring pressure + the bulb charge refrigerant type sets the superheat. This is why superheat can change as suction pressure changes, refrigerants don't have a fixed pressure change:temperature change ratio.

    When the system shuts off the suction pressure rises but the bulb initially stays the same temp so the same pressure and the valve closes. The coil and bulb then both gradually warm up to the ambient temp around them, if the bulb warms up faster than the coil the valve may open slightly but only just enough to let in refrigerant and bring the equalizer pressure up and close it again. Once both have warmed to the same ambient the bulb and equalizer pressures will be equal and the spring will keep the valve closed.

    On a MOP valve the bulb runs out of liquid and stops rising at a set pressure and that just closes the valve more.

    The exception is a bulb that is in a hotter ambient than the coil, like an externally mounted bulb in a hot attic with the system fan set to on keeping the coil at return wet bulb temp until it dries then dry bulb temp. Unless it is a MOP valve that hot bulb could keep the valve open and let the refrigerant migrate to the evaporator and fill it up just like on a fixed metering coil.

  2. #15
    Join Date
    Oct 2009
    Location
    Atlanta,Ga.
    Posts
    496
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    Good reason to Insulate the suction line and TEV properly, and secure the TEV bulb properly to the suction line.
    Last edited by Gleng; 09-02-2019 at 09:31 AM.

  3. #16
    Join Date
    Oct 2009
    Location
    Atlanta,Ga.
    Posts
    496
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    You are getting old!!!I'm right there with you!!!!

  4. #17
    Join Date
    Oct 2009
    Location
    Atlanta,Ga.
    Posts
    496
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    Hey Olivero , Happy labor day.Glad you're not on the east coast of florida,In the path of the storm!!

  5. #18
    Join Date
    Oct 2009
    Location
    Atlanta,Ga.
    Posts
    496
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    Thanks,I didn't know that!!! the power head is bad.

  6. #19
    Join Date
    Sep 2002
    Posts
    26,277
    Post Likes
    Open

    Quote Originally Posted by CLMorse View Post
    ?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  7. #20
    Join Date
    Oct 2009
    Location
    Atlanta,Ga.
    Posts
    496
    Post Likes
    Do expansion valves work better when they are strapped to the liquid line. Do you mean I have been strapping them to the suction line by mistake all these years!!!

  8. Likes bacciagalupe liked this post
  9. #21
    Join Date
    Oct 2016
    Location
    Clearwater, Florida
    Posts
    1,437
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    Quote Originally Posted by Gleng View Post
    Hey Olivero , Happy labor day.Glad you're not on the east coast of florida,In the path of the storm!!
    To you too buddy.

    Yeah, we're watching it, hopefully it doesn't shift direction.

    I feel sorry for the Bahamas though, man, that's a narly storm.

  10. #22
    Join Date
    Oct 2009
    Location
    Atlanta,Ga.
    Posts
    496
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    Bahamas got nailed bad!!!hopefully the storm stays off the coast far enough to minimize damage.looks like florida will be ok.looks worse for georgia coast and the carolinas.Lets hope it stays far enough off shore.

  11. #23
    Join Date
    Oct 2016
    Location
    Clearwater, Florida
    Posts
    1,437
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    Yeah, they got it really bad.

    Hopefully it just veers off completely, but you never know. We're on the ready though, if it decides to come to Clearwater, we'll be ready for it.

  12. #24
    Join Date
    Sep 2002
    Posts
    26,277
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    You'll be alright.

    For thousands of years Native Americans made their homes, and wintering sites around what is now Tampa Bay. North of Tampa Bay there are many sacred sites, burial grounds, and ceremonial areas. In 1921 a destructive hurricane come ashore near Tarpon Springs (20 miles from Clearwater) and did extensive damage to their sacred sites.

    Soon after that Native Americans from all around the southeastern US came there, performed various rituals, and so cast a protective spell over their area: asking that their sacred sites be spared from any further damage.

    To the best of my knowledge every area in Fl has sustained hurricane damage, and sometimes massive damage, at least once in the last 98 years. All, that is, all except for one. The area blessed by the Native Americans' protective efforts.


    PHM
    -------


    Quote Originally Posted by Olivero View Post
    Yeah, they got it really bad.

    Hopefully it just veers off completely, but you never know. We're on the ready though, if it decides to come to Clearwater, we'll be ready for it.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  13. #25
    Join Date
    Jan 2010
    Posts
    17,317
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    Jinxed

  14. #26
    Join Date
    Sep 2002
    Posts
    26,277
    Post Likes
    Embraced.

    Quote Originally Posted by VTP99 View Post
    Jinxed
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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