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Post a reply to the thread: Should a TXV be open or closed when not in oporation?

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Topic Review (Newest First)

  • 09-03-2019, 08:47 AM
    Poodle Head Mikey
    Embraced.

    Quote Originally Posted by VTP99 View Post
    Jinxed
  • 09-03-2019, 08:44 AM
    VTP99
    Jinxed
  • 09-03-2019, 08:38 AM
    Poodle Head Mikey
    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.
  • 09-02-2019, 11:46 AM
    Olivero
    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.
  • 09-02-2019, 11:02 AM
    Gleng
    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.
  • 09-02-2019, 09:55 AM
    Olivero
    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.
  • 09-02-2019, 09:29 AM
    Gleng
    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!!!
  • 09-02-2019, 09:25 AM
    Poodle Head Mikey
    Open

    Quote Originally Posted by CLMorse View Post
    ?
  • 09-02-2019, 09:20 AM
    Gleng
    Thanks,I didn't know that!!! the power head is bad.
  • 09-02-2019, 09:17 AM
    Gleng
    Hey Olivero , Happy labor day.Glad you're not on the east coast of florida,In the path of the storm!!
  • 09-02-2019, 09:13 AM
    Gleng
    You are getting old!!!I'm right there with you!!!!
  • 09-02-2019, 09:09 AM
    Gleng
    Good reason to Insulate the suction line and TEV properly, and secure the TEV bulb properly to the suction line.
  • 09-02-2019, 02:43 AM
    danielthechskid
    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.
  • 09-01-2019, 08:28 PM
    BBeerme
    Used to be the power heads for A/C would close at 100 psig, and for refrigeration, at 35 psig. Memory might be messed up. Back then there were only three refrigerants, LOL. Probably a greater variety these days.


    Quote Originally Posted by Olivero View Post
    Really? Huh, I didn't know that.
  • 09-01-2019, 08:24 PM
    Olivero
    Really? Huh, I didn't know that.
  • 09-01-2019, 08:22 PM
    BBeerme
    Not always. I think the MOP TEV power head's use a cross charge to close the TEV to make it easier for the compressor to start.


    Quote Originally Posted by Olivero View Post
    If the system is not in operation, the TXV will be open as the bulb the TXV uses to sense temperature will be warm so it will open further to add more refrigerant.

    Unless the TXV is broken, in which case it could be closed.
  • 09-01-2019, 08:18 PM
    Olivero
    If the system is not in operation, the TXV will be open as the bulb the TXV uses to sense temperature will be warm so it will open further to add more refrigerant.

    Unless the TXV is broken, in which case it could be closed.
  • 09-01-2019, 07:59 PM
    BBeerme
    The answer to your question is . . .

    Yes.


    Quote Originally Posted by CLMorse View Post
    ?
  • 09-01-2019, 07:53 PM
    pecmsg
    Quote Originally Posted by Snapperhead View Post
    that depends if they strapped the bulb to it .... or if the bulb is still waiting to be mounted in place
    Not when it’s strapped to the liquid line.
  • 09-01-2019, 07:49 PM
    Snapperhead
    Quote Originally Posted by pecmsg View Post
    What happens as the suction line warms ?
    that depends if they strapped the bulb to it .... or if the bulb is still waiting to be mounted in place
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