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  1. #1
    Join Date
    Oct 2002
    Location
    Lexington, NC
    Posts
    5,137

    Sporlan TEV Adjustment

    I installed a Sporlan TEV today that was adjustable. This particular installation was for an A/C unit, but being most Residential A/C TEVs are not adjustable, I thought it a waste of time to ask the following questions.
    My first question is how do you know when a replaceable power head has failed versus a failure in the other components of the TEV, or in other words when do you know for sure that the powerhead is the issue.

    My second question is: Sporlan shows in their paperwork that in order to adjust you turn one way for up and one for down, but they don't tell how many turns or fraction of a turn = one degree.

    Did I say two? I meant 3 questions. They also showed that they don't allow a Vertical bulb placement. I see vertical placement all of the time and this particular install had no horizontal placement option and the bulb had to be placed after the equalizer tube. Valve held 15 degrees superheat at the coil out of the box even with this misapplication. What was supposed to happen that they don't want a vertical placement and bulb after the equalizer tube?
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  2. #2
    Join Date
    Apr 2010
    Location
    San Diego, CA
    Posts
    197
    My first question is how do you know when a replaceable power head has failed versus a failure in the other components of the TEV, or in other words when do you know for sure that the powerhead is the issue.
    You find a valve all closed up, throw on a new power head and then see if it's fixed. It's usually obvious that the power head has rusted through or something along those lines.

    Sporlan shows in their paperwork that in order to adjust you turn one way for up and one for down, but they don't tell how many turns or fraction of a turn = one degree.
    That's not a question. You're disqualified. (When you're setting it, you turn it a bit and then wait and see where your SH settles out, then you have a slight idea how much further to turn...)

    What was supposed to happen that they don't want a vertical placement and bulb after the equalizer tube?
    Same thing that's supposed to happen when a TEV doesn't have a full column of liquid. Something is going to die a premature death in your system. (Actually it just won't control superheat perfectly. OH NOES!)

  3. #3
    Join Date
    Oct 2002
    Location
    Lexington, NC
    Posts
    5,137
    It could take all day to adjust something like that.
    On the vertical part, I don't understand why a vertical line would matter. I can understand not mounting at 6:00 on horizontal for oil, but on Vertical it would seem that it wouldn't matter as much as the oil should be even spread around the pipe. It isn't like it just rides on the bottom of a horizontal line.
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  4. #4
    Join Date
    Sep 2002
    Posts
    12,195
    The fall back plan-B to the "horizontal only!" mounting directions are: if there is no option to mounting vertical - then the cap tube has to be at the bottom of the sensing bulb when it's mounted.

    I mount all TXV bulbs on vertical suction lines whenever I possibly can. I think they sense better that way and it also serves as my personal version of running with a pencil. <g>

    PHM
    ------




    Quote Originally Posted by nchvac View Post
    I installed a Sporlan TEV today that was adjustable. This particular installation was for an A/C unit, but being most Residential A/C TEVs are not adjustable, I thought it a waste of time to ask the following questions.
    My first question is how do you know when a replaceable power head has failed versus a failure in the other components of the TEV, or in other words when do you know for sure that the powerhead is the issue.

    My second question is: Sporlan shows in their paperwork that in order to adjust you turn one way for up and one for down, but they don't tell how many turns or fraction of a turn = one degree.

    Did I say two? I meant 3 questions. They also showed that they don't allow a Vertical bulb placement. I see vertical placement all of the time and this particular install had no horizontal placement option and the bulb had to be placed after the equalizer tube. Valve held 15 degrees superheat at the coil out of the box even with this misapplication. What was supposed to happen that they don't want a vertical placement and bulb after the equalizer tube?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #5
    Join Date
    Sep 2002
    Posts
    12,195
    How do you know a powerhead is bad?

    Ever had a TXV apart? If not take one apart and see what there is in there. It ain't much and none of it is mysterious. Think about what the powerhead does - it provides the only force to open the valve. Everything else wants to close it.

    Running system - if you hold the bulb in your hand and the suction line in your other hand the powerhead should open the valve and the suction temperature should fall. If not - the powerhead may be bad. If you Know that there is 100 lbs or more of head pressure above the suction pressure AND there is liquid refrigerant to the TXV inlet - then you can be pretty confident that the power head is bad when it fails to respond.

    PHM
    -------




    Quote Originally Posted by nchvac View Post
    I installed a Sporlan TEV today that was adjustable. This particular installation was for an A/C unit, but being most Residential A/C TEVs are not adjustable, I thought it a waste of time to ask the following questions.
    My first question is how do you know when a replaceable power head has failed versus a failure in the other components of the TEV, or in o
    How do you ther words when do you know for sure that the powerhead is the issue.

    My second question is: Sporlan shows in their paperwork that in order to adjust you turn one way for up and one for down, but they don't tell how many turns or fraction of a turn = one degree.

    Did I say two? I meant 3 questions. They also showed that they don't allow a Vertical bulb placement. I see vertical placement all of the time and this particular install had no horizontal placement option and the bulb had to be placed after the equalizer tube. Valve held 15 degrees superheat at the coil out of the box even with this misapplication. What was supposed to happen that they don't want a vertical placement and bulb after the equalizer tube?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  6. #6
    Join Date
    Oct 2002
    Location
    Lexington, NC
    Posts
    5,137
    You lost me a little there Poodle. I thought they want them mounted horizontally. Also, I thought that when we mount a bulb vertically that the cap tube is to come out of the top of the bulb.
    Please clarify.
    I won't feel so bad about vertical mounts anymore if you like them better that way. Probably 2 out of 3 that I see are vertical mount on A/C work.

    And one more thing about the 100 PSI difference. I have noticed, especially in the spring months when low ambients abound, that these high seer units aren't always running at 100 psi over the suction. I haven't posted about it to get the concensus, but I have noted it, especially on hot pull downs. Are we getting to the point of considering that an old rule of thumb?
    Thanks
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  7. #7
    Join Date
    Sep 2002
    Posts
    12,195

    sensing bulb placement thoughts

    Yes: Horizontal is said to be the preferred mounting and not on the bottom of the line.

    My memory for the vertical bulb mounting logic was that they didn't want liquid charge potentially trapped in a cold sensing bulb - so cap tube on the bottom was the rule for vertical mounting. Am I remembering that wrong?

    I don't think it matters-enough-to-measure the difference in sensing resulting from sensing bulb placement. Yes; I agree: probably best not to place them on the bottom of the suction line - but other than that? I think the temps are so damned close everywhere that it makes no difference.

    Why isn't there an equal fuss made about where on the circumference of the suction line we put the thermocouple to SET the superheat? <g>

    I don't think (especially in A/C work!) that there is any oil accumulated on the bottom of any line anyway. They have the design refrigerant velocities so high there is no way it could. <g>
    And if there is: at least on a vertical line it would tend to be an thinner even oil coating all around the inside of the line. <g>

    On low temp, with well designed line sizing, really minimal pressure drops, and possibly sluggish oil return - OK; maybe there might be a difference. But on A/C? I just can't imagine it making any kind of measurable performance difference.

    What do you think? When you picture what is actually going on inside a suction line?

    PHM
    ------



    Quote Originally Posted by nchvac View Post
    You lost me a little there Poodle. I thought they want them mounted horizontally. Also, I thought that when we mount a bulb vertically that the cap tube is to come out of the top of the bulb.
    Please clarify.
    I won't feel so bad about vertical mounts anymore if you like them better that way. Probably 2 out of 3 that I see are vertical mount on A/C work.

    And one more thing about the 100 PSI difference. I have noticed, especially in the spring months when low ambients abound, that these high seer units aren't always running at 100 psi over the suction. I haven't posted about it to get the concensus, but I have noted it, especially on hot pull downs. Are we getting to the point of considering that an old rule of thumb?
    Thanks
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  8. #8
    Join Date
    Sep 2002
    Posts
    12,195

    minimum pressure drop TXV

    The standard performance rating of a TXV was based on, and still is as far as I know, having a minimum of 100 lbs pressure drop across the orifice of the valve. To use less you could special order TXV's for, I think, a 70 lb. drop. Although maybe it was 75 lbs. that was offered.

    Of course the TXV still Works with less pressure drop across it but not as accurately. Now in thinking about it I would think it would make the valve tend to 'hunt'. Opening first too far and then compensating with closing too far.

    Tell me what you know about low PD TXV's. Maybe I'm out-of-touch with the latest-and-greatest. <g>

    PHM
    ------



    Quote Originally Posted by nchvac View Post
    . . . And one more thing about the 100 PSI difference. I have noticed, especially in the spring months when low ambients abound, that these high seer units aren't always running at 100 psi over the suction. I haven't posted about it to get the concensus, but I have noted it, especially on hot pull downs. Are we getting to the point of considering that an old rule of thumb?
    Thanks
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  9. #9
    Join Date
    Sep 2002
    Posts
    12,195

    minimum pressure drop TXV

    The standard performance rating of a TXV was based on, and still is as far as I know, having a minimum of 100 lbs pressure drop across the orifice of the valve. To use less you could special order TXV's for, I think, a 70 lb. drop. Although maybe it was 75 lbs. that was offered.

    Of course the TXV still Works with less pressure drop across it but not as accurately. Now in thinking about it I would think it would make the valve tend to 'hunt'. Opening first too far and then compensating with closing too far.

    Tell me what you know about low PD TXV's. Maybe I'm out-of-touch with the latest-and-greatest. <g>

    PHM
    ------



    Quote Originally Posted by nchvac View Post
    . . . And one more thing about the 100 PSI difference. I have noticed, especially in the spring months when low ambients abound, that these high seer units aren't always running at 100 psi over the suction. I haven't posted about it to get the concensus, but I have noted it, especially on hot pull downs. Are we getting to the point of considering that an old rule of thumb?
    Thanks
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  10. #10
    Join Date
    Jun 2013
    Location
    N. Canada
    Posts
    364
    Wrong on two counts PHM.
    By mounting TXV sensing bulb with cap line down, a so called gas charged txv bulb will lose its liquid via gravity. Any heat added to the bulb will only make super heated vapor (no longer following PT rules).

    Two days ago got a new acct, hospital split ac, compressor bearing washout(?) . SH varying 15 deg in 4 minute swings.
    My daughter managed to get into the crawl space to the AHU. TXV bulb on short vertical run just out of evaporator, followed by hor. run. Moved bulb to hor. run, SH rock-solid with no further changes. Oil trapping, liquid boil off at this point, I'm not sure, but the boys making these valves sure know more than I, so I follow their reccomendations to the letter!

  11. #11
    Join Date
    Sep 2002
    Posts
    12,195

    Thank you very much

    It's always good to knock this stuff around rather than relying on my long ago memories. There is someone on here I think who uses a great tag line. It says something like: It's not what you don't know so much as it is what you Do know that is wrong. <g>

    I may be paraphrasing a little but that's the basic idea of it. And here is just one more example of why it hits close to home for me. <g>

    Thanks!
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  12. #12
    Join Date
    Jun 2013
    Location
    N. Canada
    Posts
    364
    "One is glad to be of service" Bicentennial man

    Now, if some pro in the parallel-hermetic chiller dept would bite on my York YCAL70 problems...

  13. #13
    Join Date
    Sep 2002
    Posts
    12,195

    I still want to disqualify your example though <g>

    Although, in your defense; I looked back and saw that I did leave a word out of what I wrote.

    I wrote: I don't think bulb placement matters much in air conditioning.

    What I meant to write was: I don't think bulb placement matters much in RESIDENTIAL air conditioning. (because of high gas velocities and the rest)

    Of course it is always better to do it exactly 'textbook' - but if you can't, then what? <g>

    That's why I am always trying to get across to people: Do Not Memorize what you do - Always know Why you are doing it; understand the basic nuts & bolts of it. So that when it becomes necessary to innovate - you know what can and cannot be tolerated.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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