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FREE ,FREE, NO CHARGE ,Schrader Tee.

to the first 10 tech's that post a picture ,here on the wall, of an installed Schrader T that is installed just before the TXV along with two pressure readings. One press reading will be  from the cond unit and the 2nd press reading will be from the installed Schrader T at the AHU. Send me your address and I will send you a free 3/8 solder type Schrader T . Oh yea, the liquid line has to have at least a 20' vertical rise.

Paul S , you get a Schrader T even if you are #11 or higher.

Comments

  • SpenceSpence Posts: 316Member
    Tee

    Please share your thoughts regarding the purpose of this fitting. Thanks!
  • TechmanTechman Posts: 2,144Member
    edited July 2014
    FREE T

    Simple, so that 10 techs get to see the actual press drop between the cond unit and the TXV. Oh yea, and that press drop gets figured into SubCooling , somehow, doesn't it? And the actual press going into the TXV is used when using a TXV " extended capacity charts" for troubleshooting. Gonna get your  FREE T Spence? Come on! And those 10 techs may tell ten more techs. But then again , I been wrong lots of times!
  • SpenceSpence Posts: 316Member
    edited July 2014
    Sub Cooling

    Put a clamp-on, or other quality thermometer at the TXV and convert the reading to pressure. Subtract that from the pressure at the OD unit to get PD. Simple, easy, and no fitting to create another PD.



    PD in the LL does not figure into a sub cooling calculation.



    You have a big heart to make the offer, though. I like it.
  • Paul S_3Paul S_3 Posts: 1,257Member
    let's say

    I don't have capacity charts, And lineset is long and vertical rise is high how do I use this 1/2"psi rule? Or how do I figure how much subcooling I need thanks Paul s , and I will do the Schrader tee soon
    ASM Mechanical Company
    Located in Staten Island NY
    Servicing all 5 boroughs of NYC.
    347-692-4777
    [email protected]
    ASMHVACNYC.COM
    https://heatinghelp.com/find-a-contractor/detail/asm-mechanical-company
  • meplumbermeplumber Posts: 678Member
    Pressure Drop

    You are wrong in this case Spence.  Pressure drop does indeed figure into the Subcooling calculation when your lift exceeds the 15-20' that the manufacturer factors into their published data.  As we were stating in the adjoining thread, the compressor is just a pump and the refrigerant is a liquid.  No different than in a hydronic system.



    If you don't allow for the pressure drop in high lift situations, you will have a full liquid sight glass at the condenser and a mix at the top of the column.



    Tech, I could have shown you a handful of TXV's with tap tees installed from today's startups, but it is a Federal facility and they get really, really nervous if someone pulls out a camera.  But that is ok, I got a ton of those Schrader tees rolling around in a box in my van.



    Spence, give it a try sometime.  Once you do it, you will see what we are talking about.
  • SpenceSpence Posts: 316Member
    PD

    You're working too hard. Your maker knows how to maintain his desired sub cooling when he publishes limits to length and lift, and what adjustments to make when you're outside the box. Upsized lines and "x" ounces of refrigerant and other measures are for the purpose of maintaining his sub cooling and superheat and the other good things that go with a happy system.
  • TechmanTechman Posts: 2,144Member
    FREE Schrader T and a FREE SGMI

    to you Spence, both FREE ,both get installed @ the AHU. As Meplumber said, there will be a full LL at the cond unit and a mix at the top ,if you are staying at the mfrg's Nameplate SC of 12* for a high lift. Seeing is believing,no,yes!?!?

    The PD sure does get figured into a SC calculation , the PD gets converted into a TEMP drop.
  • TechmanTechman Posts: 2,144Member
    FREE Schrader T and a FREE SGMI

    to you Spence, both FREE ,both get installed @ the AHU. As Meplumber said, there will be a full LL at the cond unit and a mix at the top ,if you are staying at the mfrg's Nameplate SC of 12* for a high lift. Seeing is believing,no,yes!?!?

    The PD sure does get figured into a SC calculation , the PD gets converted into a TEMP drop.
  • TechmanTechman Posts: 2,144Member
    SubCooling Carrier Style

    In Carriers "Handbook of Air Conditioning System Design" there is a formula for figuring SC. On an operating r-12  system.

     100* Cond Temp =116.9psig.

    press at TXV        =87psig  which = 82* Saturation Temp

    SC required         = 100*f  - 82*f  =18f* SC

                                                                                 
  • SpenceSpence Posts: 316Member
    SC

    Sub cooling is, simply, the difference between the operating (saturated) pressure converted to temperature and the actual liquid line temperature measured at the condenser outlet ( LL service valve). This is compared to what the maker has stamped on the nameplate. We try to get as close as possible, yet +/- 3 degrees is almost universally acceptable.



    The last thing that ever should be calculated is the refrigerant charge. System cleanliness, actual air flow, ducts, etc. ALWAYS come before refrigerant diagnosis.
  • TechmanTechman Posts: 2,144Member
    edited July 2014
    FREE

    I agree about measuring the 12* SC at the cond unit, and using the Saturated Temp and then mathing out the #'s to check for the nameplate SC#'s.But what about systems that require a higher SC? You don't leave  a boiler PRV at the factory set point of 12# (SC) for a 1 story house as compared to a 4 story house . So KindaSorta the same applies to the SC, always has!



    I always, usually, most times diagnose the refrigerant system 1st. My gauges will tell me if there is a problem somewhere inside the house , then i'll go over that other stuff . 6 of one, half a dozen of the other.

    Come on Spence ,send in a picture

    Carrier having/using that SubCooling formula doesn't mean a thing?
  • SpenceSpence Posts: 316Member
    More Free

    There is no formula for sub cooling. Again, it is the difference between condensing pressure converted to temperature and the actual liquid line temperature. If you have 6 and the maker wants 10, you have an issue to resolve. If the maker wants 9 and you have 11, you're within accepted tolerances. There is no 12 or 1/2 pound this or that. For SUB cooling to be present, the liquid line HAS to be colder than the saturated temperature. And you should always check superheat too. Sub cooling is not solely a means to an end.



    The never check refrigerant first was not for you, because you are intelligent and you care. I shake when I see someone carrying refrigerant up the driveway when they have not even been in the house. Yikes!
  • TechmanTechman Posts: 2,144Member
    edited July 2014
    NO CHART?FORMULA? for SC?

    Read this and tell me again!
  • TechmanTechman Posts: 2,144Member
    No FORMULA

    Hows this.
  • TechmanTechman Posts: 2,144Member
    edited July 2014
    No formula

    how is this? I guess this is a figment of my imagination. Come on ,now your reaching for straws .
  • SpenceSpence Posts: 316Member
    Formula

    How cool! A Carrier manual from 1961. Love it!
  • TechmanTechman Posts: 2,144Member
    Old Stuff

    How old is Charles's Law and Boyles and Watts . Those Laws still apply. Are you a believer now? Or does my 1965 Carrier book need an update. You can still get your FREE Schrader and SGMI , are you ready?
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