Results 1 to 5 of 5
  1. #1
    Join Date
    Mar 2007
    Posts
    61

    19XL Evap Refrig Temp

    Can your guys please explain me why the PSIO of Carrier 19XL5353304CR with R134A S/N 1994Jxxxxx chiller converts Evap Refrig Pressure 33.7 psig to 40 f Evap Refrig Temp? The sat. temp of R134A at 33.7 psig is 38.59 f?

    The evap. pressure transducer has been calibrated at 0 psig and 250 psig per IOM.

    Is it a problem with PSIO?

    What is the guide vane travel limit for this model to set in SERVICE3 screen under EQUIPMENT SERVICE menu?

  2. #2
    Join Date
    May 2001
    Location
    Western Wa
    Posts
    1,834

    Evap temp sensor?

    I can't remember if XL's have one but the XRV's I take care of all have one.

    The vane opening is limited to match the job specs. Watch current if you mess with it.
    God Bless our Veterans

    God Bless the USA

  3. #3
    Join Date
    Oct 2004
    Posts
    115
    Make sure the machine is off when you look at the pressure and the evap refrigerant temp. If the temperature is not corresponding to the pressure, then you did not calibrate the pressure transducer correctly. (probably at the high pressure setting).

    A new PSIO would get you back to the standard calibration and get you back to normal pressure-Temp curve, but that's an expensive proposal.

    The max guide vane opening should generally be set for 80% for 134a. Don't ever set this value higher. (80% equates to a 90 degree change in the guide vane opening. 90 degrees guide vane is wide open, beyond that is closing again.

    Sometimes (rarely on134a, lots with R22 units) due to the building operation, the machine will be at max load at small guide vane angles or percents. Its then that you want to limit the travel of the guide vanes so that the unit can't go so far open that it takes forever to unload. That is when this setting is set lower than 80%. (R22 units the default opening is 50%.)
    Tight is tight, Too tight is broke.

  4. #4
    Join Date
    Mar 2007
    Posts
    61
    Quote Originally Posted by techtalker View Post
    Make sure the machine is off when you look at the pressure and the evap refrigerant temp. If the temperature is not corresponding to the pressure, then you did not calibrate the pressure transducer correctly. (probably at the high pressure setting).

    A new PSIO would get you back to the standard calibration and get you back to normal pressure-Temp curve, but that's an expensive proposal.

    The max guide vane opening should generally be set for 80% for 134a. Don't ever set this value higher. (80% equates to a 90 degree change in the guide vane opening. 90 degrees guide vane is wide open, beyond that is closing again.

    Sometimes (rarely on134a, lots with R22 units) due to the building operation, the machine will be at max load at small guide vane angles or percents. Its then that you want to limit the travel of the guide vanes so that the unit can't go so far open that it takes forever to unload. That is when this setting is set lower than 80%. (R22 units the default opening is 50%.)
    Thank you, Techtalker.

    We did calibrate all transducers (Evap, Oil, Cond) at 0 PSIG and 250 PSIG per IOM. While the chiller is running, we get 40 f Evap. Refrig Temp at 33.7 psig instead of 38.59 f at Pressure Temp curve. Why not be on the pressure temp curve? Will it be any problems with the chiller?

  5. #5
    Join Date
    Oct 2004
    Posts
    115
    I don't see it as a big issue. You are less than 1.5 degrees high. The controls limit the machine before the temp hits 33 F anyway. Just be aware of this when you are looking at approach temperatures. ( I always use the temps on the PIC as a guide, when I want accuracy, I get out the guages)Those PIC I modules are becoming rare. They no longer make the computer chips that run the software and the price to get a new PSIO is going to only increase.
    Tight is tight, Too tight is broke.

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