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Thread: Trane RTAA

  1. #1
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    Angry Trane RTAA

    Am I the only one who shakes my head when I have to pull a sensor to check accuracy? Why doesn't Trane use wells for the sensors?

  2. #2
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    Quote Originally Posted by seathop View Post
    Am I the only one who shakes my head when I have to pull a sensor to check accuracy? Why doesn't Trane use wells for the sensors?
    I service quite a few RTAAs and RTWAs.

    I want to pull my hair out every time I have to check or change a sensor.

    I have taken more "Trane oil baths" than I can count.

  3. #3
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    Am I the only one who shakes my head when I have to pull a sensor to check accuracy? Why doesn't Trane use wells for the sensors?


    Thats what that fancy chart in the IOM is for , you know the one that compares resistance to temperature ??????????
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage and yes it still gives me goosebumps
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    In the new big shop , greasin', oilin' . tweakin' n shinin' !!

  4. #4
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    Thread Starter
    Reading the fancy chart is easy, how do you get an accurate temp. reading of the sensor, especially if its submerged in glycol in the chiller barrel or inside the suction line ect. sensors whos inputs dictate chiller operation must be accurate, thats why they recommend changing them in pairs!! To compare two sensors that are in two different locations, I don't know a better way to do it but to remove them to see if they read the same ambient air temp. What am I missing?
    Last edited by seathop; 12-19-2010 at 07:15 PM. Reason: Additional information

  5. #5
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    In the 14yrs that I have been working on the RTAA I have never seen a sensor off by a small amount . They are always way off , like out to lunch off , because the sensor has either shorted , grounded or is open . if you have a good infared or strap on sensor themometer or if its a refrigerant sensor use your gauges and work it backwards you shouldnt need to pull the sensor other than to replace it .
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage and yes it still gives me goosebumps
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    In the new big shop , greasin', oilin' . tweakin' n shinin' !!

  6. #6
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    Quote Originally Posted by graham View Post
    In the 14yrs that I have been working on the RTAA I have never seen a sensor off by a small amount . They are always way off , like out to lunch off , because the sensor has either shorted , grounded or is open . if you have a good infared or strap on sensor themometer or if its a refrigerant sensor use your gauges and work it backwards you shouldnt need to pull the sensor other than to replace it .
    Same here, never seen one off by a little, alway's way outa range. I have also never had an issue changing one. Pull it down to 2-3psig and good to go. I only had an issue with 1 water side sensor that the water valves were so rotted out they did not work. I took a bath on that for sure.

  7. #7
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    Trane RTAA

    Thermistor sensors such as Trane use in RTAA's can go out of range, especially the ones that are in cold spots such as leaving CHW: they suck in moisture sometimes which reduces the resitance and increases the temperature reading. I have only spent about six years on these things but agree with Graham: you shouldn't need to pull them out. You have two circuits: compare them. If your leaving chilled water is out you'll see that when you compare it to ent. CHW; you'll also likely get diags coming up telling you so. The RTAA is a great machine: don't knock them!

  8. #8
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    RTAA is a good machine, I agree with above that they are usually way off if they are off at all and you shouldn't need to pull the sensors to check them.

  9. #9
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    I have maybe changed a dozen in 18 years at Trane.

  10. #10
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    Sensor errors

    I've also been heavily involved with RTAA.RTHA,RTHB and RTWA sensors and if they are way off it is easy to detect by using the charts. You may also have the alarm status letting you know whats going on with the temperature sensor. As a procedure during annuals if the sensor accuracy looks questionable (entering water a few degrees cooler then my thermometer comes out) the resistance of the sensor is checked. Another major problem I have come across is when a sensor (pair) has been changed the new cables are cut and then wire nutted to the existing terminations. I prefer to use the entire new sensor and remove the all the old wire along with the sensor, route the new cable as I'm removing the old and make a new termination in the amp plug on the control board. It really isn't that hard to do.-GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  11. #11
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    Another major problem I have come across is when a sensor (pair) has been changed the new cables are cut and then wire nutted to the existing terminations. I prefer to use the entire new sensor and remove the all the old wire along with the sensor, route the new cable as I'm removing the old and make a new termination in the amp plug on the control board. It really isn't that hard to do.-GEO


    Thats the way its supposed to be done but there are a lot of hacks and lazy @&?holes out there that think they know better !!!!!!!!!!!!!!!!!!
    And its guys like us that do it right that have to fix their #@?$ work !!!!!
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage and yes it still gives me goosebumps
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    In the new big shop , greasin', oilin' . tweakin' n shinin' !!

  12. #12
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    Quote Originally Posted by ga1279 View Post
    ...As a procedure during annuals if the sensor accuracy looks questionable (entering water a few degrees cooler then my thermometer comes out) the resistance of the sensor is checked...
    i, too, used to check the resistance on suspect sensors, but i never found one that was inaccurate at the control panel! the resistance ALWAYS matched the chart and the resistance chart ALWAYS matched the control panel...but the resistance RARELY matched the actual!
    "Right" is not the same as "Wise".

    Don't step on my favorite part of the Constitution just to point out your favorite part.

  13. #13
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    Just replaced a saturated condensor sensor last week and I have to agree with graham.

    Pulled the old wiring out and rewire tied back to the control board. I have seen a few with those blue wirenuts at the sensors and I just cannot remember ever seeing a new unit show up that way.

    Maybe its a little overkill but I cut out the old ties and use the mounts for the new ties. I just like the equipment to be neat and clean.
    I'm good at making things cold...You can ask my first two wives!

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