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  1. reftec021702

    Chiller flow switch troubleshooting

    Dear fellows: I am working on a YORK 100-ton chiller which fails to start every morning. According to the operator, the display indicates a no flow condition, even with the chilled water pumps running. Sometimes a little bump to the flow switch casing is what is needed to get the chiller...
  2. reftec021702

    adding oil in lon line installations

    Dear people: Most manufacturers list on their installation manuals the right amount of REFRIGERANT PER FOOT of pipe needed for a complete charge. But what about the amount of oil that should be added in a long line situation if we wish not to starve the compressor of its lubtication...
  3. reftec021702

    Ductless split system piping

    Dear fellows: In my area, the installation of CEILING MOUNTED ductless split systems is becoming very popular, and whenever I see the piping job being done, one detail keeps bothering me: why most technicians do not put an inverted suction line trap at the point where the pipe comes out through...
  4. reftec021702

    Two stage DX cooling coil

    Dear fellows: Some field inspectors like to instructs us on installing solenoid valves at the liquid inlets of two-stage DX cooling coils. Could anyone tell me the reason for this? Are they really required or just optional? Thank you!!!
  5. reftec021702

    Supermarket rack question

    Dear fellows: I just got in charge of a parallel compressor low temp R-22 supermarket refrigeration rack. I have noticed that all of the compressors have factory supplied cartridge type suction filters. Do I need to change them periodically or just remove them after the initial installation...
  6. reftec021702

    expansion valve adjustment

    Dear fellows: I have two YORK 10-ton dual circuit evaporators not working at full capacity. Superheat measurements indicate values above 25 degrees F. I would like to reduce the superheat setting of the valves, but they seem to be of a fixed non-adjustable type. Is there any way to make them...
  7. reftec021702

    Water cooled condenser scale removal

    Dear fellows: Could someone please advice me on the correct method for de-scaling a water cooled condenser? If it is really done with a solution of phosporic acid, what are the mix proportions? Also, what kind of pump should I use to handle this solution? Thank you!!
  8. reftec021702

    Water cooled AHU tripping on start of system

    Dear fellows: I had inherited an interesting problem from another technician: a system of 14 water cooled TRANE Axiom 5-ton AHU, many of which trip on system starting. The sequence of the problem goes as follows: Water pump starts, flow established, 10 minutes later cooling tower No. 1 starts...
  9. reftec021702

    Classromm IAQ

    Thank you very much for all of your feedback. I must said that the classrooms do have an independent outside air injection system, including a pre-cooling coil, which is suppose to keep proper ventilation rates. I believe that board members are more concerned about in-room flu spread, not...
  10. reftec021702

    Classromm IAQ

    Dear fellows: I just finished the installation of some ductless mini split systems in a local elementary school. Everything working fine so far. Now, some school members are worried about flu transmission due to air recycling. Any idea on how to provide some additional sanitation to the air...
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