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TXV Devices

TXV Devices. Safety Review. Lock Out/Tagout Equipment Disconnect Switch. Read and Follow Specific Instructions in Manufacturer’s Service Literature. HVAC Technician Wearing Safety Glasses and Gloves. Remove Watches and Other Jewelry Before Servicing Equipment. The Compressor. METERING

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TXV Devices

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  1. TXV Devices

  2. Safety Review Lock Out/Tagout Equipment Disconnect Switch Read and Follow Specific Instructions in Manufacturer’s Service Literature HVAC Technician Wearing Safety Glasses and Gloves Remove Watches and Other Jewelry Before Servicing Equipment

  3. The Compressor METERING DEVICE EVAPORATOR CONDENSER COMPRESSOR

  4. EVAPORATOR (HEAT ABSORBED) CONDENSER (HEAT REJECTED) METERING DEVICE COMPRESSOR Heat Absorption & Rejection

  5. VARIES REFRIGERANT AS LOAD CHANGES EVAPORATOR (HEAT ABSORBED) CONDENSER (HEAT REJECTED) The Metering Device METERING DEVICE COMPRESSOR

  6. TOO LITTLE REFRIGERANT STARVED Compressor Failure METERING DEVICE EVAPORATOR CONDENSER COMPRESSOR

  7. Refrigerant Floodback TOO MUCH REFRIGERANT FLOODED METERING DEVICE EVAPORATOR CONDENSER COMPRESSOR

  8. DOE Efficiency Mandate January 23, 2006 Residential, single phase  65,000 Btuh cooling Minimum SEER = 13, up 30% from 10% SEER Minimum HSPF – 7.7, up 13% from 6.8% HSPF Applies to split system cooling and heat pumps Applies to packaged cooling and heat pumps No new standards for other products

  9. Bi-Flow TXV Hard Shutoff Balanced Port Extended Inlet Connection Thermostatic Element “Power-head” External Equalizer 3/8-in. SAE Outlet Connection Thermostatic Sensing Bulb “Balanced” Pushrod/Pin Superheat Spring Check Valve

  10. Forces Within a TXV • Force Description • Opening Force: • Pressure exerted on top of diaphragm and created by the temperature of the • bulb and refrigerant in the charge. • Closing Force: • Suction pressure exerted • under diaphragm. • Closing Force • Factory preset superheat spring. • Opening Force • Liquid pressure acting on pin area. • This force is eliminated in the • balanced port construction. Sensing Bulb Diaphragm Orifice Rules of Movement 1 + 4 > 2 + 3 Valve will move open 1 + 4 < 2 + 3 Valve will move close 1 + 4 = 2 + 3 Valve will stay in position

  11. Increased Load • Higher pressure in sensing bulb • Higher liquid line pressure • Valve forced open • More refrigerant to evaporator Sensing Bulb Diaphragm Evaporator Coil Orifice

  12. Decreased Load • Lower pressure in sensing bulb • Lower liquid line pressure • Valve forced closed • Less refrigerant to evaporator Sensing Bulb Diaphragm Evaporator Coil Orifice

  13. High Pressure Liquid at Valve Inlet Balanced Port TXV “Balanced” Pushrod/Pin Force created by high pressure liquid is “balanced”, and does not act as an opening force on the pin. High Pressure Liquid at Valve Inlet Spring Force With a conventional pin, high pressure liquid acts as an opening force pushing against the spring. As high side pressure changes, valve opening SH changes. Conventional Pin Spring Force

  14. Equalizer Line Evaporator Typical Example Suction Header Distributor 25 psi P Indoor Coil 3 psi p Airflow Liquid Line from Condenser Circuit Feeder Tubes Bulb TXV Feeler Bulb Suction Line External Equalizer Line

  15. Valve High Pressure Liquid at Valve Inlet CLOSED Seat Low Pressure Liquid with Flash Gas at Valve Outlet Check Valve Closed (Cooling) TXV controls liquid feed to evaporator Bi-Flow Operation (Cooling)

  16. High Pressure Liquid to the Outdoor Metering Device High Pressure Liquid from the Indoor Coil OPEN Check Valve Open (Heating) Flow from evaporator bypasses TXV Bi-Flow Operation (Heating)

  17. Feeler Bulb Locate the Feeler Bulb Properly

  18. Subcooling Subcooling is heat removed from liquid refrigerant after it condenses from a gas to a liquid. Example: 110° F Condensing Temperature - 102° F Actual Liquid Temperature 8° F Subcooling

  19. Subcooling Calculator

  20. Checking and Adjusting Charge

  21. Charge Procedure Service Valves Vapor/Suction Line Gauge Manifold Set Refrigerant Tank Liquid Line Digital Thermometer Sensor Flow Restrictor

  22. 10° F R410A Subcooling Calculator 395 psig 106° F

  23. 10° F R410A Subcooling Calculator MEASURED 395 psig 106° F

  24. Add Refrigerant Correctly Charged Remove Refrigerant Liquid Line Temperature 109° F +3° F 106° F -3° F 103° F REQUIRED FROM CALCULATOR MEASURED-105 F DEGREES

  25. Pressure/Temperature Card

  26. System Diagnosis

  27. TXV Underfeeding COOLING MODE ONLY • Symptoms: • Frost on valve or • indoor coil • Low pressure reading • at suction service valve • High superheat • HIGH liquid pressure at • liquid line service valve • Possible Causes: • Clogged filter drier • Liquid line restriction • Clogged TXV port • “Dead” TXV powerhead

  28. TXV Underfeeding COOLING MODE ONLY • Symptoms: • Frost on valve or • indoor coil • Low pressure reading • at suction service valve • High superheat • LOW liquid pressure at • liquid line service valve • Possible Causes: • Low refrigerant charge / • no subcooling

  29. End Result

  30. TXV Overfeeding COOLING MODE ONLY • Possible Causes: • Too much refrigerant charge • TXV bulb not attached to suction line • Check valve blocked open • Plugged external equalizer line • TXV stuck open • Symptoms: • HIGH pressure reading at suction service valve • Low superheat • LOW or normal liquid pressure at liquid line service valve

  31. TXV Overfeeding COOLING MODE ONLY • Symptoms: • LOW pressure reading at suction service valve • Low superheat • HIGH or normal liquid pressure at liquid line service valve • Possible Causes: • Blocked return air • Dirty air filter • Dirty coil • Indoor fan failure

  32. End Result

  33. TXV Hunting COOLING MODE ONLY • Symptoms: • Pressure reading at suction service valve is swinging more than ± 3 psi (6 psi total) • Superheat or suction temperature is swinging more than ± 4° (8° F total) • Possible Causes: • Blocked return air • Dirty air filter • Dirty coil • Blower fan failure • Low refrigerant charge

  34. TXV Hunting

  35. TXV Restriction HEATING MODE ONLY • Symptoms: • High pressure reading at suction service valve • Low pressure at liquid line service valve • Unit runs for short time and trips on compressor overload • Possible Causes: • Check valve stuck closed

  36. Compressor Discharge Gas Temp. 275 F Discharge Line Temperature Certain Failure 250 F Discharge Line Temperature Danger Level 225 F Discharge Line Temperature Maximum For Desirable Life

  37. KEY FACTS ABOUTOIL TEMPERATURES BREAKS DOWN AT 350 F Creates Contaminates and Accelerated Wear VAPORIZES AT 310 - 320 F Causing Rings and Cylinder Wear

  38. ARE THERE ANY QUESTIONS?

  39. Carrier Equipment Donation Program

  40. New Bargain List Process

  41. Benefits of the New Process • Reduces the process time from 2 months to 2 weeks • Provides for real-time available inventory tracking

  42. Program Highlights • On-line site tracks current inventory • Equipment is shipped direct to Vo-Tech School

  43. Distributor Requirements • Distributors will order via the on-line tool • The distributor will still be responsible for signing off on the “In-Kind Donation Report” • The distributor will forward the report with the “Thank You” letter

  44. Example: In Kind Donation Report

  45. Example: In Kind Thank You Letter

  46. What I Need From You • Your contact information • What do you need? (be specific) • Equipment information (space, electrical, etc) • A promise that the equipment is only installed at your vocational institute

  47. See Me After The Seminar For My Contact Information

  48. Thank You For Your Time

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