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

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

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

7. Refrigerant Floodback
METERING
DEVICE
TOO
MUCH
REFRIGERANT
FLOODED
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: Closing 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 > Valve will move open
1 + 4 < Valve will move close
1 + 4 = Valve will stay in position

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

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

13. “Balanced” Pushrod/Pin
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
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. Typical Example Indoor Coil 3 psi p Airflow Liquid Line from
Equalizer Line
Typical Example
Evaporator
Suction Header
Distributor 25 psi P
Indoor Coil
3 psi p
Airflow
Liquid Line
from
Condenser
Circuit Feeder Tubes
Bulb
TXV Feeler Bulb
From this slide we see how a direct expansion system is connected to a typical coil. The distributor assembly provides a connection point for the feeder tubes and also houses the nozzle.
Suction Line
External Equalizer Line

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

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

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 Liquid Line
Gauge Manifold Set
Refrigerant
Tank
Liquid Line
Digital Thermometer
Sensor
Flow Restrictor

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

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

24. Liquid Line Temperature
Correctly
Charged
Add
Refrigerant
Remove
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. COOLING MODE ONLY TXV Underfeeding Symptoms: Possible Causes:
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. COOLING MODE ONLY TXV Underfeeding Symptoms: Possible Causes:
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. COOLING MODE ONLY TXV Overfeeding Symptoms:
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. COOLING MODE ONLY TXV Overfeeding Symptoms: Possible Causes:
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: Possible Causes:
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. HEATING MODE ONLY TXV Restriction Symptoms: Possible Causes:
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 ABOUT OIL TEMPERATURES
BREAKS DOWN AT
350 F
Creates Contaminates
and
Accelerated Wear
VAPORIZES AT 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