1. …just got better

2. Evacuation / Charging Superheat and Subcooling Charging Methods 2007

3. Evacuation

4. Moisture In A Refrigeration System
Visible Moisture
Water Droplets
Uncommon, but it can occur
Invisible Moisture
Water Vapor
Found in all gasses
Found in all solids
(READ SLIDE) Visible Moisture can occur when the system is left open to the elements. It is extremely detrimental to R-410A systems for moisture contamination to remain. Invisible Moisture can occur the same way but the droplets are not formed. In either case, moisture contamination is still a problem.

5. Visible Moisture Problems
Freeze Ups
Ice crystal formation will occur at the point of expansion, i.e.:
Capillary Tube
TXV
Flow Rator
This problem will be intermittent
When the system warms up the problem stops
(READ THE SLIDE)

6. Invisible Moisture Air in the piping “Wet” Refrigerant
Leaks Under a Vacuum Condition
Copper and Brass Components
System Components exposed to the atmosphere during assembly
(READ THE SLIDE)

7. Invisible Moisture Causes Corrosion
Moisture Will React With The Metals
Metal H2O Corrosion
(READ THE SLIDE)

8. Moisture & Refrigerant
Moisture Refrigerant Acid
Refrigerant that is contaminated with moisture will react to form acid in areas where heat is present.

9. Moisture & Refrigerant
CFC & HCFC & HFC
Hydrolyze to form Hydrochloric Acid
Hydrofluoric Acid
Acid Formation Is Accelerated By Heat
Copper and Brass Will Be Attacked
Plates Hot Surfaces
Bearings Seize
(READ THE SLIDE) So where in system is the most heat generated? The compressor. This is the area most affected by the acid.

10. Copper Plating
This picture shows the effect that plating has on a bearing journal. These are not grooves cut into the journal but copper buildup causing the clearances to close up and keep oil from coating the bearing surface. This compressor, of course, seized.

11. Moisture & Refrigerant & Oil
Metal Refrigerant Acid Oil
Sludge
When metal, refrigerant, acid and oil are present, they will mix and create a sludge. This will shorten the compressor life in R-22 systems and is literally a poison to R-410A systems.

12. So How Do We Get The Water Out?
We Boil It
We Can’t Raise The System Temperature To 212°F
So We Have To Lower the System Pressure To A Point Where Water Boils At Ambient Temperatures.
(READ THE SLIDE)

13. Pressure vs. Boiling Point
Physics 101
As The Pressure is Decreased - The Boiling Point Decreases
To Decrease The Pressure, We Could Raise The System To A Higher Altitude.
There Is Less Atmosphere Above Us On Pike’s Peak
Less Weight Of Air = Lower Air Pressure
(READ THE SLIDE)

14. Pressure vs. Boiling Point
At Sea Level
Atmospheric Pressure = 14.7 PSI.
Boiling Point = 212° F
On Pike’s Peak ( Elevation)
Atmospheric Pressure = 8.32 PSI.
Boiling Point = 184° F
This Is Still Not Low Enough
(READ THE SLIDE)

15. Pressure vs. Boiling Point
To Boil 80°F
The pressure has to be lowered to inches of mercury
To Boil 45°F
The pressure has to be lowered to inches of mercury vacuum or 7620 microns
(READ THE SLIDE)

16. What The Heck Is A Micron?
1 Inch = Microns
.039 Inch = 1000 Microns = 1 Millimeter
1 Micron = 1/1,000,000 meter
To Small To Measure With A Gauge.
(READ THE SLIDE)

17. How Is Vacuum Measured? Each Mark Represents 2” of Water Column
Each mark represents 2” of mercury vacuum. 1” equals 25,400 microns. Therefore, there are 50,800 microns shown at each mark. Assuming you have a perfectly calibrated set of gages, try to determine where in between the marks you would find 500 microns. It can’t be done. For that matter, just where on these gages would you find 29.62” of Mercury Vacuum indicated. Remember that this is just the minimum vacuum to insure that the moisture will boil out. If you don’t know for sure that you got it deep enough, you don’t know if your evacuation has been successful. Only lowering the boiling point to well below your ambient temperature can this be done.
Each Mark Represents
2” of Water Column
Or Microns

18. How Is Vacuum Measured? A Compound Gauge A Vacuum Gauge
Impossible To Determine
A Vacuum Gauge
The Resolution Is Not Suitable
Readings Change with Altitude (pressure)
A U-Tube Manometer
Resolution Is 1 MM of Mercury (That Equals 1000 Microns)
(READ THE SLIDE) None of these is acceptable for proper evacuation.

19. How Is Vacuum Measured? A Thermister Micron Gauge
Will Measure The Last Inch Of Vacuum
Atmospheric Pressure Has No Impact
High Resolution Readings Are Possible
Readings Go Down To 1 Micron
(READ THE SLIDE)

20. How Is Vacuum Measured?
Will accurately measure vacuum level in 10 segments from 25,000 to 50 Microns.
The LCD screen can be read even in direct sunlight and is designed to minimize battery consumption.
The durable carrying case protects the instrument and has a built-in compartment for storing the 24" charging hose (included).
(READ THE SLIDE) There are several levels of quality on micron gauges. Some of the less expensive kinds do not last very long. A good quality mid range priced unit is usually the best bang for the buck.

21. How Is Vacuum Measured? Other Tools of the Trade
Displays pressure in microns in steps of 1 micron. Has pump down indication showing progress from atmospheric pressure.
Range: 50 to 2000 microns of mercury.
Resolution: 1 micron of mercury.
Pump down indication: when pumping down from atmospheric pressure to 2000 microns, output of head goes from over 3VDC to 2VDC.
Straight-in access to sensor for easy cleaning.
Fitting: 1/4" flared brass fitting (male) .
Accuracy ±10%, microns of mercury.
Auto-off can be disabled for data logging.
"T" for inline vacuum testing.
This piece is a relatively inexpensive Micron Gage that is used in conjunction with a auxiliary mother instrument. Both instruments are required for it to function.

22. Thermistor Micron Gauge
This Gauge Measures The Thermal Conductivity Of The Gas Remaining in the Refrigeration System
It Has A Source Of Heat
It Has A Heat Receptor
The Thermistor
(READ THE SLIDE)

23. Thermistor Micron Gauge
Hose to System
Heat Source
Thermistor
The gauge is normally attached to the system using the hoses on the charging manifold. (READ THE SLIDE)
The more gas left---- The higher the Temperature on Thermistor

24. Thermistor Micron Gauge
Hose to System
Heat Source
Thermistor
(READ THE SLIDE)
Less Gas……..Less Heat Received….Lower Reading

25. Vacuum Pumps The Air Compressor Type It Does Move Large Volumes Of Air
It Cannot Achieve a Deep Enough Vacuum
It Can Achieve At Best 28” of Mercury Vacuum
No Water Would Be Boiled
In order to properly evacuate a system, it is necessary to use the proper type of vacuum pump. Some pumps that technicians used in the past will not adequately do this. Let’s go over some different types of pumps that are acceptable as well as some that are not. (READ THE SLIDE)

26. Vacuum Pumps The Piston Compressor Type The Rotary Compressor Type
At Best, It Can Achieve 29” Of Mercury Vacuum (at Sea Level)
That Will Not Boil Water Under 80F
The Rotary Compressor Type
It Can Achieve A 29.63” Of Mercury Vacuum (at Sea Level)
Water Would 45F
It Is, However, Unsuitable For Systems Larger Than Household Refrigerators
(READ THE SLIDE)

27. High Vacuum Rotary Vane Pumps
Single Stage
It’s Smaller
It’s Light Weight
It Pulls Down To 1000 Microns
Robinair Will Pull Down To 200 Microns
(READ THE SLIDE)

28. Single Stage
This slide indicates how the single stage vacuum pump functions.

29. High Vacuum Rotary Vane Pumps
Two Stage Vacuum Pumps
The Most Commonly Used Vacuum Pump For Service
It Has A Larger CFM Capacity
It Is Slightly Heavier Than The Single Stage Vacuum Pump Of The Same Capacity
It Can Achieve A Deeper Vacuum Than The Single Stage Vacuum Pump Because The Second Stage Takes Over At The Point The 1st Stage Stops
(READ THE SLIDE)

30. High Vacuum Rotary Vane Pumps
Two Stage (cont..)
These Vacuum Pumps Can Pull Down To One Micron
Robinair Guarantees Its Pump To Pull Down To 20 Microns
(READ THE SLIDE)

31. Two Stage Vacuum Pumps
This is a simple illustration of how a two stage vacuum pump works.

32. Two Stage Vacuum Pumps ISO Valve 2nd Stage 1st stage
This is a cutaway of a Robinair two stage vacuum pump.

33. Rotor & Vanes Notice The Off Set Construction
The Vanes Come Out At Low RPM To Wipe The Interior Of Pump
The 1st Stage Vanes Are Ceramic, The 2nd Stage Vanes Are Aluminum
(READ THE SLIDE)

34. Gas Ballast Valve Mixes Dry Air With High Humidity Air
Reduces Moisture That Is Condensed Into The Oil
Makes Oil Last Longer
(READ THE SLIDE) How often is the oil changed in most vacuum pumps? Using the Gas Ballast Valve helps but does not allow you to wait an excessive amount of time before changing oil. The pump will lose its ability to pull a deep vacuum if the oil is too old.

35. Gas Ballast Valve
Open The Valve At The Beginning Of The Evacuation Process
When A level Of 1000 Microns Is Achieved, Close The Valve
(READ THE SLIDE) As you can see, use of the Gas Ballast Valve is a very simple process.

36. Issues That Affect The Speed Of Evacuation
The Size of Vacuum Pump
How You are Hooked Up To the System
High & Low Side
The Size of Hoses
Access Fitting?
The Ambient Temperature
The Size of The System
The Complexity of The Piping
The System Components
Oil Separators
Accumulators
Valves
(READ THE SLIDE) A point to remember here is that if you don’t pull a vacuum deep enough to lower the boiling point of the moisture to well below the ambient temperature, you will not remove the moisture in the system

37. Speed Of Evacuation Use The Largest Hoses You Can
Add Heat To Areas Of Restriction
Get the Access Fittings Out Of The Way
Measure The Vacuum At The System
Isolate The System And Equalize It To Get A True Reading
(READ THE SLIDE) In most cases, the quarter inch hoses on your manifold set are large enough for residential purposes. Adding heat does not mean to fire up the torches and heat the compressor up. What access fitting are we talking about here?

38. Access Core Removal Tool
This is the tool that is used to safely remove the Schrader Valve and then replace it after a successful vacuum is attained. The new style uses a ball valve shut off. This new one is becoming very popular.

39. How Much Pump Do You Need?
Vacuum Pumps Are Rated In Cubic Feet Per Minute Of Free Air Through the Pump
As A Rule Of Thumb
1 CFM Per 7 Tons Of System Is Adequate
I.E. A 6 CFM Rated Pump Will Be Good For 42 Tons Of System Capacity
Multiple Pumps Are OK
(READ THE SLIDE)

40. Evacuation Set Up
This slide show a typical manifold hook up to a system for evacuation and charging.

41. Evacuation With Micron Gauge
This graph shows just how valuable a micron gauge can be. Notice how quickly a technician can determine the condition of a system. In just a very few minutes, the tech will know if he has a tight, dry system, if additional vacuum is required to finish removing the moisture or if there is a leak in the system. Knowing this information this quickly will enhance the performance and accuracy of any technician. It will also cut down on call backs for failed compressors due to moisture in the system.

42. CONDITIONS THAT AFFECT CHARGING ACCURACY
(READ THE SLIDE)

43. CHECK THE AIR FLOW MAKE SURE THE FILTERS ARE CLEAN
ASSURE THAT THERE ARE NO RESTRICTIVE FILTERS IN PLACE
IS THE BLOWER WHEEL CLEAN?
IS THE EVAPORATOR COIL CLEAN?
VERIFY THAT YOU HAVE 400 CFM’s OF AIRFLOW PER TON
(READ THE SLIDE) It makes no sense to charge a system if there is not enough air crossing the coil to function properly.

44. METERING DEVICES – Fixed Orifice (Capillary)
It is important that the technician recognizes the types of metering devices that will be encountered. Without this knowledge, it is very possible that the charging technique used by the tech will not be acceptable and will adversely affect the final charge on the system This slide shows a capillary tube system and is no longer being used with the higher efficiency equipment and must be replaced in 13+ SEER equipment and above. This system requires that the superheat method of charging be used.

45. METERING DEVICES – Fixed Orifice (Flowrator / Orifice)
This slide shows a Flowrator metering device which is the most popular at this time. It is important to size the orifice correctly for the condenser you are using. Don’t just take for granted that the installed orifice is the correct one. The Super Heat charging method is the one used to properly charge this system.
Orifice
Metering
Device

46. METERING DEVICES - TXV
This slide shows a TXV type metering device. A number of systems, especially the ultra high efficiency and heat pumps, use the TXV metering device. The proper way to charge this type of system is using the subcool method.

47. TEMPERATURE PROBE TEST POINT LOCATIONS
SUCTION LINE SERVICE VALVE
LIQUID LINE SERVICE VALVE
(READ THE SLIDE) The proper type of temperature sensing device is becoming more and more important. Technicians that are still using the “old ice pick with a dial” or “infrared” types of device should really consider changing. The proper type is the electronic thermister/thermocouple type that can be firmly affixed to your refrigeration lines and insulated. It is impossible to accurately read superheat and subcool without the proper equipment.

48. The picture shows a clamp on type of thermister
The picture shows a clamp on type of thermister. This sensor is connected to a multi-meter that has a “K” type of receptacle available. The multi-meter will process the information being sent to it by the sensor and display the temperature.

49. This picture shows the multi-meter that is attached to the clamp on thermister. and the manifold gauges attached to the system.

50. SATURATION POINT
THE TEMPERATURE AT WHICH AT A GIVEN PRESSURE, THE REFRIGERANT IS NEITHER 100% LIQUID NOR 100% VAPOR
IT IS THE POINT WHERE THE REFRIGERANT IS CHANGING STATE FROM LIQUID TO VAPOR OR VAPOR TO LIQUID
(READ THE SLIDE) At saturation point, you can add or remove heat and the temperature will not change. The heat added or removed is called latent or invisible heat because it cannot be felt. It is at this point that you get your maximum refrigeration effect. This is important to us because it is how we define Subcool and Superheat. Once the vapor becomes 100% liquid, any additional heat removed will be sensible heat and can be measured with a thermometer. This difference in the saturation temperature and the actual refrigerant temperature is called Subcool. Conversely, when 100% of the liquid has been turned to vapor, any additional heat added will be sensible heat that can be measured with a thermometer. This difference in saturation temperature and the actual refrigerant temperature is called the Superheat.

51. METHODS OF CHARGING REFRIGERATION SYSTEMS
WEIGHING METHOD
SUPERHEAT METHOD
SUBCOOLING METHOD
(READ THE SLIDE) Each of these methods will be discussed more fully.

52. WEIGHING METHOD
THIS METHOD CAN BE USED ON ALL TYPES OF REFRIGERATION SYSTEMS
DETERMINE THE PROPER WEIGHT OF THE CHARGE FROM THE DATA PLATE ON THE CONDENSING UNIT. THIS WILL USUALLY INCLUDE ENOUGH REFRIGERANT FOR THE STANDARD EVAPORATOR AND 15 FEET OF LINE SET.
MEASURE THE AMOUNT OF LINE SET INCLUDED IN THE SYSTEM. USING THE CHARTS IN THE INSTALLATION INSTRUCTIONS, ADD OR SUBTRACT THE PROPER AMOUNT OF REFRIGERANT TO DETERMINE THE FINAL CHARGE.
USING A CALIBRATED SCALE, ADD OR REMOVE REFRIGERANT BASED ON YOUR CALCULATIONS
(READ THE SLIDE) Weighing the charge has always been considered the best way to charge any refrigeration or air conditioning system.

53. SUPERHEAT METHOD
THE SUPERHEAT METHOD IS USED FOR SYSTEMS USING A FIXED ORIFICE TYPE METERING DEVICE
The Superheat method of charging is the method required to charge a system that utilizes any fixed orifice type metering device. In Goodman’s case, that would be the Flowrator. The orifice that is installed is based on the requirements for the condenser and can be found in the I/O manual.
Orifice
Metering
Device

54. SUPERHEAT METHOD
THERE ARE TWO WAYS TO CHARGE A SYSTEM USING THE SUPERHEAT METHOD:
USING DRY BULB RETURN AIR TEMPERATURE
USING WET BULB RETURN AIR TEMPERATURE
THE WET BULB RETURN AIR TEMPERATURE METHOD IS THE MOST ACCURATE
(READ THE SLIDE) Using the dry bulb method of Superheat charging is the method that has been used for years at Goodman. The problem with this method is that it does not take into consideration the Latent heat (moisture or humidity) that are influencing the system at any given time. The dry bulb method is best served in arid areas where there is not much humidity. If you serve an area that has relatively high humidity then you should probably use the Wet Bulb method of Superheat charging. Using the dry bulb method can cause the technician to overcharge the system.

55. USING DRY BULB RETURN AIR TEMPERATURE
SUPERHEAT METHOD
USING DRY BULB RETURN AIR TEMPERATURE
(READ THE SLIDE)

56. INSTALL THERMOMETER/THERMOCOUPLE
INSTALLED ON THE SUCTION LINE (LARGER OF TWO COPPER LINES )
INSULATE THE PROBE FOR A MORE ACCURATE READING
(READ THE SLIDE)

57. USING SUPERHEAT TABLE
GET THE OUTSIDE AMBIENT TEMPERATURE IN THE SHADE OF THE CONDENSING UNIT
GET THE RETURN AIR DRY BULB TEMPERATURE AT THE RETURN AIR GRILL
INTERSECT THE 2 NUMBERS ON THE CHART SHOWN ON THE NEXT SLIDE
THAT WILL GIVE YOU THE AMOUNT OF SUPERHEAT YOU NEED
(READ THE SLIDE)

58. EXAMPLE
AMBIENT OUTSIDE TEMPERATURE (IN THE SHADE OF THE CONDENSOR) IS 95°F
RETURN AIR (DRY BULB) Temperature IS 75°F
INTERSECT THE 2 NUMBERS AND YOUR SUPER HEAT WILL BE 5°F
(READ THE SLIDE)
Superheat Table

59. READING THE SATURATED PRESSURE/TEMPERATURE
READ THE LOW SIDE OF YOUR COMPOUND GAUGES
THE OUTSIDE READING IS YOUR PRESSURE
THE INSIDE (R-22) IS YOUR SATURATION TEMPERATURE
IF YOUR GAUGES DO NOT HAVE A INSIDE SCALE SHOWING SATURATION TEMPERATURE, THEN READ THE PRESSURE AND USE THE CHART AT THE RIGHT TO DETERMINE SATURATION TEMPERATURE
(READ THE SLIDE)

60. EXAMPLE YOUR LOW SIDE PRESSURE IS 75 PSI
DIRECTLY BELOW THAT NUMBER IS THE SATURATION TEMPERATURE, WHICH IS 44°F
TAKE YOU SUCTION LINE TEMPERATURE, WHICH IS 65°F
(READ THE SLIDE)

61. EXAMPLE SUBTRACT THE 2 NUMBERS AND THAT’S HOW MUCH SUPERHEAT YOU HAVE
65°F – 44°F = 21°F SUPERHEAT
WE ONLY NEEDED 5°F
ADD CHARGE TO LOWER SUPER HEAT
REMOVE CHARGE TO RAISE SUPERHEAT
(READ THE SLIDE)

62. USING WET BULB RETURN AIR TEMPERATURE
SUPERHEAT METHOD
USING WET BULB RETURN AIR TEMPERATURE
(READ THE SLIDE)

63. USING SUPERHEAT CALCULATOR
GET THE RETURN WET BULB TEMPERATURE AT THE RETURN AIR GRILL USING A SLING PSYCHROMETER OR METER CAPABLE OF READING WET BULB TEMPERTURE
GET THE OUTSIDE AMBIENT TEMPERATURE IN THE SHADE OF THE CONDENSING UNIT
SET ARROW TO INDOOR ENTERING AIR WET BULB TEMPERATURE
LOCATE CONDENSER ENTERING AIR DRY BULB TEMPERATURE
READ REQUIRED SUPERHEAT TEMPERATURE AT CONDENSER ENTERING AIR DRY BULB TEMPERATURE
ADD CHARGE TO LOWER SUPER HEAT
REMOVE CHARGE TO RAISE SUPERHEAT
(READ THE SLIDE) The readings obtained are only as good as the equipment monitoring them. Use a digital clamp on type of thermister to determine the refrigeration temperature.

64. SUBCOOLING METHOD
SUBCOOLING METHOD IS USED IN SYSTEMS THAT HAVE A TXV METERING DEVICE
Subcooling is the method of charging used on equipment utilizing TXV type metering devices.

65. CHECKING SUBCOOLING
Refrigeration liquid is considered subcooled when its temperature is lower than the saturation temperature corresponding to its pressure.
The degree of subcooling equals the degrees of temperature decrease below the saturation temperature at the existing pressure.
(READ THE SLIDE)

66. CHECKING SUBCOOLING
Attach an accurate thermometer or preferably a thermocouple type temperature tester to the liquid line as it leaves the condensing unit.
Install a high side pressure gauge on the high side (liquid) service valve at the front of the unit.
Record the Saturation Temperature from the scale on your Gauge. If you don’t have the Saturation Temperature Scale then record the gauge pressure. Note the temperature of the line.
If required, convert the liquid line pressure gauge reading to temperature by finding the gauge reading in the Temperature – Pressure Chart and reading to the left, find the temperature in °F column.
The difference between the Saturation Temperature (thermometer reading and pressure to the temperature conversion) is the amount of subcooling.
(READ THE SLIDE)

67. CHECKING SUBCOOLING EXAMPLE: Liquid Line Pressure = 260 psi
Corresponding Temp. = 120°F
Thermometer on Liquid line = 109°F
To obtain the amount of subcooling subtract 109°F from 120°F.
The difference is 11°F Subcooling.
Normal Subcooling Range:
9 to 13°F Subcooling for heat pumps units
14 to 18°F for straight cool units.
(READ THE SLIDE) An interesting example of the kind of problem technicians run into is this: If you are checking the subcool of a unit and determine that you have 100 Deg F. Saturation temperature and your thermometer reads a line temperature of 90 deg F, what is the subcool? It appears that you have 10 Deg F subcool. You wish the subcool to be 15 Deg F and add some refrigerant. You check again and find that you now have 110 Deg F saturation temperature and a line temperature of 100 Deg F. It appears that you still have only 10 Deg F subcool. What’s happening? What you are seeing is the amount of error between your gauges and your thermometer. You are still at saturation temperature as long as they follow each other up and down the scale. Once they start to separate, you are seeing your true subcool. With that in mind, you would add your error factor to the amount of subcool that you want in order to get a very accurate subcool charge.

68. Any Questions?
(READ THE SLIDE)
Thank you!

69. any questions?
thank you!