AC Quality Care Rebate Program. Technical Training and SA Mobile Introduction

Transcription

1 AC Quality Care Rebate Program Technical Training and SA Mobile Introduction

2 Title 24 Slides Throughout this presentation the LOGO in the upper right corner indicates the information presented is part of the California Title 24 Part 6, requirements. All other slides are part of Build It Green, PG&E Quality Maintenance Program 1

3 Why are there programs? Energy Consumption per Capita 2

4 Why are there programs? Growth of Central Air Conditioning 3

5 Why are there programs? Residential Peak Usage 4

6 ACCA 4 Quality Maintenance Program WELCOME! 5

7 Agenda and Objectives Program Details What is the ACCA Standard 4? The Homeowner Interview ACQC Objectives The Air Distribution System NGAT Appliance Safety Testing 6

8 Agenda and Objectives Introducing SA Mobile Evaluating and HVAC System Refrigeration Cycle Testing Work Order Completion Program Documents Sitting with your Customer (General Discussion) 7

9 AC Quality Care Objectives After completion you should be able to: Explain why Airflow is critical Perform the ACCA 4 inspections using the SA Mobile application. Recommend retrofits needed to achieve minimum airflow Assess duct repair work 8

10 Program Incentives ACCA Standard 4 Assessment..$75 Refrigerant Charge Adjustment...$50 Efficient Fan Delay.$50 Blower Motor Replacement..$300 Airflow Correction $500 One Year Maintenance Agreement $50 Comprehensive Kicker. $100 (Requires Maintenance agreement and two additional measures) 9

11 Program Details PG&E s AC Quality Care Rebate Program utilizes the ACCA Standard 4, which supports increased HVAC performance baseline conditioning and enhanced planned maintenance of HVAC units. 10

12 Program Details Contractors and Technicians participating in this program use their expertise to make their customer s HVAC systems more energy efficient helping to accomplish a Peak Load Reduction in the State of California. 11

13 Program Details All Homeowner s could benefit from the type of service and communication that will be learned here today. Unfortunately not all of your customer s can benefit from the rebates offered as part of the AC Quality Care Rebate Program. 12

14 Tech Qualifications Technician(s) must have a minimum of two years HVAC field service, EPA certification type II or Universal and approval by BIG. Tech(s) must be listed on exhibit D and receive approval by BIG prior to program participation. Contactors Performing Airflow Measure Contractor must have on staff or subcontract a certified BPI Analyst with one day Advanced Training to perform NGAT Pre and Post test and must be approved by BIG prior to performing Airflow Correction. In lieu of a BPI Analyst, the contractor can elect to send a tech(s) to a PG&E 6 Day NGAT Training and will require approval by BIG prior to performing Airflow Correction. All must have been active in the last 12 months. 13

15 Customer Eligibility To participate in this program, customers must: Live in a Home powered by PG&E with it s own electric meter. Live in a Single Family home or Duplex. NO MOBILE, OR MODULAR HOMES. Have a Ducted Central Air Conditioning System (s) and/or a Central Heat Pump System. 14

16 What is the ACCA Standard 4? Residential HVAC Maintenance Standard Developed by contractors, manufacturers and mechanical engineers Written as an ANSI standard (can become code) Sets a minimum acceptable level of maintenance for residential systems 15

17 Goal of the ACCA Standard 4 The checklists that make up the standard were written to ensure that HVAC systems: Perform Reliably Provide Occupant Comfort Maintain Indoor Air Quality Operate in an Energy Efficient Manner MR18&23 16

18 What Does the ACCA Standard 4 Do? Sets inventory, inspection and maintenance requirements for residential systems Systems such as split systems, packaged DX, furnaces, boilers, heat pumps, evaporative coolers, etc MR18&23 17

19 What Does the ACCA Standard 4 Do? Split Systems, Packaged DX, Natural Gas Furnaces, and Heat Pumps are eligible for this program Single Family and Duplex Homes 3 stories or less Neither ACCA 4 nor this program supersedes any environmental, health or safety regulations 18

20 ACCA 4 Standards In the performance of the ACCA 4 Inspection, data is collected and recorded in SA Mobile. The HVAC system is cycled to determined proper functionality. Filters must be replaced at the time of the ACQC ACCA 4 inspection and dated. Condensers must be washed and fins straightened. 19

21 ACCA 4 Standards A customer insisting that he keep his filter or in the event the filter is clean upon inspection, that information should be noted on the filter as well as the date of the filter inspection. If the total static is greater than 1 iwc, explain to the customer the performance impact this will have on the system. - Reduced airflow - Potential icing of coil and compressor damage Customer filters that result in a total static of greater than 1 iwc - May not receive Refrigeration Adjustment or Airflow Correction until corrected to result in total static between.5 to 1 iwc 20

22 ACCA 4 Standards Condensers that are 15% or more deteriorated may not participate in a Refrigeration Charge Adjustment. In order to perform a Refrigerant Charge Adjustment, the Total Static Pressure must be between.5 and 1.0 iwc and the airflow calculation performed in SA Mobile must be a minimum of 350 cfm/ton. 21

23 Reporting to Customer Code Requirements - Identify and report code issues Performance Objectives Manufacturer s performance data Homeowner requirements for safety, efficiency and comfort Condition of existing duct system Appliance Safety issues Note: The NGAT Pre and Post is only required if airflow correction will be performed. 22

24 Inspection Frequencies If unacceptable conditions or performance are found during two successive inspections (Section 7.4.2) The owner should be notified and possible causes should be investigated, such as Poor field practices Insufficient time budgeted for task Repairs pending such as refrigerant leakage resulting in re-occurring low charge Design issues Obsolete equipment External factors Depending on investigation, inspection frequency or maintenance task may need to be adjusted 23

25 Documentation Requirements Documentation (Section 5.0) for the maintenance program should include at least: Inventory of the HVAC equipment, controls, components and accessories A list of inspection and maintenance tasks Code violations Performance objectives External conditions Inaccessible items Catastrophic duct disconnects or blockages Zoning controls and/or bypass issues Recommended corrective actions 24

26 Maintenance Inspection Tasks Quality Maintenance Program Requires Completion of the following ACCA 4 Checklists Checklist Equipment 7.1 Air Distribution System 7.3 Gas Furnace 7.6 Evaporator Coil 7.7 Condensing Unit 7.8 Fan Coils 25

27 Air Distribution System Duct air flow capacity assessment Foundation for Duct Retrofit and Restoration Duct system assessment Visual inspection Return plenum ducts Supply plenum ducts Inventory duct sizes in SA Mobile to achieve a minimum of 350 cfm/ton Open all registers Turn on blower in high speed or cooling mode and check for air flowing out of each register 26

28 Air Distribution System (cont.) Procedure Sum potential air flow using SA Mobile Air Distribution Test In 7.1 Compare to target air flow (350 cfm/ton) Repeat for supply If automatic damper zoning installed follow enhanced procedures Enter supply and return duct sizing in SA Mobile Air Distribution Test In

29 Natural Gas Appliance Pre-Test Prior to performing the Airflow Correction measure: - The home must pass the Natural Gas Appliance Test noted in SA Mobile as the Pre-Test. - The NGAT Pre-Test as well as the Post-Test, must be performed by a Certified BPI analyst with the one day advanced training, or the Pre and Post test could be performed by a technician who has attended the PG&E 6 Day NGAT training and has been active within the last 12 months and approved BPI or NGAT certified must be approved by BIG. 28

30 Duct System Repair Pre-Test Prior to performing an airflow correction, the home must have a Natural Gas Appliance Pretest performed by a BPI certified analyst with the one day advance course or a technician who has undergone the PG&E 6 day training as well as approval by BIG. NGAT protocol must be followed and any deficiencies found must be mitigated prior to performing an Airflow Correction. 29

31 Duct System Repair Post-Test When the Airflow correction has been completed, a Natural Gas Appliance Post Test must be performed by a BPI certified analyst with the one day advance course or a technician who has undergone the PG&E 6 day training and approved by BIG. NGAT protocol must be followed and any deficiencies found must be mitigated and the Post Test must be a Pass 30

32 Duct System Repair All work to use UL181 materials and T24 standards approved methods All accessible duct work treated Major sites of leakage Take-off collars on plenums where are the highest pressures Sheet metal fittings Duct board triangles and boxes Boot connection to duct and gap between boot and drywall or floor Duct mounting for aerodynamic airflow Runs are straight No kinks or twisted turns Flex ducts are fully extended Insulation R-4.2 minimum (Existing insulated Ducts) new Duct (R-6.0, R-8.0 zone dependent) Plenums insulated Outer jacket in place 31

33 CEC Title 24 Ducts Sheet metal duct and collar sealing 32

34 CEC Title 24 Ducts Sheet metal fittings to flex duct connections using Mastic 33

35 CEC Title 24 Ducts Sheet metal fittings to flex duct connections using Mastic 34

36 CEC Title 24 Ducts Proper flex duct mounting and routing to maintain aerodynamic air flow. 35

37 CEC Title 24 Ducts Flex Duct R-values for various insulation thicknesses 36

38 Hall of Shame We want to see your before and after pictures for the Duct Restoration Hall of Fame 37

39 Refrigerant Charge Adjustment Prior to performing the Refrigerant Charge Adjustment: - The condenser may not exceed 15% damage - Airflow must be a minimum of 350 cfm/ton And the total static pressure must be.5 to 1.0 iwc. before or after correction (both conditions must be satisfied) - Locking Caps are REQUIRED only after performing a Refrigerant Charge Adjustment. 38

40 Refrigerant Charge 39

41 Bent Fins 40

42 Determining Condenser Corrosion/Damage Measure the total surface area of the condenser in square inches. Measure the damaged or corroded section(s) in square inches. Divide the damaged area by the total area and multiply by 100 to determine percent of damage. Example: 37in sq. damaged. 418in sq total surface area. 37/418 =.088 X 100 = 9% damage. OK to perform Refrigerant Charge Adjustment 41

43 Three Types of Pressure 1. STATIC Bursting pressure. The pressure exerted against the sides of the duct. 2. VELOCITY The pressure created by the flow of air through the duct. 3. TOTAL The combined effect of both static and velocity pressure. 42

44 Analog Manometer - Test Equipment Dwyer No 170 Incline Gage Dwyer Magnehelic Dwyer Mark II Gage 43

45 Digital Manometer-Test Equipment Dwyer Series 475 Mark III UEI EM200 Retrotec DM2 Energy Conservatory DG 700 Either Digital or Analog test equipment are usable as long as they are approved by this program 44

46 External Static Pressure This is a combination of all the static pressure (return and supply) outside of the air handler. Abbreviated as ESP Return pressure, which is negative, and supply pressure, which is positive, is added together without regard for positive or negative to arrive at the total external static pressure.5 in. Every furnace and air handler has a blower performance table External Static Pressure is the Total Difference Between Supply and Return Pressure 45

47 Probe Locations The supply probe is installed at the supply discharge of the air handler with the probe pointing into the supply air stream The return probe is installed at the return air entry point of the air handler with the probe pointing into the return air stream 46

48 Cooling Airflow External Static Pressure by Component Pressure Drop, IWC Supply Coil Return

49 Safety, Everybody's Business PG&E ACQC Program Toolbox Safety Topics 2011

50 Safety Topics Covered Think Safety First When out in the field! Electrical Safety Ladder Safety Tool Safety

51 Electrical Safety Did you know that over 1,000 workers are killed by electricity annually with another 30,000 plus injured This is from working or coming in contact with live electrical without proper protection or not having turned off the power prior to the start of work 2011

52 Electrical Safety Severe electrical shock can cause the following serious, and life threatening injuries Ventricular fibrillation resulting in cardiac arrest Loss of limbs and eyes Severe burns, tissue damage, muscle damage and kidney failure 2011

53 2011 Electrical Safety

54 Electrical Safety Death by electrocution resulting in ventricular fibrillation, doesn t need a lot of current It only takes about 100 milliamps for a few seconds running through your body to cause Ventricular fibrillation and kill you, compare this to a 100 watt light bulb which is about 909 milliamps 2011

55 Electrical Hazards to Avoid Electrical hazards can be in the home and in crawl spaces so be alert and watch out

56 Electrical Hazards to Avoid Electrical hazards can be in the home and in crawl spaces so be alert and watch out

57 Proper Ladder Safety

58 Improper Ladder Use

59 Tool Safety Eye injuries are quite common, metal shavings from drilling or grinding, or wire bristles from wire brushes can fly off and enter the eye that is why eye protection should always be worn Power saws can cause amputations of fingers or limbs Broken bones and head injuries can result from tools falling from heights A tool falling from above to an unprotected head could be lethal always wear a hard hat 2011

60 2011 Tool Safety, Protect Eyes and Limbs

61 2011 Tool Safety, Be Aware of What You Are Doing

62 Introducing SA Mobile 61

63 The SA Mobile Application SA Mobile is an HVAC management software with patented refrigeration diagnostic algorithms. Key Aspects of SA Mobile: Maintenance Task Check Lists Data Collection and Storage Data Access and Report Generation Recommended Repairs 62

64 Installing the Application 63

65 Loading the SA Mobile Application On the Home Screen you will find Applications that have been installed and shipped with your Device. Locate your Device s Web Browser and tap to launch. Google Chrome is the recommended browser for SA Mobile Internet connection required for initial installation 64

66 Loading the SA Mobile Application If you have an Internet Connection your Browser should open to your default Home Page. Tap on the Web Address Bar to begin to typing the address where SA Mobile can be found for download to your Device. 65

67 Loading the SA Mobile Application Enter and tap the Go button to begin your Download. The installation of the Software is automatic but could take several minutes to complete depending on your connection speed and signal strength. Download progress will indicate the status of the Software transfer. 66

68 Creating a New Customer Site 67

69 Creating a New Customer Site To create a Site you will need the Customer s: Name Address City and State Phone Number Utility Tap in the Name Cell to Activate the cursor and Keyboard. 68

70 Creating a New Customer Site You have now created and opened a Customers Site. From this Screen you can: Check Site location for accuracy. Call the Customer Complete Specialized Site Tasks. Create and Add Units 69

71 Conducting the Homeowner Interview 70

72 Conducting the Homeowner Interview Before getting started you should talk to your customer about some of the simpler, often overlooked, things like: Comfort in the Home Operation of the system Specific areas of concern Keeping this conversation in mind will bring a new level of focus to every task you accomplish. Listening has been undervalued. 71

73 Conducting the Homeowner Interview Talking to your customer is as important as any service you, the technician, provide. A simple dialogue will: Put you customer at ease by making them feel heard. Set expectations around your visit by discussing what will be accomplished. Give you specific areas for improvement that, when addressed, will leave your customer completely satisfied. 72

74 Adding a Unit 73

75 Adding a Unit Creating an inventory is as easy as reading a few nameplates. The information entered will help track the equipment you encounter and set thresholds used when evaluating a systems performance. Care should be taken when entering data because this information will become a permanent record for this equipment. This record can be used for tracking, reporting, and analyzing system performance. A little time now equals better information later. 74

76 Adding a Unit Once the unit has been named and unit type selected, you will need to provide some information on the following: Air Handler Make Model Serial Indoor Metering Device Drive Type Speed Control Condenser Make Model Serial System Efficiency Refrigerant Subcooling Goal System Capacity And DON T forget the PG&E Sticker Number! 75

77 System Assessment Test In The first section you will need to complete is the Test In Section. This is the as found condition of the equipment on site. Any improvements or repairs will be listed here for discussion with the homeowner. Tap on 7.1 Air Distribution System to get started. 76

78 Checklist 7.1 Air Distribution 77

79 7.1 The Air Distribution System More than 30% of Residential ductwork falls short when we consider Sizing, Sealing, Routing, and Insulation. Problems in these areas lead to a host of problems including: Hot and cold zones in the home. Increased energy costs. Decreased indoor air quality 78

80 Dry Climate (California) Cooling System Airflow CFM/Nominal Ton

81 7.1 The Air Distribution System Walking through SA Mobile s Air Distribution Checklist will bring to the surface everything that a home s duct system might need. This check list focuses on the System s: Filter type and airflow potential Supply and Return Sizing Need for sealing Insulation 80

82 7.1 The Air Distribution System The Filters SA Mobile s Filter Calculations evaluate the filter (s) impact on the system by determining the airflow potential and comparing it to the system s requirements. We begin by counting the number of stand alone filters and filter returns and entering them in to SA Mobile. 81

83 Filter 82

84 2013 Table C 83

85 2013 Table D 84

86 Common Pressure Drops (PD) Component Pressure Drops IWC Cooling coil Filters Pleated Filters Electrostatic Filters Disposable RA Grilles and SA Diffusers ACCA Manual D 0.03 Transitions, Boots Elbows, (Use Turning Vanes)

87 Interesting Report prepared by Davis Energy Building America 2009 Annual Report Consortium for Advanced Residential Buildings 86

88 Interesting Report prepared by Davis Energy Building America 2009 Annual Report Consortium for Advanced Residential Buildings 87

89 Interesting Report prepared by Davis Energy Building America 2009 Annual Report Consortium for Advanced Residential Buildings 88

90 Interesting Report prepared by Davis Energy Building America 2009 Annual Report Consortium for Advanced Residential Buildings 89

91 Supplies and Returns Number and Diameter 90

92 7.1 The Air Distribution System The Return The System Return Select the duct connection and location from the appropriate drop downs Count the number of return air duct trunks and enter a quantity in the space provided. Select the shape of the duct from the drop down menu. Next enter the dimensions for each trunk first length and then width. 91

93 7.1 The Air Distribution System The Supply The System Supply Select the duct location from the appropriate drop down. Count the number of supply duct trunks and enter a quantity in the space provided. Select the shape of the duct from the drop down menu. Next enter the dimensions for each trunk first depth and then width. 92

94 7.1 The Air Distribution System Inspection The Inspection Section Please note the filter type. Inspect the supply plenum, connections, and seams. Inspect for disconnected ducts. Inspect platform returns In situations where the technician finds any of these areas to be unacceptable a proposed solution will be entered in the space provided. 93

95 7.1 The Air Distribution System Inspection Duct Sizing As it turns out, undersized duct systems with high-friction fittings, major air leaks, excessive run lengths, and crippling twists, kinks, and bends are the norm in the U.S., not the exception. A 1994 Department of Energy study estimated that nationwide, heating and cooling systems were operating at 60% of the designed airflow because of undersized ductwork. 94

96 Air Distribution System - Inspection The Air Distribution System Test-In has been performed, and it has been determined and agreed upon by the customer that airflow correction is an accepted recommendation then: - An NGAT Pre-Test must be performed and the result must be a pass prior to proceeding with airflow correction. - Any failures or deficiencies must be corrected prior to proceeding with airflow correction. - At the conclusion of the airflow correction the NGAT Post- Test must be a pass, any deficiencies must be corrected. 95

97 NGAT Pre-Test 32 drop down choices 96

98 NGAT Post-Test Fill in text boxes to select types and quantities of Gas Appliances 97

99 NGAT Post-Test 95 or more drop downs and fill ins, depending on appliances selected 98

100 NGAT Pre and Post The NGAT Pre-Test is more of a visual inspection. - Checking for safe appliance condition and operation - Gas leaks - Sufficient CVA These must be corrected prior to Airflow Correction NGAT Post-Test - Confirms that the home is in safe condition and passes NGAT and any required corrections have been performed 99

101 A Recommendation As A Recommendation Even though CO and draft readings are not taken on Pre-test, it would be wise to perform some CO readings and even appliance draft tests to avoid a surprise to you and the customer after airflow correction has been accomplished. Especially on the furnace, a gas log fireplace, or gas fireplace insert. If you determine an NGAT failure you need to advise the customer and make the repairs or call GSR both in Pre and Post Test You may walk into a situation where a correction such as increasing or adding CVA will not be possible, or that an appliance may not pass a Post-Test such as the fireplace insert, you may want to consider not to proceed with an Airflow Correction. 100

102 Checklist 7.6 The Evaporator Coil 101

103 7.6 The Evaporator Coil SA mobile s Evaporator Coil Checklist follows the ACCA Standard 4 section 7.4. During the inspection the technician evaluate the components that make up the evaporator section. Each component will be deemed as acceptable or unacceptable. In cases where Unacceptable is the choice a proposed solution will be noted. 102

104 7.6 The Evaporator Coil During the Service the technician should inspect: Condition of the cabinet and fasteners Condition of the condensate pan and drain line The condition of the condensate Pump. The production of condensate. For any signs of refrigerant leaks. The suction line insulation. The evaporator fins: Clean and Straight? TxV sensing bulb mounting and insulation if applicable. 103

105 7.6 The Evaporator Coil With system off Ensure fins are straight Clean to remove debris blocking air flow Inspect refrigerant line, joints, components and coil for signs of leakage Insulate refrigerant suction line If TXV present attach and insulate per program requirements With system on Measure dry bulb temperature difference across the coil Measure pressure difference between the supply and return plenums 104

106 Checklist 7.7 The Condensing Unit 105

107 7.7 The Condensing Unit SA mobile s Condensing Unit Checklist follows ACCA Standard 4 section 7.7. During the inspection the technician evaluate the components that make up the condenser. Each component will be deemed as acceptable or unacceptable. In cases where Unacceptable is the choice a proposed solution will be noted. 106

108 7.7 The Condensing Unit Fourteen (14) Tasks for AC with Three (3) additional tasks for Heat Pump Cabinet integrity 2 tasks Electrical 7 tasks Refrigeration 3 tasks Fan Motor 1 task Coil 1 task Heat Pump 3 tasks 107

109 7.7 The Condensing Unit During the Service the technician should inspect: Condition of the Cabinet and Fasteners Clearance around unit Electrical Supply and Disconnect The Equipment Grounding The Supply Voltage The compressor s amp draw. The fan motor s amp draw. The condition of the fan blades. 108

110 7.7 The Condensing Unit With system off Verify and repair as needed cabinet electrical disconnect meets code and is functional grounding meets code and is correctly wired all wiring connections tight and repair as needed capacitors and contactors Condenser coil Ensure fins are straight Clean or wash coil to remove debris blocking air flow Inspect refrigerant line, joints, components and coil for signs of leakage Insulate refrigerant suction line 109

111 7.7 The Condensing Unit With system on Electrical Measure and record incoming line voltage both high and low Measure and record amp draw of unit, compressor and fan motor Refrigeration System Diagnostic Procedure Measure indoor and outdoor temperatures and only continue if they are within the range required by the diagnostic software tool 110

112 7.7 The Condensing Unit With system on (cont.) Refrigeration System Diagnostic Procedure (cont.) Attach program approved gages and probes as directed by program protocol Run at least 15 minutes or until steady state operation is achieved Take the required readings Follow the software tool directions to first determine faults and then to correct them in the right order Complete final test showing the state of the refrigeration system 111

113 Refrigeration Cycle Testing MR1 112

114 Refrigeration Cycle Test In the event the condenser has 15% or greater damage, then a Refrigeration cycle test is not required. If the static pressure was outside the limits ( iwc) and the airflow was less than 350 cfm/ton then a Refrigeration cycle test is not required. Refrigerant Charge Adjustment is not a paid incentive when the above conditions occur. 113

115 Refrigerant and the Compressor Superheat is the heat absorbed into a substance over its saturation temperature. The temperature over the boiling point. The difference between the temperature we estimate from measuring the suction pressure and the temperature of the suction line entering the compressor. 114

116 The Condenser The refrigerant enters as a hot gas that is cooled to the saturation temperature in the De-Superheating section The Condensing section is where the refrigerant vapor becomes a liquid The Subcooling section is where the liquid is cooled down further 115

117 The Condenser Subcooling is the measure of the heat rejected from a substance below its saturation temperature The temperature below the condensing point The difference between the temperature we estimate from measuring the high- side pressure and the temperature of the liquid line leaving the condenser 116

118 The Diagnostic Screen 117

119 Example LT ST DB WB 80 MR1 118

120 Refrigeration Cycle Testing SA Mobile uses all of the required inputs and calculate four indices used to evaluate a systems performance relative to an expectation at the current driving conditions. ET = Evaporating Temperature SH = Superheat COA = Condensing Temperature Over Ambient. SC = Subcooling 119

121 Refrigeration Cycle Testing Safe and Reasonable Performance All four of the indices are within the acceptable range indicating that there is now further work to do. Systems in this condition are more likely to provide reliable performance and capacity for your customer throughout the cooling season. Comfort and Reliability is what your Customer wants. 120

122 High Head Pressure There are three causes for high head pressure 1) High side heat transfer problem This means the condenser is hot with no sign of over charge SA Mobile doesn t know if the condenser fans are running A high condenser air T with running fans proves a dirty condenser 121

123 High Head Pressure There are three causes for high head pressure 2) Overcharge When the subcooling is high it means there is a lot of refrigerant in the condenser 122

124 High Head Pressure There are three causes for high head pressure 3) Non-condensables A high condenser air T with running fans proves a dirty condenser If Tca is not hot, a standing pressure test will prove noncondensables non-condensables are unusual but not rare 123

125 High Head Pressure What about liquid line restrictions? Restrictions reduce the refrigerant flow to the evaporator This reduces the amount of heat absorbed in the evaporator With less heat to reject, the condenser is large compared to it s heat load Head pressure is lower 124

126 Questions and Answers WHY ARE HOME AIR CONDITIONERS A LOT LIKE CARS? THEY BOTH RUN BETTER AFTER A TUNE-UP. 125

127 126