Heating Ventilation and Air Conditioning Diagnostics for Single Family Homes

Transcription

1 Heating Ventilation and Air Conditioning Diagnostics for Single Family Homes Vincent Pedalino FSL Home Improvements Phoenix, AZ 1

2 HVAC Basics Ways to improve the performance of existing air conditioning equipment without being a Certified HVAC Technician 2

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4 HVAC There are a lot of variables that affect how well an Air Conditioning system operates and not all have to do with the air conditioner Building Characteristics Orientation Insulation and Insulation Effectiveness Shading 4

5 HVAC Duct Sizing Equipment sizing Register size and location Pressure Balancing 5

6 HVAC What we will mostly be focusing on are issues with the mechanical equipment that we as Auditors, Crew Chiefs and Installers can visually inspect without having to access the sealed system or have an HVAC Certification or license 6

7 HVAC Identify Equipment Identify Specific Components Identify potential or existing problems that may impact equipment performance 7

8 Equipment Identification The first thing you need to know is how to identify what the existing piece of equipment is that your trying to inspect. Is the system gas or electric or both 8

9 Equipment Identification Heat Pump Straight Cool Electric Resistance Furnace Gas Furnace 9

10 Gas Pac 10

11 80% AFUE Gas Furnace 11

12 Evaporative Cooler ( Swamp Cooler) 12

13 Split System? 13

14 Half of a Split System 14

15 Electric Resistance Furnace 15

16 Equipment Identification You will want know how old the system is and what size is it. Tonnage kbtu s CFM 16

17 Equipment Identification This information is usually found on the nameplate of the equipment For Gas furnace s usually by the burner assembly For A/c units and Heat Pumps usually on the outside panel of the cabinet Tonnage will be in the Model number, number will be divisible by 12 (3 ton 36, 4 ton 48) 17

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21 HVAC System The OLD rule of thumb for sizing central a/c systems was 400 sq.ft. per ton There are 12,000 btu s in one ton of air conditioning i Sizing depends on the structure and the amount of BTU s needed to condition the space based on heat load Use Manual J to determine heat load Manual D to determine duct sizing Manual S to determine Mechanical system size 21

22 HVAC Systems In most homes we Weatherize in AZ, the OLD formula works for the type of housing we serve Newer construction ti that s t built well, insulated right, the ductwork is relatively leak free and the home is properly ventilated does not require as much heating or cooling On a Very well built home 800sq.ft. per ton is feasible. Smaller systems = cheaper to run, cheaper to install 22

23 HVAC Gather more information 23

24 HVAC Improving Performance and Efficiancyi Talk to the client about their utility bills Ask if there are hot or cold spots in the home Feel the air flow out of the supply registers Inquire about how old the unit is and if they have a service contract 24

25 HVAC Improving Performance and Efficiencyi The first thing I always check is the air filter. If it is dirty, replace it. Check for tight fit Proper placement for direction of air flow 25

26 Pleated Filter 26

27 Washable Filter 27

28 Air Filters Should be changed at least once a month Pleated filters can do a great job in trapping dust molecules They can also restrict airflow which can have a negative affect on comfort and efficiency I usually recommend the fiberglass type or the cheap pleated filters 28

29 Return Grill While you are checking the filter, also check the retun plenum The largest leaks are usually at the return on a relatively l tight duct system These are also the most important leaks to fix From my experience returns are typically y undersized 29

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32 Return Leak 32

33 Thermostats t Check location Should be on interior wall Should be close to the return air register Cycle the system with t stat to check operation 33

34 Digital it Thermostat t 34

35 Bi Metal Thermostat t 35

36 Mercury Bulb Thermostat t 36

37 Ductwork Inspect the ductwork What condition is it in Is it insulated Is it in or outside the conditioned space Is it installed correctly Is it the right size ( manual D) 37

38 How much ductwork do you really need? 38

39 One supply, One Return 39

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41 That s Better 41

42 Ductwork Duct runs should be short as possible and tight if using flex Minimal bends and elbows Supply registers should be located close to exterior walls Idea is to wash walls with conditioned air to keep envelope at comfortable temperature Return should be centrally located or one in each room 42

43 Leaking Supply Duct 43

44 Sealed Supply Boot to Drywall 44

45 Sealing Collars 45

46 Sealed Collars 46

47 Sealed A/C Elbow 47

48 Ductwork ALL connections and seams should be sealed with an UL approved duct mastic All duct sealing should be done per DOE guidelines Location of Supply and Return registers is very important Idea is to wash exterior walls where heat gain is Centrally located return or return in every room is preferred 48

49 Open Platform return 49

50 Open Platform Return 50

51 Sealing the Platform Return 51

52 Sealed Platform Return 52

53 Temperature Split With unit in Cooling, Check temperature split between the supply and the return with a thermometer Lt Let unit run for at least five minutes before bf doing di this Stick thermometer in closest supply register to the a/c unit and wait till reading settles Do the same thing in the return grill Should be about 20 degree difference 53

54 Static ti Pressure- How Much Resistance Using a static pressure probe and a Manometer or a pressure gauge, measure the static pressure on both sides of the evaporator coil Check unit rating usually.5 to.6 inches water column or 148 pascals (249 pascals = 1 water Column) Should be no greater than 1.0 WC Use Input button on DG-700 to convert to Inches of Water Column 54

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56 HVAC Inspection Access the a/c unit Disconnect power ( unplug or pull disconnect) Usually need a 1/4 or 5/16 nut driver to remove access panel 56

57 Pulling Disconnect / Fuse Block 57

58 Accessing the Components For Inspection 58

59 Visual Inspection Inspect wires for insulation overheating Make sure wires are connected tightly Look for signs of arcing / pitted contactors 59

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62 HVAC Inspection Check condition of coils Looks for signs of leakage (oil on coils) Check for bent fins Look for rust or deterioration 62

63 That s a dirty coil 63

64 Bent fins 64

65 Is that t a coil or an air filter? 65

66 New Evaporator Coil 66

67 Old Evaporator Coil 67

68 HVAC Inspection Check condition of Fan motors and Blades Should be no more than ¼ play on shaft Look for dirt build up on blower motor fan blades (squirrel cage) Check condition of capacitors ( no bulging) 68

69 Condenser Fan Motor 69

70 Run Capacitor 70

71 Run Capacitor on Blower Assembly 71

72 Blower Motor 72

73 Blower Assembly 73

74 Squirrel Cage Blower ( a little dirty) 74

75 Condenser Fan Motor 75

76 HVAC Inspection These are all, for the most part, just a simple inspection that might or might not substantiate a real problem. Overall condition of the equipment should always be checked The mechanical system itself may work just fine but other factors may be the reason the energy bill is high or the client is never comfortable 76

77 HVAC Inspection Always use the House as a System approach It s always important to check the effectiveness of the insulation Look for ways to reduce the heat gain ( or loss) 77

78 Is This Insulation Working? It s an R-30 78

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80 Insulation Opportunity 80

81 Shading 81

82 Solar Shade Screens 80% 82

83 Shade Screens 83

84 Improving Performance and Efficiencyi The number one thing a non technical person can do to maintain and possibly improve the efficiency of existing A/C equipment is always have a clean filter installed and clean the evap and condenser coils If the evap coil is not kept clean, air will not be able to move thru it causing ice to build up and eventually cover the entire coil 84

85 Improving Performance and Efficiencyi It is always cheaper to repair an a/c system then to replace it, but not necessarily more cost effective According to DOE Building America Performance Analysis All gas furnaces that are fairly maintained lose 1.5% AFUE per year All Heat Pumps that poorly maintained ( the majority of homes we work on) lose 3% SEER a year 85

86 Improving Performance and Efficiencyi So a 10 year old 10 SEER unit that was not regularly maintained and serviced would lose 30% of its installed SEER value making it a SEER of 7 If you have to spend $1500 to repair a unit that is still going to be a 7 SEER when you're done, is it worth it? Most common repairs are small and relatively cheap except for coil and compressor change outs. Run REM Design 86

87 Improving Performance and Efficiencyi Most repairs made to an a/c system are needed to keep the equipment functioning Parts are replaced when they breakdown and not many parts are replaced to make the unit more efficient System should be checked and serviced at least once a year for preventative maintenance 87

88 Improving Performance and Efficiencyi Once the basics are covered, it s time to call in a Certified HVAC Technician Check Amp draws Verify Airflow Check Refrigerant Charge Replace worn parts as needed or recommended. 88

89 SIZING Over-sizing has a negative effect on energy use, comfort, equipment life, and system costs: Oversized systems run for a short period and do not reach steady state efficiency (think of city vs. highway driving). Impacts both cost and life. Short run times mean that t the air does not get mixed, causing hot spots. Short run times will not remove humidity, increasing comfort problems. Over sized equipment costs more to install. Demand a Manual J Calculation 89

90 CALLING IN A CONTRACTOR Charging by pressure is not accurate Charging by touching refrigerant lines is not accurate Require Superheat and Sub-cooling - How much refrigerant is in the system - The flow of the refrigerant - The state of the refrigerant i.e., liquid to gas, gas to liquid 90

91 HVAC Inspection Refrigerant charge must be checked Ideally all duct leakage should be done first and airflow and static tti pressures bl balanced Demand superheat and sub cooling method to verify charge on a/c systems APS study in AZ. in the 90 s found 70% of units tested were severely under or overcharged Some overcharged by 100% 91

92 HVAC Remember, all other characteristics of the house should be considered when sizing equipment Manual J for load determination ti Manual D for duct sizing Manual S for equipment sizing and selection 92

93 Thank you. 93