This document provides an overview of HVAC systems with two parts: components and diagnosing issues. It describes the major components: furnace, air conditioner, heat pump, ducting, thermostat, line set, electricity, gas line. Each component is then broken down into smaller specialized parts and their functions are explained, such as the burner, blower, coils, fans, valves of the furnace. The air conditioner components inside and outside the home are also detailed. Thermostats, both mercury switch and digital, are reviewed. The document aims to educate homeowners on HVAC systems and when to call a technician.

1. HVAC
Heating Ventilating & Air Conditioning
By: Anthony D. Adams & Mark Gudde
March 2006
This HVAC presentation is made up of two parts;
Part 1; Components of the system and what they do
Part 2; Diagnosing service issues, when to call in the
technician

2. HVAC
• Today we will show you;
• The major components of the HVAC
system
• Smaller components of the system; what
they are called and what they do
• Diagnostics that you can do and when to
call the technician.
• There will be hand outs

3. Major Components
• The heating ventilation & air conditioning
(HVAC) system is made up of many large
components which are in turn made up of
many smaller specialized components.
First let’s see what the major components
of the system are. We will later break each
major component down into its individual,
specialized components.

4. Heating
• Forced air gas (fag)
furnace
• Add-on heat pump
(air source)

5. Air Conditioning
Condenser located outside
A-Coil located Inside

6. Ducting System
Ducts distribute the
conditioned air in the
home

7. Thermostat
• Thermostat monitors temperature (comfort
level), starts and stops the appropriate heating
or cooling system

8. Line Set
Line set distributes coolant (Freon) between
outside components, the condenser and
compressor, to the A-coil located inside the
home.
Line set composed of
one bare copper line
and one insulated
copper line

9. Electricity
Electricity provides the Power to Operate
Fans, Compressors, Thermostats,
Computer Boards, Switches, and Sensors
required for the various systems to
operate.

10. Gas line
Gas line brings the fuel to the fag furnace

11. Water Heater
Is the water heater
part of the HVAC
system?
Water Heater

12. Pop Quiz
What major components does it take to
provide the heating, ventilating, and air
conditioning for the homes we build?

13. Major system components
• Heating (fag)
• Cooling
• Add-on heat pump (heating)
• Ducting
• Thermostat
• Line set
• Electricity
• Gas line

14. Further Breakdown
• In this next section we will break down
these major components into smaller parts
and pieces and explain what role they play
in making the system work.

15. Heating (fag)
A-Coil

16. Heating (fag)
A-Coil

17. Heating (fag)
A-Coil

18. Heating (fag)
Burner/heat
exchanger

19. Heating (fag)
Burner/heat
exchanger

20. Heating (fag)
Burner/heat
exchanger

21. Heating (fag)
Burner/heat
exchanger

22. Heating (fag)
Blower

23. Heating (fag)
Blower

24. Heating (fag)
Blower

25. Heating (fag)
Blower

26. Heating (fag)
A-Coil
Burner/heat
exchanger
Blower

29. Pressure Sensing Switch

31. Draft Inducer Motor

32. Draft Inducer Motor

34. Gas Valve

35. Gas Valve

37. Burners

38. Burners

39. Burners

41. Roll out limit Switch

43. Flame Sensor

45. Igniter or glow plug

47. Main limit switch

49. Power Switch

50. Pop Quiz

51. Components at Burner Door
• Pressure Sensor Switch
• Draft Inducer Motor
• Gas Valve
• Burners
• Roll-Out-Limit Switch
• Flame Sensor
• Igniter
• Main Limit Switch
• Power Switch

54. Service Switch

56. Fresh air ventilation control

58. Control board

59. Control board
Close Up

60. 3 Amp Fuse

61. Diagnostic L.E.D.s

62. Pop Quiz

63. Components at Blower Door
• Service Switch
• Fresh Air Ventilation Control
• Control Board
• 3 Amp Fuse
• Diagnostic L.E.D.s’

64. Air Conditioning/Cooling
Air Conditioning Condenser

65. Air Conditioning/Cooling
Line Set
Connecting the Condenser and A-Coil

66. Air Conditioning/Cooling
Air Conditioning A-Coil

67. Air Conditioning/Cooling
Air Conditioning Condenser
1. Compressor
2. Condenser fan
3. Coil (like a radiator)
4. Service valve
7. Electrical service panel

68. Air Conditioning/Cooling
• Air Conditioning Condenser
Compressor

69. Air Conditioning/Cooling
Air Conditioning Condenser
Compressor

70. Air Conditioning/Cooling
Air Conditioning Condenser
Compressor

71. Air Conditioning/Cooling
Air Conditioning Condenser
Condenser fan

72. Air Conditioning/Cooling
Air Conditioning Condenser
Coil (like a radiator)

73. Air Conditioning/Cooling
Air Conditioning Condenser
Service valve

74. Air Conditioning/Cooling
Air Conditioning Condenser
Electrical service panel

75. Capacitor
Outside
thermostat Defrost control
board
Points

76. Air Conditioning/Cooling
Air Conditioning Condenser
Pop Quiz by the Numbers
1. Compressor
2. Condenser fan
3. Coil (like a radiator)
4. Service valve
7. Electrical service panel

77. Add on Heat Pump
Some Terminology & How it Works
• Reversing valve
• High pressure line
• Low pressure line
• Freon, gas or liquid?
• Heat is relative

78. Heat Pump Diagram

79. Heat Pump Diagram

80. Thermostat
Old style thermostat

81. Thermostat
Cover off exposing two mercury switches and wiring

82. Thermostat
Both mercury switches are circled and mercury is all the way
to the left of both switches therefore “no demand” condition
No demand

83. Thermostat
Note; Top mercury bulb has tilted. Mercury has flowed to the
right and made contact across the contacts.
Initial
demand

84. Thermostat
Note; Both vials have tilted enough so both vials
have mercury in contact across the electrodes
Full
demand

85. Present Day Thermostat
Digital