HVAC qualification

1. HVAC 101
The Basics of Heating, Ventilation
and Air Conditioning
Presented by: Mike Barcik and Jeff Ross-Bain, PE
Southface Energy Institute

2. Southface Energy Institute
Sensible Solutions for Environmental Living
Energy
Code
Workshops
Greenprints
Commercial
Systems
EarthCraft
House
www.southface.org

3. HVAC
Heating, Ventilation and Air
Conditioning
Provides comfort for people
Allows humans to exist
under adverse conditions.

4. Comfort
Comfort is primary
intent of HVAC
systems.
Productivity
Building Durability
Health
Mold

5. Load Calculations
Heating and Cooling
Accuracy important!
Design conditions
Building shell load
R, U value
Internal load
Ventilation load
Infiltration
Occupancy schedules

6. Heat Transfer
Conduction
Convection
Radiation
Resistance (R-Value)
U = 1 / R
Q = U x A x ∆T
U-Value is the rate of
heat flow in Btu/h
through a one ft2
area
when one side is 1o
F
warmer

7. The amount of solar
heat energy allowed to
pass through a window
Example: SHGC = 0.40
Allows 40% through and
turns 60% away
Solar Heat Gain Coefficient

8. Psychrometrics
Dry bulb temp.
Wet bulb temp.
Humidity
Dew point
Moisture content
Heating
Cooling
Humidify
De-Humidify
Psychrometric Chart

9. Basic Refrigeration Cycle
Expansion
Valve
Compressor
Evaporator
Condenser

10. Basic HVAC Equipment
Fans / Blowers
Furnace / Heating unit
Filters
Compressor
Condensing units
Evaporator (cooling coil)
Control System
Air Distribution System

12. System Types and Common
Terms
Packaged Rooftop
Unit
Split System
Heat Pump
Geothermal
Air to Air
Hydronic (water)
PTAC / PTHP
Constant Volume
Variable Volume
Indoor Air Quality
Direct Expansion

13. Packaged Rooftop Units

14. FURNACE
A/C UNIT
Ductwork
Heating
and Cooling
Equipment
Temperature &
Humidity Controls
Split System

15. Heat Pump
• Operate on simple
refrigeration cycle
• Reversing the cycle
provides heating
• Temperature
limitations
• Air to air
• Water source
• Geothermal
• Lake coupled

16. Geothermal Heat Pump
Systems

17. Variable Air Volume
T T
Variable Speed
Return Fan
ReturnAir
Return Ducts
Zone Thermostat
Reheat Coil
VAV Box
Supply Ducts
Variable Speed
Supply Fan
Filters
CoolCoilw/TempReset
HeatCoilw/Temp
Reset
HVAC-17

18. Terminal Units
Variable volume:
Parallel
Constant volume:
Series

19. Hydronic systems
Pumps
Piping
Valves

20. Control Devices
Thermostats
 Manual
 Programmable
Optimum Start
DDC Systems
Variable Speed Drives
Automatic Valves and Dampers
Outdoor Sensors

21. Major Equipment
Chillers
Boilers
Cooling Towers

22. Economizers
Air Side Water Side

23. Economizers
Free cooling source: When available, use cool outdoor air
instead of mechanically cooled air.
55 o
F
80 o
F
Minimum supply
of outside air
Normal Operation
Outside air dampers are
positioned to provide the
minimum outside air
Economizer Operation
Outside air dampers are fully
open. Maximum outside air is
provided
80 o
F
55 o
F and
up
85%
outside
air
85%
exhaust
HVAC-23

24. Zoning and Economizers
• Economizers provide “free cooling”
when outdoor conditions are optimal
• Proper orientation & zoning yields
comfort & efficiency
N
S
W ECore
HVAC-24

25. Air Distribution
Ductwork
 Metal
 Flexible
 Ductboard
Grilles, Louvers,
& Registers
Dampers
 Shut off
 Fire
 Smoke
Sealants
Supports

26. Return Plenum Problems
HVAC-26

27. Additional Equipment
Energy Recovery Units
Desiccant Systems

28. Additional Equipment
Heat Exchangers
Humidifiers
Silencers

29. Mechanical Dehumidification
Return air is mixed with ventilation air
Cold coil condenses moisture
Heat is added back (electric or gas) so that room
air is not over cooled- Reheat
Filter

30. Historical Minimum Ventilation
Rates (cfm/person)
0
10
20
30
40
50
60
70
1835
1842
1849
1856
1863
1870
1877
1884
1891
1898
1905
1912
1919
1926
1933
1940
1947
1954
1961
1968
1975
1982
1989
1996
Tredgold
1836
Nightengale
1865
Billings
1895
Flugge
1905
Yaglou
1938
ASHRAE
62-73
ASHRAE 62-81
Smoking 62-81
ASH-
RAE
62-89
Smoking 62-89

31. Improved Ventilation Effectiveness
• Mechanically provide filtered and
dehumidified outdoor air to the
breathing space
• Vary ventilation based on the
number of occupants and process
loads - changes in occupancy can
be measured by CO2 sensors
• Consider designs that separate
ventilation and space conditioning
• Utilize heat recovery systems to
reduce system size and ventilation
energy costs

32. Improved Ventilation Effectiveness
Effective mixing of
ventilation air within space
Net positive pressure in
the southeast; exhaust
from appropriate spaces
Provide clean outdoor air,
avoid:
 loading docks
 exhaust vents
 plumbing stacks
 waste collection
 stagnant water

33. Additional Information / Resources
ASHRAE – The American Society of Heating,
Refrigerating and Air-Conditioning Engineers
 www.ashrae.org
Southface Energy Institute www.southface.org
Geothermal heat pump consortium
www.geoexchange.org
www.buildingscience.com
www.energycodes.gov