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Aa hvac 101
This document provides an overview of HVAC systems, including the basics of heating, ventilation, and air conditioning. It discusses key concepts like load calculations, heat transfer, psychrometrics, basic HVAC equipment, common system types, control devices, air distribution, and improved ventilation effectiveness. The goal of HVAC is to provide thermal comfort for occupants while allowing buildings to be used under various outdoor conditions.
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Aa hvac 101
- 1. HVAC 101 The Basicsof Heating, Ventilation and Air Conditioning Presented by: Mike Barcik and Jeff Ross-Bain, PE Southface Energy Institute
- 2. Southface Energy Institute SensibleSolutions for Environmental Living Energy Code Workshops Greenprints Commercial Systems EarthCraft House www.southface.org
- 3. HVAC Heating, Ventilation andAir Conditioning Provides comfort for people Allows humans to exist under adverse conditions.
- 4. Comfort Comfort is primary intentof HVAC systems. Productivity Building Durability Health Mold
- 5. Load Calculations Heating andCooling 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 ofsolar 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. Wetbulb temp. Humidity Dew point Moisture content Heating Cooling Humidify De-Humidify Psychrometric Chart
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- 10. Basic HVAC Equipment Fans/ Blowers Furnace / Heating unit Filters Compressor Condensing units Evaporator (cooling coil) Control System Air Distribution System
- 12. System Types andCommon 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
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- 14. FURNACE A/C UNIT Ductwork Heating and Cooling Equipment Temperature& Humidity Controls Split System
- 15. Heat Pump • Operateon simple refrigeration cycle • Reversing the cycle provides heating • Temperature limitations • Air to air • Water source • Geothermal • Lake coupled
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- 17. Variable Air Volume TT 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 Constantvolume: Series
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- 20. Control Devices Thermostats Manual Programmable Optimum Start DDC Systems Variable Speed Drives Automatic Valves and Dampers Outdoor Sensors
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- 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
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- 27. Additional Equipment Energy RecoveryUnits Desiccant Systems
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- 29. Mechanical Dehumidification Return airis 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 Effectivemixing 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
Editor's Notes
- #8 <number> Solar Heat Gain Coefficient (SHGC) The glazing’s effectiveness in rejecting solar heat gain. Part of a system for rating window performance used by the National Fenestration Rating Council (NFRC) Gradually replacing shading coefficient (SC) in product literature and design standards convert SC to SHGC by multiplying the SC value by 0.87
- #15 <number> An HVAC system consists of a heating and/or cooling source, a distribution system (e.g. ductwork or hot/chilled water piping) and temperature controls.
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