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HVAC Basics

HVAC Basics

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HVAC Basics

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  1. HVAC Basics The Basics of Heating, Ventilation and Air Conditioning Presented by: Mark Kartchner, PE, LEED Kartchner Engineering

  2. Energy Use – Office Buildings

  3. Mechanical System Costs First Cost - Water cooled chillers beat Air cooled chillers at about 200 Tons (80,000 SF) SEL HQ VAV-$10.5/SF, FP-$1.9/SF, Plumb-$3.4/SF 90,000 SF CWC $12.5/SF WSHP & $3.5/SF Plumb 90,000 SF

  4. HVAC Rules of Thumb Air - 1 CFM/SF Cooling (office) – 300/400 SF/Ton Cooling (office) 400 CFM/Ton Heating 25-35 btuh/sf floor area Outside Air – 20 CFM/person Toilet/Jan Closet – 10 air changes/hour

  5. HVAC Equipment/SF Mechanical Room (Boilers/Chillers/Pumps/Misc) = GU College Hall = 2000 SF/186,000 = 1.1% Mechanical Room (Boilers/Pumps/Misc) = RTF (tight) – 300 SF/28,000 SF = 1.1% Colbert Elementary – 312 SF/ 40,000 SF = 0.8% RTU (Gas/Electric/VAV) = SEL Office (35’x12’ (2))/95,000 SF

  6. Building Envelope

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

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

  9. Actual R-Values

  10. Window Types

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

  12. Window Properties Energy Calculations in the Spokane region show that reflective, and tinted windows increase energy usage on an annual basis.

  13. 􀁺 Air Side Economizers 􀁺 Water Side Economizers 􀁺 Variable Frequency Drives 􀁺 Building Diversity 􀁺 Part Load Performance 􀁺 Thermal Storage 􀁺 Heat/Energy Recovery Energy Saving Design Methods

  14. Heating, Ventilation and Air Conditioning Provides comfortfor people Allows humans to exist under adverse conditions. HVAC SYSTEMS

  15. Basic Refrigeration Cycle

  16. Packaged Rooftop Unit Split System Air to Air Heat Pump Water Source Heat Pump Geothermal VAV Variable Air Volume Under Floor Air Distribution (UFAD) Air to Air Hydronic (water) PTAC / PTHP System Types

  17. Packaged Rooftop Units (RTU)

  18. Split System

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

  20. Water Source Heat Pump

  21. Geothermal Heat Pump Systems

  22. (VAV) Variable Air Volume

  23. Variable volume: Parallel VAV Terminal Units Constant volume: Series

  24. Under Floor Air Distribution (UFAD) Advantages Individual Controllability Re-Configurability 2 Extra LEED Points Disadvantages More Expensive ($8/SF for raised floor) Flexible for Change 2 Extra LEED Points Inland Power & Light First UFAD in area

  25. Four Pipe Fan Coil VAV w/ HW Reheat Hydronic systems

  26. Chillers Boilers Cooling Towers Hydronic System Major Equipment

  27. Chilled Water System

  28. Economizers Air Side Water Side

  29. Free cooling source: When available, use cool outdoor air instead of mechanically cooled air. Economizers Minimum supply of outside air 55 oF and up 55 oF 85% outside air 85% exhaust 80 oF 80 oF 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 HVAC-29

  30. Enthalpy Wheels

  31. Grilles, Registers Many options GU Russell Theatre Return Grille Return Plenum Extra cost for plenum rated cable is less than cost of return ductwork No Combustables Air Distribution

  32. Outside Air Louvers • Outside Air Louvers provide an opening in a building wall to push air out, or pull air in. • Provide clean outdoor air, avoid: • loading docks • exhaust vents • plumbing stacks • waste collection • stagnant water

  33. Square Ductwork Most common Low height Round Ductwork Less Expensive Easy to Install Lower static pressure Taller than Rectangular Higher pressure Less Sound Oval Ductwork Same advantages of round Height similar to rectangular More expensive than rectangular Metal Ducts

  34. Great for certain applications Gyms Pools Manufacturing Spokane Science Museum Advantages Great Diffusion Easily Cleaned Fun Same cost as metal Fabric Ducts Saved $300,000 in cost at high school. Lowered chilled water temp, & air temperatures

  35. Heat Exchangers Humidifiers Silencers Additional Equipment

  36. Kitchen Hoods • Type 1: Hoods designed for grease exhaust applications • Type 2: Hoods designed for heat and steam removal and other non grease applications. (NFPA 96 does not cover) • Where are Type 1 Commercial Hoods Required? • NFPA 96 “Cooking equipment used in processes producing smoke and grease-laden vapors shall be equipped with…” • NPFA 96-A-1-1 “…intended to include residential cooking equipment where used for purposes other than residential family use” • Type 1 Hood Clearances • 18 inches to combustible material • 3 inches to limited-combustible material • 0 inches to noncombustible material A restaurant with a commercial gas range is represented by the resteaurant owner to be used ony for the preparation of soups. What type hood is required? Type 1 hood is for collection and removal of grease laden vapors,and smoke. Type II hood is for removal of steam, odors, and vapors. It would be hard pressed to find a restaurant that only produces soups, with that commercial range. Hoods: where required, installed at or above all commercial-type deep fat fryers, broilers, fry grills, steam-jacketed kettles, hot-top ranges, ovens, barbeques, rotisseries, dishwashing machines, and similar equipment that produces comparable amounts of steam, smoke, grease, or heat in a food processing establishment. Food processing establishment shall include any building or portion used for the processing of food. Soup is a liquid food made up of simmering vegetables, seasonings, and often meat or fish. It is the potential of the equipment (Commercial gas range), rather than the utilization, that must be evaluated. So, what type of hood would be required for that commercial gas range in a restaurant would honestly be open for discussion. You will probably have some input from your local Fire Dept. through plan check as with the County Health dept. Requirements. I know of one City close to us that when a pizza parlor opens, no matter what, they require a type 1 hood. Depending on the type of pizza oven, we have allowed a type II.

  37. Kitchen Hood Types • Exhaust Hood w/ Supply Air Supplied by Space • Exhaust Hood w/Supply Air on Outside of Hood • Exhaust Hood w/Supply Air on Inside of Hood • Vapor Hoods • Simple hoods designed to remove minimal heat, and high vapor.

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

  39. ASHRAE Comfort Zone

  40. Psychrometrics • Dry bulb temp. • Wet bulb temp. • Humidity • Dew point • Moisture content • Heating • Cooling • Humidify • De-Humidify

  41. Historical Minimum Ventilation Rates (cfm/person) Smoking 62-89 Flugge 1905 Billings 1895 Nightengale 1865 Smoking 62-81 ASH- RAE 62-89 ASHRAE 62-73 Tredgold 1836 Yaglou 1938 ASHRAE 62-81

  42. 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

  43. 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 Improved Ventilation Effectiveness

  44. Acoustics

  45. Octave Band

  46. Directivity Factor