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PLANT HVAC SYSTEMS

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PLANT HVAC SYSTEMS

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  1. PLANT HVAC SYSTEMS DU-109-PP

  2. PLANT HVAC SYSTEMS • PURPOSE • The purpose of the Operations and Maintenance Training Program is to train Operations and Maintenance Technicians in the operation of the Duke University Plant Heating, Ventilation, and Air Conditioning (HVAC) Systems. • OBJECTIVES • Trainees will demonstrate knowledge of • HVAC System Components • HVAC System Components Operation • HVAC System Configuration • HVAC System Controls and Instrumentation

  3. PLANT HVAC SYSTEMS • PURPOSE • The purpose of the Heating, Ventilation, and Air Conditioning (HVAC) System is to: • Provide heat and cooling climate control for plant, office/control room, and electrical room areas of the steam and chiller plants • Maintain Interior Air Quality (IAQ) • Maintain air pressure • Provide emergency exhaust

  4. PLANT HVAC SYSTEMS • HVAC AIR FUNCTIONS • To understand how HVAC works, you need to be familiar with the six functions of HVAC air. • Return Air • Air inside the building drawn back into the air handlers • Outside Air • Fresh air drawn into the air handlers from outside • Supply Air • Air blown into the building from the air handlers

  5. PLANT HVAC SYSTEMS • HVAC AIR FUNCTIONS • Makeup Air • Air blown into the building by Makeup Air Unites (MAUs) to maintain air pressure balance when pressure is low • Relief Air • Air exhausted from the building to maintain air pressure balance when air pressure is high • Exhaust Air • Air expelled to remove contaminants from areas where chemicals, hazardous materials, and toxic gases are present • Air exhausted from the building in case of emergency

  6. PLANT HVAC SYSTEMS • WHY AIR BALANCE IS IMPORTANT • Over Pressure and Under Pressure conditions negatively affect building efficiency. • Over Pressure • When air pressure inside a building is higher than pressure outside, the conditioned air inside the building is pushed outside. • High air pressure can require excess energy to condition the air in the building and compensate for energy lost.

  7. PLANT HVAC SYSTEMS • WHY IS AIR BALANCE IMPORTANT? • Under Pressure • When building pressure is lower than pressure outside, the air outside is drawn inside. • Outside air may come from undesirable sources (trash bins, open doors, cracks, construction, and so forth). • Unfiltered or unconditioned air can affect the HVAC system’s ability to maintain the desired environment.

  8. PLANT HVAC SYSTEMS • QUESTION • What does IAQ stand for? • International Air Quality • Industrial Air Quality • Interior Air Quality • In-duct Air Quality

  9. PLANT HVAC SYSTEMS • ANSWER • IAQ stands for Interior Air Quality.

  10. PLANT HVAC SYSTEMS • QUESTION • What kind of air is blown into building from air handlers? • Return Air • Outside Air • Makeup Air • Supply Air

  11. PLANT HVAC SYSTEMS • ANSWER • Supply Air is recirculated through the air handlers.

  12. PLANT HVAC SYSTEMS • QUESTION • What kind of air is added when air pressure is low? • Return Air • Outside Air • Makeup Air • Supply Air

  13. PLANT HVAC SYSTEMS • ANSWER • Makeup Air is blown into a building when air pressure is low.

  14. PLANT HVAC SYSTEMS • QUESTION • What causes Over Pressure? • Pressure is higher on the lower level than on the mezzanine • Pressure is lower in the building than outside • Pressure is higher in the building than outside • Pressure is lower on the lower level than on the mezzanine

  15. PLANT HVAC SYSTEMS • ANSWER • Over Pressure is the condition when pressure inside the building is higher than outside.

  16. PLANT HVAC SYSTEMS • QUESTION • What causes Under Pressure? • Pressure is higher on the lower level than on the mezzanine • Pressure is lower in the building than outside • Pressure is higher in the building than outside • Pressure is lower on the lower level than on the mezzanine

  17. PLANT HVAC SYSTEMS • ANSWER • Under Pressure is the condition when pressure inside the building is lower than outside.

  18. PLANT HVAC SYSTEMS • PLANT HVAC COMPONENTS • Air Handler Units (AHUs) • Makeup Air Units (MAUs) • Fan Coil Units (FCUs) • Exhaust fans • Supply fans • Emergency exhaust fans

  19. PLANT HVAC SYSTEMS • AHU COMPONENTS • The Mixing Box section contains: • Return Air Damper which connects to the Return Air Duct • The Relief Air Damper also connects to the Return Air Duct • Outside Air Damper which connects to the duct to the building exterior RELIEF AIR DAMPER RETURN AIR DAMPER OUTSIDE AIR DAMPER MIXING BOX

  20. PLANT HVAC SYSTEMS • AHU COMPONENTS • The Filter section contains: • Access door for filter element replacement • W.C. Meter mounted in door • Filter is replaced when air pressure reaches maximum resistance RETURN AIR W.C. METER RELIEF AIR OUTSIDE AIR FILTER MIXING BOX

  21. PLANT HVAC SYSTEMS • AHU COMPONENTS • The Cooling Coil section contains: • In and Out connections for chilled water • Cooling coil heat exchanger RELIEF AIR RETURN AIR OUTSIDE AIR COOLING COIL FILTER MIXING BOX

  22. PLANT HVAC SYSTEMS • AHU COMPONENTS • The Heating Coil section contains: • In and Out connections for steam • Heating coil heat exchanger RETURN AIR RELIEF AIR COOLING COIL OUTSIDE AIR HEATING COIL FILTER MIXING BOX

  23. PLANT HVAC SYSTEMS • AHU COMPONENTS • The Fan section contains: • Fan and motor • Starter Box mounted on exterior or nearby RETURN AIR OUTSIDE AIR HEATING COIL COOLING COIL FILTER MIXING BOX

  24. PLANT HVAC SYSTEMS • QUESTION • What is accomplished in the AHU mixing box? • Return air is mixed with relief air • Supply air is mixed with return air • Supply air is mixed with outside air • Return air is mixed with outside air

  25. PLANT HVAC SYSTEMS • ANSWER • Return air is mixed with outside air in the AHU mixing box.

  26. PLANT HVAC SYSTEMS • QUESTION • What kind of meter is mounted in the filter section door of an AHU? • Temperature sensor • Pressure gauge • W.C. meter • Anemometer

  27. PLANT HVAC SYSTEMS • ANSWER • A W.C. meter is mounted in the door of the filter section. The W.C. (Water Column) meter measures resistance through the filter in inches to indicate when the filter needs to be changed.

  28. PLANT HVAC SYSTEMS • QUESTION • Where is the starter box located for an AHU? • Exterior of the fan section or nearby • Mixing box • Control Room • AHUs do not need starters

  29. PLANT HVAC SYSTEMS • ANSWER • The starter box is mounted on the fan section of the AHU or nearby.

  30. PLANT HVAC SYSTEMS • MAU COMPONENTS • The Fan section contains: • Fan and motor • Outside Air Damper which connects to the duct to the building exterior OUTSIDE AIR DAMPER FAN

  31. PLANT HVAC SYSTEMS • MAU COMPONENTS • The Coil section contains: • In and Out connections for steam and chilled water • Heating and cooling coil heat exchangers OUTSIDE AIR DAMPER HEATING COIL COOLING COIL FAN

  32. PLANT HVAC SYSTEMS • MAU COMPONENTS • The Filter section contains: • Filters • Supply Air Damper SUPPLY AIR DAMPER FILTER HEATING COIL OUTSIDE AIR DAMPER COOLING COIL FAN

  33. PLANT HVAC SYSTEMS • MAU COMPONENTS • The Starter box is located next to the MAU.

  34. PLANT HVAC SYSTEMS • QUESTION • What is one way an MAU differs from an AHU? • The MAU takes in return air and outside air • The MAU takes in relief air only • The MAU takes in outside air only • The MAU takes in return air only

  35. PLANT HVAC SYSTEMS • ANSWER • The MAU takes in outside air only.

  36. PLANT HVAC SYSTEMS • QUESTION • What does MAU stand for? • Main Air Unit • Maximum Air Unit • Mini Air Unit • Makeup Air Unit

  37. PLANT HVAC SYSTEMS • ANSWER • MAU stands for Makeup Air Unit.

  38. PLANT HVAC SYSTEMS • QUESTION • What is another way an MAU differs from an AHU? • The MAU has a mixing box • The MAU does not have a mixing box • The MAU has a cooling coil • The AHU has a cooling coil

  39. PLANT HVAC SYSTEMS • ANSWER • The MAU does not have a mixing box.

  40. PLANT HVAC SYSTEMS • FCU COMPONENTS • Outside Air Damper • Electric Duct Heater RETURN AIR SUPPLY AIR ELECTRIC DUCT HEATER OUTSIDE AIR DAMPER

  41. PLANT HVAC SYSTEMS • FCU COMPONENTS • Filter • Cooling Coil • Fan and Motor FAN COOLING COIL FILTER

  42. PLANT HVAC SYSTEMS • QUESTION • What does the FCU use to heat supply air? • Steam • Hot water • Electricity • Friction

  43. PLANT HVAC SYSTEMS • ANSWER • The FCU uses an Electric Duct Heater to heat air in the supply air duct.

  44. PLANT HVAC SYSTEMS • QUESTION • What does FCU stand for? • Forced Cooling Unit • Facilities Control Unit • Furnace Coil Unit • Fan Coil Unit

  45. PLANT HVAC SYSTEMS • ANSWER • FCU stands for Fan Coil Unit.

  46. PLANT HVAC SYSTEMS • PLANT HVAC SYSTEMS CONFIGURATION AND PROCESS FLOW • The flow for Chiller Plant #2 is used as an example.

  47. PLANT HVAC SYSTEMS LOCAL CONTROLLER DCS • CHILLER PLANT #2 AHU-21 SYSTEM • Temperature Transmitters on the Return Air Duct, Supply Air Duct, and Mixing Box of AHU-21 send readings to the Local Controller Digital Control System (DCS). RETURN AIR DUCT SUPPLY AIR DUCT MIXING BOX AHU-21

  48. PLANT HVAC SYSTEMS • CHILLER PLANT #2 AHU-21 SYSTEM • The local DCS controls heating and cooling by modulating the Cooling Coil chilled water control valve and the steam valve supplying the Heating Coil. LOCAL CONTROLLER DCS COOLING COIL HEATING COIL MIXING BOX CHILLED WATER CONTROL VALVE STEAM VALVE

  49. PLANT HVAC SYSTEMS • CHILLER PLANT #2 AHU-21 SYSTEM • The Outside Air Damper is set at 2,000 CFM. • The Return Air Damper is set at 30,000 CFM. SUPPLY AIR DAMPER D-21E AHU-21 MIXING BOX OUTSIDE AIR DAMPER D-21F

  50. PLANT HVAC SYSTEMS • CHILLER PLANT #2 AHU-21 SYSTEM • 1,000 CFM exhausted continuously from Chemical Treatment area by Exhaust Fan EF-23. • 350 CFM exhausted continuously from the Break Room, Men’s and Women’s Restrooms, Shower, and Janitor’s Closet by Exhaust Fan EF-24. BREAK ROOM JANITOR’S CLOSET SHOWER EXHAUST FAN EF-24 WOMEN’S RESTROOM EXHAUST TO OUTSIDE MEN’S RESTROOM LOUVER L-28