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Facilities Management and Design. Chapter 7 HVAC Systems. Thermal Comfort. Balancing heat produced by one’s body with surrounding environment. Body heat lost by convection, radiation, and evaporation. Factors that influence comfort. indoor temperature humidity air movement
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Facilities Management and Design Chapter 7 HVAC Systems
Thermal Comfort • Balancing heat produced by one’s body with surrounding environment. • Body heat lost by convection, radiation, and evaporation
Factors that influence comfort • indoor temperature • humidity • air movement • room surface temperatures • overall air quality
Comfort zone • Insert comfort zone chart
Heat sources • Electricity– Used in all electric heaters. Requires no flue. Usually most expensive. • Natural gas – Clean burning. Flue required. Very efficient. Delivered via underground pipe • Liquefied petroleum – relatively clean burning. Requires on-site storage tank. Delivered via truck. • Fuel oil – tendency to create dirt/smoke. Requires on-site storage tank. Delivered via truck. Various grades available. • Steam – more common in urban areas where available from local utility or in large complexes with central steam plant. Supply and return lines required.
Heating equipment • Furnaces and Boilers • Combustion efficiency Flue Furnace Heat Exchanger
Cooling Systems • Boyles Ideal Gas Law • Pressure • Temperature • Volume • Certain gases react more actively • Refrigerants • CFC’s • HCFC’s
The Refrigeration Cycle Compressor Evaporator Coil Condenser Coil Expansion Valve/ Metering Device
Cooling system operating and maintenance concerns • Types of compressors • Reciprocating • Centrifugal • Rotary • Energy efficiency ratio (EER) • Integrated part load values (IPLV) • Environmental Protection Agency • supervises aspects of refrigeration equipment maintenance • importance of eliminating or reducing refrigerant leaks
Cooling system operating and maintenance concerns • Types of compressors • Reciprocating • Centrifugal • Rotary • Energy efficiency ratio (EER) • Integrated part load values (IPLV) • Environmental Protection Agency • supervises aspects of refrigeration equipment maintenance • importance of eliminating or reducing refrigerant leaks
HVAC system types • Centralized systems; quiet • two-pipe • three-pipe • four-pipe • Decentralized systems; not as quiet • heating and cooling sources in guestroom itself or along outside wall • Hybrid systems • characteristics of centralized and decentralized systems
System types and maintenance needs of HVAC systems for other building areas • Air handling units • Isolation of zones (housekeeping, kitchen, maintenance…) • Packaged air conditioning units • usually mounted on roof • Maintenance issues • Filter replacement • belt checking and replacement • cleaning of fans and heat transfer surfaces
HVAC controls • Today’s controls are often electronic • Thermostat • enthalpy or economizer control • Older control sensors—mechanical sensing • Digital control systems • variable air volume (VAV) systems • load sensing equipment • EMS sensors
Cooling towers • Startup and shutdown concerns • Inspection and lubrication of pumps and fans • Removal of dirt and other debris • Treatments to reduce bacteria, scale, and corrosion • Inspection of metal surfaces