Heating, Ventilating, and Air-Conditioning

TABLE OF CONTENTS• Types of Systems• Central Forced Air System

– Air Handling Unit• Hot Water System• Zoned Control System• Radiant Heat• Heat Pump• HVAC Plans

Types of Systems

• Central Forced-Air Systems• Hot Water Systems• Zone Control Systems• Radiant Heat

Central Forced Air System

• Most Common HVAC System• Circulates air through or around heating

and cooling devices.• A fan forces air into ducts• Supply ducts transport conditioned air into

building through diffusers or supply registers

• Air is routed back to heating/cooling device through return ducts

Air Handling Unit (AHU)

• Device used to condition and circulate air as part of an HVAC system

• Large metal box containing a blower, heating or cooling elements, filter, and sound attenuators

• Connects to ductwork that distributes the conditioned air through the building and returns it to the AHU

Courtesy Eric Fisher

Air Handling Unit (AHU)

• May need to supply heating, cooling, or both• A furnace generates heat

– Fuel oil or natural gas– Electric heating elements– Heat pump

• A refrigeration system absorbs heat– Air conditioner– Heat pump

Air Handling Unit (AHU)• Smaller air handlers may contain a fuel-burning

heater or a refrigeration evaporator placed directly in the air stream

• Large commercial air handling units contain coils that circulate water– Boiler provides hot water or steam– Chiller provides chilled water

©iStockphoto.com ©iStockphoto.com

Wikimedia

1. Supply duct2. Fan compartment3. Flexible connection4. Heating and/or cooling coil5. Filter compartment6. Return and fresh air duct

Typical AHU components:

Air Handling Unit (AHU)

Hot Water System

• Water heated in boiler and circulated through pipes to radiators

• Requires plumbing rather than ductwork

©iStockphoto.com

Zone Control System

• One heater and one thermostat per room• No ductwork• Often used in hotel rooms

Radiant Heat• Supply heat directly to the floor, wall, or ceiling• Hot water pipes or electric heating element runs

through building component• Dependent on radiant heat

– Heat transferred from hot surface to people and objects

Wikimedia

Heat Pump (HP)• A machine or device that moves heat from one

location (the source) to another location (the mechanical work)

• Can produce heating or cooling by reversing the direction of heat flow

• Can be used in:– Forced Air System– Hot Water System– Radiant Heat System

wikimedia

HVAC Plans

Image Courtesy Novus Architects

HVAC (Mechanical) Plans

Image Courtesy Novus Architects

HVAC Mechanical Plans

Image Courtesy Novus Architects

TABLE OF CONTENTS• Types of Systems• Central Forced Air System

– Air Handling Unit• Hot Water System• Zoned Control System• Radiant Heat• Heat Pump• HVAC Plans

•en.wikimedia.org. Images retrieved Dec. 8, 2009.•Novus Architecture (formerly SGM Architects), Mt.

Pleasant, SC•www.istockphoto.com. Images retrieved Dec. 8, 2009.

Image Sources

Heating, Ventilating, and Air-Conditioning