Chapter 32 Heating, Ventilation, and Air Conditioning
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Explain how heat travels through buildings. Identify ways to conserve energy in housing. Define AFUE and SEER ratings and list the appliances to which they are applied. List the characteristics of different central air conditioning systems. Objectives Slant/Fin Corp.
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Describe the functions of HVAC system components. Explain the design and operation of HVAC systems. Describe automatic controls for heating and cooling systems. Objectives (Cont.) Rheem Manufacturing Company
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Second Law of Thermodynamics states that heat always moves from hot to cold Heating and cooling of buildings depends on this principle Heat travels by three methods –Radiation –Conduction –Convection Heating and Cooling Principles
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Conservation Measures High-efficiency furnaces deliver more heat energy from fuel Heat exchangers in high- efficiency units extract more of heat of combustion Gases are exhausted to outside through small plastic pipe Carrier Corporation, subsidiary of United Technologies Group
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Energy Efficiency Ratings Manufacturers label heating and cooling appliances with energy efficiency ratings All furnaces sold in U.S. must have AFUE rating of at least 78% United States Federal Trade Commission
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Heating Systems Space heating uses heating devices in individual rooms Central heating uses single, large heating plant to produce heat Heat is then circulated throughout structure
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Air is circulated through large ducts Ducts direct warmed air to every room Furnaces may be oil-fired, gas-fired, or electric Registers are installed over duct openings in rooms Since warm air rises, registers are more efficient when located at floor level Forced-Air Perimeter System
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Forced-Air Perimeter Diagram
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Carbon monoxide is deadly gas created by incomplete combustion It has no odor HVAC specialist should test furnace for safe operation every year Most states have passed laws requiring carbon monoxide detectors in homes Safety Note
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Variation of forced-air system Used for basement area or for building with slab-on- grade construction Ductwork is installed before slab or basement floor is placed Ducts may be of sheet metal, concrete pipe, plastic pipe, or other precast forms Warm-Air Perimeter System
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Typical Warm-Air System
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Installation Installation of forced-air furnace usually follows installation of ductwork HVAC technician installs unit Same person may also install ductwork
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Hydronic Perimeter Heating System Uses water as medium to move heat from heating unit Boiler heats water much like teakettle sitting on burner Heated water is piped to radiators that transfer heat to rooms United Technologies Carrier
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Manifold Device in hydronic systems that balances delivery of heated water to different zones Consists of inlet pipe fitting with several outlets for connecting one pipe with others United Technologies Carrier
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. System Types In one-pipe system, single pipe (main) supplies heated water to room heating units Main also takes water back to boiler In two-pipe system, two mains are used –Supply main –Return main
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Piping is installed in structural part of building –On-grade over thick underlayment of rigid insulation –Under subflooring with insulation beneath heating tubes Hydronic Radiant Heating System
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Direct Heating Systems Heat source does not use ductwork or piping system to distribute heat –Stove or fireplace –Electric resistance baseboard heater –Electric radiant heat Slant/Fin Corp.
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Air Cooling Systems Move heated air from building to atmosphere May use same ductwork as heating system Cooled, liquid refrigerant is pumped through evaporator Refrigerant absorbs heat from air and evaporates
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Condenser Allows refrigerant to pass its heat to atmosphere In doing so, refrigerant returns to liquid state Refrigerant is pumped at high pressure to evaporator in furnace This completes one cycle
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Ducts Can be made of metal, rigid plastic, or flexible plastic Should be as unobtrusive as possible Most are prefabricated and then fitted and cut onsite
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Controls Thermostat can sense room temperature and send signals to unit Most thermostats are programmable They help save fuel costs by adjusting heating or cooling levels for different times Rheem Manufacturing Company
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Air Exchangers Indoor air should be exchanged with outdoor air every 2–3 hours Heat recovery ventilator uses heat in outgoing air to heat incoming fresh air During cooling season, HRV transfers incoming heat to outgoing stale air
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Energy Recovery Ventilator Performs same functions as HRV Also removes humidity from incoming air Helps maintain more comfortable humidity levels inside building RenewAire
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Combine heating and cooling in single unit Use refrigerant to collect heat from one place and deliver it to another location Efficiency drops as outside temperatures dip below 20°F (−5°C) Building may need auxiliary heating system Heat Pumps
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Heating Mode
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Cooling Mode
Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Construction Careers HVACR Installers Install and repair HVACR systems May specialize in one aspect of job Work for contractors or are self-employed Complete school training programs and apprenticeships lisafx/iStock/Thinkstock