Module1 - Basics of HVAC

BASICS OF HVAC
Learning Objectives
1. HVAC Meaning.
2. Five goals every HVAC system tries to accomplish.
3. Describe the types of buildings and facilities where technicians work.
4. List the three primary methods of heating a room or facility.
5. The difference between natural ventilation and forced ventilation.
6. Four functions of an air conditioning system.
7. Goal of refrigeration systems.

Studies conducted by The American Society of Heating, Refrigerating and Air-
Conditioning Engineers, the technical society for the HVACR industry have
determined that on average, people working in an indoor environment are most
comfortable when the temperature stays within a few degrees of the range of 72
to 77 degrees Fahrenheit, depending on the season.
ASRHAE studies have also found that the indoor humidity and the air flow around
people must be controlled within a similarly narrow range to be considered
comfortable for most individuals. If the temperature is even a few degrees hotter
or colder than this allowable range, the humidity becomes a little too high, or the
air is contaminated with annoying odors, the level of discomfort rises quickly and
effectiveness at our jobs and other activities can be dramatically reduced. It is the
goal of mechanical services companies to make sure this comfort range is always
maintained in the narrow range satisfactory to their customers.
Meaning of HVACR
Building climate is determined by three functions:
Heating
Ventilation and
Air Conditioning,
Which are all closely interrelated. This discipline is often shortened to simply
HVAC, referring primarily to environment control for the comfort of occupants in
a building. The letter R, which stands for Refrigeration, is often included at the
end of this abbreviation.
Modern HVAC installations are sophisticated systems using complex electronic

controls, so controls are another important area that HVACR engineers need to
know.
HVACR System Goals
There may be a great deal of complexity surrounding systems the technician is

charged with fixing or maintaining, but the ultimate goal of these systems is easy
to understand. A properly functioning HVACR system will do the following:
1. Regulate temperature and humidity
2. Circulate appropriate volumes of fresh air
3. Filter contaminants from air
4. Be unobtrusive and quiet
5. Operate efficiently and economically
Starting at the “drawing board” where a system is first designed, continuing with
construction and installation of the designed system, and concluding with
ongoing maintenance needed to keep installations in peak operating condition.
Generally, these services can be classified into three functional areas:
DESIGN........................
Creating and planning out in graphic form a system for a particular purpose.
CONSTRUCTION ………..
Building and putting the designed system in place.
MAINTENANCE …………
Maintaining and keeping the system in good condition so it operates at

maximum efficiency.
Besides these functional areas, one can may elect to focus on different categories
of end users, such as
Residential,
Health care,
Education or government,
And also develop special capabilities with different types of equipment or
technology, like solar or geothermal systems, for example. The systems that may
be serviced can vary greatly due to such factors as age, construction, use,
occupancy, geographic area, and original design.
Heating, ventilation, and air conditioning operations may each be provided as
independent systems that are inter-connected or as combinations where all
functions are integrated in one or more pieces of equipment.
Where Mechanical Services Work
Service technicians normally work on HVACR systems that provide comfortable

indoor climates for people or perhaps stabilize environments for safe food
storage or efficient industrial processes. The types of environments they are
called to work in are as varied as the buildings and manufacturing processes
being supported. Depending on age, size and purpose for which the building is
used, technicians might find themselves working in an equipment room, on the
roof, in a walk-in freezer, or in the basement of a major facility.
The most common types of buildings and facilities where technicians work are:
 Commercial Buildings
 Industrial Processing Plants
 Manufacturing Plants
 Institutional Facilities
 Food and Retail Establishments

 Single and Multi-family Residences
Heating Systems
When the weather is cold outside, people want their indoor

room temperature to be warm and comfortable. Buildings may
use gas boilers, electric heating coils, or even geothermal
sources of heat, with water, steam, or air as the transfer
medium carrying heat as desired to different zones throughout
the building.
The system consists of piping and ductwork which takes the
heated fluid or forced heated air into different parts of the
building. Often the same piping or ducting may be used for
heating or air conditioning to add or remove heat from various
building zones people occupy. In typical commercial
installations, equipment for the heating system is usually
housed in a central mechanical room.
Ventilation
Ventilation simply refers to the changing of air in any space

to remove stale air, moisture, odors, smoke, heat, bacteria,
or other airborne contaminants. At home we simply open a
window to clear the air of unwanted smoke or odors. This is
referred to as natural ventilation because we are
ventilating a space without using a fan or other mechanical
system. However, because windows in most
Commercial buildings cannot be opened, a mechanical system, or forced
ventilation is used to control indoor air quality. Ventilation includes both the
exchange of air to the outside as well as circulation of air within the building.
Forced air that is carried through ductwork is usually filtered or sometimes put
through more elaborate air cleaners to keep it fresh and prevent irritating
particles or odors from entering the working environment.
Proper ventilation is one of the most important factors for maintaining
acceptable indoor air quality in buildings. Ventilation related equipment is often
distributed in the central mechanical room, on rooftops, and in the indoor zones
serving building occupants.
Air Conditioning
When the weather is too warm, occupants want their

indoor spaces to be cooler, and sometimes less humid
than the outside air. An air conditioning system provides
heating, cooling, ventilation, and humidity control for all or
part of a building. It does this by moving heat and
humidity taken from zones people occupy to someplace
outside the building environment. We often think of an air
conditioning system as being one that only cools an area.
On the contrary, air conditioning simply “conditions air” to
whatever temperature is required. Central air conditioning
systems are often installed in offices and public buildings.
Older buildings sometimes require a retrofit which means
new equipment or systems must be installed in a building
that was not designed to receive them. This equipment is
most often located on the rooftop or in a location outside
the building.
Refrigeration Systems
The goal of refrigeration is to cool a space or substance so

that it is below the environmental temperature.
Refrigeration systems are used chiefly to store food and
other perishables at low temperatures in order to prevent
bacteria, yeasts and molds from growing.
Technicians who work on these systems often cool spaces to
a temperature as low as minus 190 degrees Fahrenheit. In
addition to freezers and walk-in coolers used in restaurants
and other food service establishments, refrigeration
specialists may work on skating rinks, hockey arenas, food
production, or industrial processes that require lower
temperatures.

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BASICS OF HVAC

2. Five goals every HVAC system tries to accomplish.

3. Describe the types of buildings and facilities where technicians work.

4. List the three primary methods of heating a room or facility.

5. The difference between natural ventilation and forced ventilation.

6. Four functions of an air conditioning system.

7. Goal of refrigeration systems.

Building climate is determined by three functions:

Modern HVAC installations are sophisticated systems using complex electronic

There may be a great deal of complexity surrounding systems the technician is

1. Regulate temperature and humidity

2. Circulate appropriate volumes of fresh air

3. Filter contaminants from air

4. Be unobtrusive and quiet

5. Operate efficiently and economically

Building and putting the designed system in place.

Maintaining and keeping the system in good condition so it operates at

Where Mechanical Services Work

Service technicians normally work on HVACR systems that provide comfortable

 Industrial Processing Plants

 Food and Retail Establishments

When the weather is cold outside, people want their indoor

Ventilation simply refers to the changing of air in any space

When the weather is too warm, occupants want their

The goal of refrigeration is to cool a space or substance so

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