Transcript BASICS OF SURVEYING

BASICS OF
HVAC
Ivy Tech Community College
Definitions – Page 862
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HVAC systems are made up of the
mechanical equipment such as the
furnace, air conditioner, and ductwork.
The duct is generally sheet metal pipe.
Types of duct include, cylindrical, oval,
rectangular and square.
Central Forced Air-Systems Page 862
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Central Forced Air Systems – are the most common
systems for heating and air-conditioning. They circulate
air form the living spaces through or around heating or
cooling devices.
A Thermostat starts the cycle as a fan forces the air into the
ducts. These ducts connect to openings called diffusers or
air supply registers which put warm air or cold air into the
room. If cool air is required, the return air is passed over
the surface of a cooling coil. If warm air is required the
return air is passed over the surface of a combustion
chamber (gas) or heating coil (electric).
Heat Pump - Page 864
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The heat pump is forced air central heating and cooling
that operates using a compressor and a circulating liquid
gas refrigerant. Heat is extracted from the outside air and
pumped inside the structure. The heat pump supplies up to
3x as much heat per year for the same electric
consumption. It works best when outside air is greater
than 20degF. In the summer the cycle is reversed and the
unit operates as an air conditioner.
Figure 25.6 shows how a heat pump works. What happens
when outside coils freeze over?
HVAC Drawings
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Drawings for HVAC systems show the size and
location of all equipment, ductwork and
components with accurate symbols, specifications,
notes, and schedules.
Symbols page 866. Note: ceiling supply outlet,
floor supply outlet, wall supply outlet, direction of
flow, and manual volume damper.
How does the foundation of a building affect the
decision to place floor, wall or ceiling outlets?
HVAC Drawings
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- Page 868
Draw duct runs using thick .03 mm line widths.
Label duct sizes when appropriate.
Duct sizes can be noted as 22 X 12 for example.
The first number 22 is the duct width and the
second number 12 is the duct depth.
Place notes on the drawings to avoid crowding.
Use aligned techniques.
Refer to schedules to get specific drawing
information not the the sketch.
Label equipment either block out or bold to stand
out from other information on the drawing.
Single and Double Line
Single line drawings are easier and faster to
draw. Refer to Figure 25.11
 Double Line drawings are often necessary
when complex systems require more detail.
Refer to Figure 25.12
 Your assignment is a double line drawing.
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Duct Specifications. – Page 871
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You will need to use reducers in your
drawing. Your supply ductwork is 14”
wide and is 10’ Long. The ductwork
leading to the vents is 6” Long. L = D1-D2.
(14”-6”=8”) Therefore your reducer Length
should be 8” Long.
Duct Legend – Page 872.
Drawing Tips:
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Note the Double Line Volume Damper. A
VD will be required in the drawing to dial
in each vents flow.
Drawing Tips:
You can use Flex Duct or Round Duct to
connect to your supply and return duct.
 Figure 25.16 is a good sample drawing.
 Use a leader line to show the CFM value
and Vent Size. – Refer to Duct Legend Page
872
 Show reducers as appropriate.
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