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BASICS OF HVAC Ivy Tech Community College Definitions Page 862 HVAC systems are made up of the mechanical equipment such as the furnace, air conditioner, and ... – PowerPoint PPT presentation

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  • Ivy Tech Community College

Definitions Page 862
  • 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
  • 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
  • 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
  • Figure 25.6 shows how a heat pump works. What
    happens when outside coils freeze over?

HVAC Drawings
  • 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 - 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.

Duct Specifications. Page 871
  • 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. (14-68) Therefore your reducer
    Length should be 8 Long.

Duct Legend Page 872. Drawing Tips
  • Note the Double Line Volume Damper. A VD will be
    required in the drawing to dial in each vents

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.