BATMAN
What are the three direct ways the human body gives off heat?
Conduction, Convection and Radiation
: What is it called when fresh air is introduced through an air handling system?
Fresh Air Intake or Ventilation
What chart can be used to determine comfortable temperature and humidity combinations?
The Generalized Comfort Chart
What is a drive clip used for?
Connecting trunk duct or plenum sections.
: What is the standard atmospheric pressure?
14.696 psi.
How can you simply check if air is flowing from a register?
By feeling for airflow 2–3 ft away from the register.
What is a reason to use an extended plenum system?
To bring the plenum closer to far supply registers.
Why are dampers used in branch ducts?
To balance airflow to individual areas.
What is a drawback of an extended plenum system?
Air velocity decreases toward the end of the plenum.
What is the purpose of a supply duct system?
To distribute air to terminal units, registers, and diffusers.
What is water in the form of low-pressure vapor suspended in the air called?
Humidity
What is the fourth way the human body gives off heat besides conduction, convection, and radiation?
Evaporation of Perspiration
Can friction in ductwork be eliminated?
No, but it can be minimized by good design practices.
What does a manometer measure in a duct system?
The velocity pressure of moving air.
What instrument is commonly used to measure airflow speed in ducts?
An anemometer or velometer.
How is a pitot tube constructed and used?
It has two concentric tubes bent at 90°, with the open end facing into the air stream.
What unit is used to measure airflow pressure in ductwork?
Inches of water column (in. WC).
What is an example of a natural-draft heating system?
Baseboard hot water heat.
What is the dew-point temperature?
The temperature at which moisture begins to condense out of the air.
How can you lower heating costs in the winter?
Raise the humidity level and lower the thermostat setting.
How does air movement improve comfort?
By increasing moisture evaporation from the skin and reducing the effects of high humidity.
How is humidity measured in the air?
By weight, in pounds or grains.
What components make up a forced-air system?
Blower (fan), air supply system, return air system, and grilles/registers.
How does a forced-air system differ from a natural-draft system?
A forced-air system uses a blower, while a natural-draft system relies on natural air movement.
What is friction loss in a duct system?
The resistance to airflow per foot of duct.