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CNST 2321 || with 100% Error-free Answers.
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What are the methods of control for air systems correct answers 1. Varying the temperature of the air supplied while holding the flow constant 2. Varying the flow of warm or cold air supplied while holding the temperature constant ng both the temperature and the flow of air supplied or turning th...

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  • August 4, 2024
  • 9
  • 2024/2025
  • Exam (elaborations)
  • Questions & answers

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  • what are the methods of control for air systems

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  • CNST 2321
  • CNST 2321

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CNST 2321 || with 100% Error-free Answers.
What are the methods of control for air systems correct answers 1. Varying the temperature of
the air supplied while holding the flow constant
2. Varying the flow of warm or cold air supplied while holding the temperature constant
3.varying both the temperature and the flow of air supplied or turning the system on or off

Multi Zone VAV systems are correct answers 1 used extensively in commercial buildings
2 have pot
3 least f

The actuated assembly is _____ _____ if flow is prevented when the control pressure (or other
signal) is absent correct answers Normally closed

All HVAC systems require some form of control to accomplish their task of controlling one or
more of the following properties correct answers 1. Temperature
2. Pressure
3. Flow rate
4. Humidity
5. Speed (fixed or variable)
6. Time

In HVAC terminology, a zone is an area where temperature is controlled by a single thermostat
correct answers True

The tendency of an assembly to conduct heat (U-factor) or heat transfer is directly proportional
to R and inversely proportional to U correct answers False

What are the three conditions that affect heating and air conditioning loads from introduction of
outside air? correct answers 1. Infiltration
2. Ventilation
3. Conduction

Energy codes recommend a maximum winter indoor design temperature of ____ and a minimum
summer indoor design temperature of ____. correct answers 72°F / 75°F

Comfort for building occupants is affected by a number of environmental variables, including the
following: correct answers 1. Temperature
2. Airflow
3. Humidity
4. Radiation

Dew point is when the humidity level reaches 75% at a given temperature correct answers False
(100%)

, Absolute humidity correct answers The amount of water in the air (measured in grains or pounds
of water per pound of dry air):

Two basic properties of air-water mixtures are: correct answers Temperature and humidity

Heating and cooling the ventilation (outside) air requires considerable energy, which is wasted
unless the energy is recovered from the exhaust air correct answers True

According ASHRAE, boilers and furnaces which condense flue gas in second heat exchangers
generally have annual fuel utilization efficiency (AFUE) in what range? correct answers 92% to
98.5%

List the four components of the vapor compression cycle in order correct answers 1) compressor
2) condenser
3) expansion valve
4) evaporator

If refrigerant is used in the air conditioning coil (evaporator), refrigerant to air exchange, the
system is generally termed direct expansion (DX) correct answers True

Refrigerants transfer heat (cooling) by changing phase from solid to vapor correct answers False
(Liquid to vapor)

What are the three circuits in a chilled water system? correct answers 1) refrigerant
2) chilled water circuit
3) condenser circuit

Which heat recovery system (ERU) will result in the highest cooling savings? correct answers
Enthalpy wheel

Which of the following statements are true regarding DX systems? correct answers 1) they
include roof top units and PTAC units
2) they can have condensers remote from the fan coil unit
3) refrigerant is used in the air conditioning coil (evaporator)

What are normal materials of construction for coils? correct answers Copper tubes and aluminum
fins

Which is the normal flow in a heating coil? correct answers Counter flow, which is water in on
the leaving air side

What is the unit of measure for water pressure in a pipe? correct answers Psi

What is the unit of measure for water velocity in a pipe? correct answers 1. Gpm
2. Ft/sec

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