Discover Q&A generated by AI Answer Generator

In a single duct system with constant volume that has multizone capability, the device that must be added at the terminal units is:

D. Zone reheat

Zone reheat allows for temperature control in different zones by reheating the air delivered to those zones, accommodating varying heating needs while maintaining a constant volume of air flow.

To calculate the volume of air flowing through a duct, you need at least the following measurements:

A. Velocity pressure
D. Duct area

These two measurements allow you to determine the air velocity and then calculate the volumetric flow rate using the duct area. Air temperature and duct shape can be relevant for other calculations or considerations, but they are not necessary for calculating the volume flow rate directly.

To calculate the volume of air flowing through a duct, you need at least the following measurements:

A. Velocity pressure
D. Duct area

These two measurements allow you to determine the air velocity and then calculate the volume flow rate using the duct area. While air temperature and duct shape can influence other factors, they are not strictly necessary for calculating the volume

In a shell and tube heat exchanger used in a steam system, the correct configurations typically include:

A. Steam enters from the top - This is often the case to allow for proper drainage of condensate. C. Condensate leaves from the top - This is also common, as it allows for the condensate to be removed easily. E. Steam flows through the tubes - In many designs, steam is passed through the tubes, allowing heat transfer to the fluid in the shell.

So, the correct options are A, C, and E.

Options B, D, and F are generally not correct for a typical steam system configuration in a shell and tube heat exchanger.

Comfort problems will likely be experienced if zone temperature sensors are mounted in the following locations:

A. In direct sunlight
B. On an exterior wall
C. Behind an obstruction such as a door or bookcase

These locations can lead to inaccurate temperature readings, which can affect the heating and cooling system's performance and overall comfort in the space.

D. On an interior wall away from heat gains is generally a better location for a temperature sensor, as it is less likely to be influenced by external temperature fluctuations or obstructions.

D. Heat exchanger

C. Evaporative cooling of the skin.

When humidity is low, the moisture on the skin evaporates more quickly, which can lead to a cooling effect on the body. This can make people feel colder even if the air temperature is within a comfortable range.

The correct answer is D. State Point.

In the context of a Psychometric chart, a state point represents the specific condition of air at a given dry bulb temperature and wet bulb temperature, indicating its properties such as humidity and enthalpy.

The correct answer is:

C. Analog input

Zone temperature is a variable signal that can take on a range of values, which is characteristic of an analog input.

A. increases

Increasing the duct static pressure generally increases the volume of air delivered by a fan, as it allows the fan to push more air through the duct system. However, it's important to consider that there are limits to this effect, and other factors such as fan performance curves and system resistance also play a role.

A. TRUE

The temperature difference between the interior and exterior of a building can indeed affect building pressures. This phenomenon is often related to the principles of buoyancy and stack effect, where warmer air inside a building rises and creates a pressure difference that can influence air movement and ventilation. Additionally, temperature differences can lead to variations in air density, which can also impact pressure dynamics within the building.

A. TRUE

Damper authority refers to the ability of a damper to control the flow of air in a system, and it does contribute to the volume of mixed air flow in an air handler. Proper damper authority ensures that the desired amount of outside air and return air is mixed effectively to achieve the desired temperature and air quality.

Grills and louvres typically provide a free area for air of about B. 60-70%.

The fundamentals of air movement include:

A. Temperature
B. Pressure
C. Volume
D. Velocity

All of the options listed (A, B, C, and D) are relevant to the fundamentals of air movement. Temperature affects air density and pressure, pressure differences drive air movement, volume relates to the space that air occupies, and velocity describes the speed and direction of air movement.

B. FALSE

Air-cooled scroll chillers do not require a cooling tower, as they use air to dissipate heat. Cooling towers are typically used with water-cooled chillers, which rely on water to remove heat from the system.

A chiller is a specialized machine designed to remove A. BTUs (British Thermal Units) from a facility. It cools a fluid (usually water) that is then circulated to remove heat from the building or process.

The three anchors of the HVAC industry are typically considered to be:

A. Service
B. Systems
C. Controls

These three elements are fundamental to the operation and maintenance of HVAC systems. Installation (D) is also important, but it is often viewed as part of the broader category of systems. Environment (E) is relevant but not typically classified as one of the main anchors.

D. Latent Heat

While latent heat is a relevant concept in thermodynamics and heat transfer, it is not a specific term commonly used in psychrometry, which primarily focuses on the properties of moist air, such as relative humidity, humidity ratio, and dry bulb temperature.

The sources of added BTUs (British Thermal Units) in a building might include:

A. People
B. Lights
C. Sunshine through windows

D. Filing cabinets would not typically be considered a source of added BTUs, as they do not generate heat.

B. FALSE

Cooling towers are typically used in conjunction with water-cooled chillers, not air-cooled chillers. Air-cooled chillers use air to dissipate heat, while cooling towers are used to cool water that is circulated through water-cooled chillers.

The correct options are:

B. Lowered productivity
C. Occupant dissatisfaction

Keeping an office space too warm or too cold, or having the wrong humidity levels can negatively impact employee comfort and performance, leading to decreased productivity and dissatisfaction among occupants. Options A and D are not typically associated with improper temperature or humidity levels.

A device that measures the moisture content in the air is called a:

A. Hygrometer

While "humidimeter" is sometimes used, "hygrometer" is the more commonly accepted term.

The fundamentals of air movement include:

A. Temperature
B. Pressure
C. Volume
D. Velocity

All of the options listed (A, B, C, and D) are relevant to the fundamentals of air movement. Temperature affects air density and pressure, pressure differences drive air movement, volume relates to the space that air occupies, and velocity refers to the speed and direction of air

The measure of a change in temperature when a known amount of heat is applied is called:

B. Specific heat

Specific heat is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius (or one