HVAC Commercial HVAC Systems 2

Question 1

What is the primary function of a cooling tower in a commercial HVAC system?

Accepted Answer

To reject heat from condenser water to the atmosphere

Answer

A cooling tower rejects heat absorbed by condenser water to the atmosphere through evaporative cooling.

Question 2

In a Variable Air Volume (VAV) system, what component controls airflow to each zone?

Accepted Answer

VAV terminal box with a damper

Answer

A VAV terminal box contains a motorized damper that modulates airflow to maintain the zone's setpoint temperature.

Question 3

What does the term 'tons of refrigeration' measure in commercial HVAC?

Accepted Answer

Heat removal capacity (1 ton = 12,000 BTU/hr)

Answer

One ton of refrigeration equals 12,000 BTU/hr of heat removal, derived from the heat needed to melt one ton of ice per day.

Question 4

Which refrigerant is most commonly used in modern large commercial chiller systems due to environmental regulations?

Accepted Answer

R-134a

Answer

R-134a is widely used in centrifugal chillers as it is an HFC with zero ozone depletion potential, compliant with modern regulations.

Question 5

What is 'economizer mode' in a commercial air handling unit?

Accepted Answer

Using outdoor air for free cooling when conditions are favorable

Answer

Economizer mode uses outdoor air instead of mechanical cooling when outside conditions (temperature/enthalpy) are suitable, reducing energy costs.

HVAC Practice Test