NATE Air Distribution 3

Question 1

What is the purpose of a zone damper in a zoned HVAC system?

Accepted Answer

Open or close to direct conditioned air to specific zones based on thermostat demand

Answer

Zone dampers are motorized dampers controlled by zone thermostats that open to allow airflow to calling zones and close for non-calling zones.

Question 2

What type of duct fitting causes the most turbulence and pressure drop?

Accepted Answer

Square elbow without turning vanes

Answer

Sharp square elbows cause severe turbulence and high pressure drop; long-radius elbows or elbows with turning vanes greatly reduce this loss.

Question 3

What does the ASHRAE 62.2 standard address in residential applications?

Accepted Answer

Ventilation and acceptable indoor air quality for residential buildings

Answer

ASHRAE 62.2 specifies minimum mechanical ventilation rates to maintain acceptable indoor air quality in residences.

Question 4

What is a bypass damper used for in a zoned duct system?

Accepted Answer

Relieve excess static pressure when zone dampers close by routing air back to the return side

Answer

When zone dampers close, the bypass damper opens to maintain minimum airflow across the coil and prevent equipment damage from excessive static pressure.

Question 5

What is the correct method for measuring total external static pressure (TESP) on an air handler?

Accepted Answer

Measure static pressure in the return plenum before the coil and in the supply plenum after the coil, then subtract return from supply

Answer

TESP = supply static pressure minus return static pressure (both measured close to the air handler), giving total system resistance.

NATE - North American Technician Excellence Practice Test

NATE - North American Technician Excellence Practice Test

NATE Air Distribution 3