HVAC Ductwork Systems Flashcards

What is the purpose of a 'smoke damper' and how does it differ from a fire damper?

Answer: A smoke damper is motor-operated and controlled by smoke detectors, while a fire damper uses a fusible link activated by heat

Smoke dampers are motor-operated and close upon signal from a smoke detection system. Fire dampers use fusible links that melt from heat. Combination fire/smoke dampers provide both functions.

What is the primary reason for insulating supply air ductwork?

Answer: To prevent heat gain or loss and control condensation on cold duct surfaces

Duct insulation prevents unwanted heat transfer between the conditioned air and the surrounding space, maintaining energy efficiency. It also prevents condensation from forming on cold duct surfaces.

What is an 'air handling unit' (AHU) and what components does it typically contain?

Answer: A factory-assembled unit containing fans, heating/cooling coils, filters, and dampers for conditioning and distributing air

An air handling unit is a comprehensive assembly that conditions air before distributing it through the duct system. It typically includes supply and return fans, heating and cooling coils, filters, mixing dampers, and controls.

What is the purpose of an 'economizer' in an HVAC system?

Answer: To use cool outdoor air for free cooling when outside conditions are favorable, reducing mechanical cooling load

An economizer uses dampers to introduce outside air when outdoor temperature and humidity are suitable for free cooling. This reduces the energy consumed by mechanical cooling equipment.

What is the code-required clearance between uninsulated HVAC ductwork and combustible materials?

Answer: A minimum of 1 inch clearance from combustible materials

Building codes generally require a minimum of 1 inch clearance between uninsulated supply ductwork and combustible construction. Greater clearances may be required for exhaust ducts or ducts carrying heated air.

What is the difference between a 'diffuser' and a 'register' in HVAC terminology?

Answer: A diffuser distributes air in a spreading pattern and typically has no damper, while a register has a built-in damper for flow adjustment

A diffuser is designed to spread supply air in a specific pattern across a room, typically mounted in ceilings. A register includes an integral damper allowing the occupant or technician to adjust airflow volume.