HVAC Systems Flashcards

Flashcards reviewing key concepts of HVAC systems including ventilation, air conditioning, system types, and design considerations, based on lecture notes.

How are ventilation requirements typically specified?

Requirements are usually given as a function of occupancy density in L/(s.pers) or air changes per hour.

What are the three types of mechanical ventilation systems?

Extract, Supply, and Balanced.

Where are extract systems most useful and what type of pressure do they create?

Useful near a source of contamination; creates negative pressure.

What do supply ventilation systems do and where are they useful?

Bring in filtered outside air; create positive pressure; useful where dust entry should be prevented.

What characterizes balanced ventilation systems?

Have both supply and exhaust provided by mechanical means; offer great control but are expensive.

What are the two main types of fans used in ventilation systems?

Propeller or axial flow and Centrifugal or radial flow.

How can sound attenuation be achieved in ducting?

Continuously lining the duct with sound-absorbing material or strategically locating sound attenuators/silencers.

What are the four types of air filters?

Dry filters, wet filters, air 'washers', and electrostatic filters.

What does 'air conditioning' now mean regarding total control?

Temperature, moisture in the air (humidity), supply of outside air for ventilation, filtration of airborne particles, and air movement in the occupied space.

What are the seven main processes required to achieve full air conditioning?

Heating, Cooling, Humidifying, Dehumidifying, Cleaning, Air Movement, and Ventilating.

How does an air conditioner work?

A thermodynamic machine that creates cold air on one end and hot air on the other end.

What are the types of HVAC systems?

Single-zone system, Multi-zone system, Constant volume system, VAV (Variable Air Volume) system, Heat pumps, Unit ventilator (fan coil).

What characterizes a single-zone HVAC system?

Serves a single, temperature-controlled zone; found in small shops or computer rooms.

What characterizes a Variable Air Volume (VAV) system?

System varies airflow, best way to zone large buildings.

What are the main groups of factors that influence the choice of an air-conditioning system?

Building design, Location issues, Utilities: availability and cost, Indoor requirements and loads.