HVAC Machines Performance Evaluation and Selection

Examine the three indoor air impurities—particulates, microbes, and gases—and learn how air filters remove contaminants to protect air quality in HVAC systems.

Explore various air filter types including HEPA, carbon media, bag filters, ozone, and ultraviolet filters, with notes on efficiency, contaminants, airflow impact, maintenance, and safety considerations.

Use a simple impurity chart to select air filters, marking them effective, not effective, or partially effective; HEPA works for small particles, ozone and UV for whiteness.

Learn how air terminals regulate primary air from the central handling unit to occupied spaces. Explore types, placements, diffusers, grills, registers, and perforated panels, including air changes per hour.

Locate air terminals to optimize aspiration and mixing of primary and secondary air, achieving a high aspiration ratio for better room airflow in cold climates.

Design air terminals using the Q = 28 B formula and manufacturer catalogs, determining flow, diffuser size, neck area, and noise criteria for residential and office spaces.

Select air terminals using a guide to achieve fully mixed, partially mixed, or fully stratified airflow; compare ceiling versus wall mounting, adjustable versus fixed blades, and round or square diffusers.

Learn how air handling units control temperature, humidity, and oxygen, deliver conditioned air and fresh air as needed, and include components such as fans, filters, cooling, heat coils, and humidifiers.

Classify air handling units by arrangement—horizontal, vertical, drop-through, blow-through—and by location as rooftop or indoor; note single-zone and multi-zone, plus factory fabricated versus custom built AHUs.

Understand the components and construction of an AHU, including the double-wall body and insulation, dampers, filtration (MERV 6 minimum), cooling and heating coils, preheat and reheats, humidifiers, and energy recovery.

Design the AHU u-trap to prevent backflow of gas, water, and insects in the drain line, using the u-shaped section and prescribed clearances, with fan on/off pressures guiding dimensions.

Understand the fan coil unit (FCU), its fan and coil, and how it cools or heats indoor air as it passes over the coil, with filtration and minimal duct work.

Explore FCU classifications, including ceiling, wall, and floor mounted units, and compare two-pipe and four-pipe FCUs, showing how coil configurations enable heating, cooling, or zone-specific operation.

Explore how a two-pipe fcu heats or cools spaces by circulating hot or chilled water through coils, controlled by a mixing valve and thermostat.

Distinguish two-pipe FCU and four-pipe FCU by examining pros and cons, suitability for apartments, hotels, campuses, and large facilities, and the ability to simultaneously cool and heat across zones.

Discover how compressors raise refrigerant pressure in a closed system, and explore reciprocating, scroll, screw, centrifugal, and direct-driven variations with their advantages and typical applications.

Explore condenser fundamentals as a heat exchanger that rejects refrigerant heat, and compare air cooled, water cooled, shell-and-tube, and evaporative condensers, including design variants and efficiency considerations.

Explore the operating principles of cooling towers, including natural, induced, cross-flow, and counter-flow designs, and learn how to perform cooling tower calculations for makeup water, losses, and efficiency.

Compare evaporator types and their operation as heat exchangers in refrigeration: direct expansion and flooded evaporators absorb heat from air, water, or brine to evaporate refrigerant, connected to various compressors.