HVAC Design Fundamentals (PART 1 OF 5)

Design HVAC systems by following building survey, load calculations, and system and equipment selection, while coordinating with architects and contractors using BIM for effective design and installation.

Learn hvac drawing types from concept (tender) to as-built, including design, base, detail, shop, and installation drawings, with cross-disciplinary coordination.

Outline hvac installation from design drawings, tender drawings and IFC to scale drawings by subcontractors, followed by installation, tab, qc, and final drawings for maintenance.

Understand heat as a form of energy and its transfer via conduction, convection, and radiation, and learn BTU, temperature scales, sensible and latent heat, vapor compression cycle, and load calculation.

Explore conduction, convection, and radiation as foundational heat transfer modes and apply them to load calculations, heat gain through walls, ventilation, and glass, including mixed-mode effects.

Explore the concept that temperature measures the intensity of thermal activity and molecular motion, and learn how temperature scales (Fahrenheit, Celsius, Kelvin) and their conversions govern heat transfer.

One ton of refrigeration is the cooling effect from melting 1000 kg of ice in 24 hours, equal to 12,000 btu per hour and latent heat of ice 335 kj/kg.

Explore sensible and latent heat and heat gain sources such as walls. Learn q = m cp Δt for sensible heat and q = m L for latent heat.

Explore the importance of units and the international system of units, metric, and imperial, and master practical conversions for hvac design, estimation, and on-site application.

Describe the thumb rule for cooling as a quick initial calculation, noting that one ton covers 100 ft² (3 m height), with insulation and green-building considerations.

Define pressure as force per unit area and relate it to hvac applications, including static, dynamic, and total pressure, the second law, refrigerants, and the vapor compression cycle.

Explore the zeroth and first laws of thermodynamics and, crucially for hvac design, the second law guiding heat transfer and system selection by season.

Explore refrigerants as the heat carrying medium in the vapor compression cycle—absorbing heat at the evaporator and rejecting it at the condenser, with examples like R134a and R410a.

Understand the vapor compression refrigeration cycle, its four core components—compressor, condenser, expansion device, evaporator—and how high and low side pressures enable heat transfer and phase changes.

Explore dry bulb and wet bulb temperatures, dew point, and humidity to perform psychrometric analysis with charts or software, enabling accurate HVAC load calculations.

Dew point temperature is the temperature at which water condenses from air onto surfaces, not fixed but varying with air properties and shown on the psychrometric chart.

Learn the key humidity concepts for hvac design—humidity ratio, relative humidity, and enthalpy—and how saturation, units, and psychrometric relations guide comfort and load calculations.

Learn to use the psychrometric chart to derive humidity ratio, dew point, RH, and enthalpy from known properties such as dry bulb and wet bulb. Compare manual charts and software.

Explore the psychrometric heating process on the psychometric chart, focusing on sensible heating, humidity ratio, and relative humidity for load calculations and future equations for sensible, latent, and total heat.

Explore cooling with a coil using chilled water or refrigerant, delivering sensible plus latent cooling as moisture condenses, affecting dew point and relative humidity, guided by the psychrometric chart.

Learn the dehumidification process in hvac design by cooling air then reheating to maintain 75°F at 50% rh, using overcooling and condenser waste heat with a two-coil system.

Explore isothermal humidification, maintaining temperature while adding moisture via steam or heated water, and adiabatic humidification, increasing humidity without heat input through a wet medium, humidity ratio and enthalpy concepts.

Describe the evaporative cooling process in air coolers or desert coolers, where dry-bulb temperature drops while enthalpy stays constant, and humidity rises without condensation, reflecting only sensible cooling.

Analyze the mixed air process by combining outdoor and return air at key ratios to determine mixing temperature, dew point, and humidity, noting fresh air standards and cooling coil load.

Explore three core heat equations for sensible, latent, and total heat in HVAC load calculations, using CFM, delta t, delta w, and delta h with density and specific heat details.

Classify air conditioning systems by application, design, technology, and compressor type. Review common configurations from window and split units to VRF, chillers, district cooling, and radiant cooling.

Explore how window air conditioners apply the vapor compression cycle with four components to cool small spaces. Assess the plug-and-play design and key tradeoffs like noise and limited capacity.

Explore split air conditioning systems, indoor and outdoor units, FCU concepts, and common indoor types (high wall, cassette, tower), while understanding noise reduction and zone (thermostat) concepts.

Learn about split system components and refrigerant flow: outdoor condenser, indoor evaporator, liquid and suction lines with flow from outdoor to indoor, line sizes, drain piping and u-trap.

Explore split system configurations—high-wall, cassette, and tower options—covering suction and liquid lines, insulation, drainage, power supply, installation, refrigerants, and system pressures.

Explore the ducted split concept within central air conditioning, showing how a larger outdoor–indoor unit uses ductwork to supply air to multiple spaces with fresh air, drainage, and insulation.

Compare air cooled and water cooled package systems, detailing condenser types, shell and tube heat exchangers, cooling towers, rooftop package units, and integrated supply and return ducting.

Explore vrf and vrv systems under direct expansion. See how a single outdoor unit serves multiple indoors of different types with inverter or digital scroll compressors and vfd.

Explore cooling only VRF, heat pump, and heat recovery VRF systems, detailing cooling and heating options, three-pipe configurations, and the role of inverter scroll compressors and electronic expansion valves.

Explore how a heat pump vrf uses a reversed vapor compression cycle for cooling or heating, controlled by a four-way reversing valve, with outdoor condenser and indoor evaporators.

Explore heat recovery VRF systems with a three-pipe network for cooling, heating, or both. Illustrate how waste energy is redistributed between spaces, supported by BMS integration and precise valve control.

Explore fan coil units and air handling units as localized cooling and heating solutions, classifying FCU types—from concealed to cassette and ducted—across refrigerant, chilled water, and VRF systems.

Explore the air handling unit as the central HVAC component that conditions and distributes supply and return air, detailing AHU types and configurations.

Explore various ahu types, including modular and fresh air handling units, detailing supply, return, exhaust, and fresh air flows, and explain heat recovery configurations and energy-saving benefits.

Explore chillers as a complete chilled water system, including air cooled and water cooled package chillers, compressor types, district cooling, and vapor compression and absorption cycles, plus shell-and-tube evaporators.

Explain shell and tube heat exchangers for evaporators and condensers, and contrast air cooled and water cooled chillers, detailing chilled water cycles and primary/secondary loops.

Explain water cooled chiller operation, including two shell and tube exchangers, three cycles (refrigerant, chilled water, condenser water), insulation needs, and cooling tower integration.

Compare direct expansion and chilled water systems, including district and radiant cooling, under the essential water system; assess efficiency, cost, and installation considerations for various applications.

discover the district cooling system, a centralized chilled water network where a district cooling plant and absorption chillers supply insulated pipelines to multiple buildings, with BTU meters for energy-based billing.

Radiant cooling circulates water through panels under floors or walls to transfer heat by radiation, lowering the mean radiant temperature and reducing energy consumption.

Explore all-air conditioning concepts, including constant air volume vs variable air volume systems, CV vs VAV zoning, and dual duct configurations, along with their control strategies and practical applications.