Evidence shall show that knowledge has been acquired of safe working practices and designing heating, ventilation and air conditioning (HVAC) systems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EJ134A Commercial HVAC system design Evidence shall show an understanding of commercial HVAC system design, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects: T1. Design parameters for single-storey buildings (e.g. offices, restaurants, hotels, bars) Customer and objective Customer concept of environment desired Economics Client brief T2. Relevant design criteria Building purpose, location, orientation and shape External environment ambient conditions Internal load diversity Thermal capacity behaviour Thermal load (full and partial) T3. Zoning and building usage Space and building Occupancies, single purpose, multi-purpose T4. System selection criteria Economics Environment Control requirements Existing structures New structures System components Space for equipment and system Selection of appropriate system, equipment, ductwork and components T5. Systems and applications Design features, engineering and selection procedures for direct expansion air conditioning systems: RAC’s, split systems, package units Free blow and ducted fan coil units Cooling, heat pump and electric heating• KS02-EJ134A Air conditioning system components and piping selection Evidence shall show an understanding of air conditioning system components and piping selection, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects: T1. Relevant Standards, Codes Regulations and industry practices AS1677, detailed understanding AS 3666, overview ozone protection regulations ANSI/IIAR standards ANSI/ASHRAE Mechanical Refrigeration and IIAR bulletins and standards Equipment manufactures specifications and practices T2. Calculation of capacity in heat exchangers Q = UA (LMTD) Q = mc∆t Q = m ∆h T3. Evaporators commercial types and applications coil bypass factor effects of evaporator TD on space humidity effects of air circulation on product conditions selection criteria and selection tables T4. Condensers commercial types and applications effects of ambient conditions condenser control heat rejection factor condenser TD selection criteria and selection tables T5. Compressors types and applications capacity displacement volume flow rate theoretical capacity total volumetric efficiency effect of operating conditions, including suction pressure drop and superheating actual capacity power theoretical requirement effects of operating conditions actual requirements post defrost loads pull down torque requirements, high, medium and low back pressure compressors selection tables, motor selection T6. Liquid expansion devices types, operation and applications effects from sub-cooling distributor types, operation and applications selection tables System load balance point encompassing: graphical representation Line sizing an design velocity tables pressure drop in lines and fittings oil migration stabilisation refrigerant velocity effect of varying system capacity oil traps risers double risers liquid migration design for parallel components and multiplex systems T7. Automatic controls fin spacing, suction temp to evaporator suction hot-gas bypass valves electronic control of valves PLC control refrigerant regulating valves solenoid valves condenser pressure regulating valves evaporator pressure regulating valves crankcase pressure regulating valves cycling controls pressure-stats thermostats, defrost controls monitoring and alarm controls refrigeration automation systems control strategies control modes |