Heating, Ventilation, Air Conditioning and Refrigeration Fundamentals
HVAC basics
Understand the refrigeration cycle: compression, condensation, expansion, and evaporation. Refrigerant absorbs heat when evaporating at low pressure and releases it when condensing at high pressure. Know the roles of the compressor, condenser, metering device, and evaporator, and why superheat and subcooling matter for correct charge. Refrigerants are controlled substances - recovery, no venting, and correct handling are legal requirements.
Heating and ventilation
Heating systems include hydronic (boilers, radiators, underfloor), gas ducted, and heat pumps. Hydronic systems need correct pipe sizing, air removal, expansion provision, and controls. Ventilation covers natural and mechanical systems, duct sizing, pressure, and the importance of balanced supply and exhaust. Understand condensate management for high-efficiency appliances and the risk of trapped or frozen drains.
Plumbing interfaces
Plumbers interface with HVAC on condensate drainage, flueing, water connections to boilers and heat pumps, and gas supply to heaters. Condensate must discharge to an appropriate point, often via a trap, and must not create a cross-connection. Ductwork and pipework need insulation and support; air in hydronic lines causes noise and poor performance.
Traps and a worked rule
Traps: confusing the evaporator (absorbs heat) with the condenser (rejects heat); forgetting that condensate is a by-product needing drainage; and assuming any refrigerant can be topped up without checking type. Rule of thumb: in the cycle, the evaporator is where heat is picked up and the condenser where it is given away - trace the refrigerant, not the air. For hydronics, always provide air removal and expansion; sealed systems without them fail.