HVAC systems provide the Fresh Air requirements for building occupants and make-up to replace air lost from a building from pressurisation or extract systems. In addition, they can provide both the heating and cooling function to offset building fabric and internal component losses or gains. Lastly, in some circumstances the HVAC systems are used to control humidity levels. However, not all HVAC systems are designed correctly or perform in accordance with their intended design.
There are several different types of refrigerant-based Air Conditioning (sometimes called air-con) systems installed in today's builings. From discrete systems with a sinlge indoor unit (evaporator or cassette) and a single outdoor unit (condenser). Next there are multiple indoor unit and single outdoor unit systems and lastly, multiple indoor and outdoor unit systems. Knowing which system to choose for which application can be a minefield. If the choice of the system is wrong or the selections of the components are mismatched the results can be disastrous resulting in high fuel bills and disgruntled building occupants.