There are many types of combined heating and ventilation system, with the ideal solution depending on your building and how you use it. One designed in hot Carolina may not be ideal in chilly Aberdeen, while a ducted system that is economical to install over a factory floor may not be so cheap if you run it through a listed building.
Choices are affected by fluctuations in the prices of gas, electricity and oil, and new legislation about refrigerant gases and energy efficiency. Here is a quick overview of four main options.
Heating and cooling split systems
This is probably the most common type and uses separate units for heating and cooling. The latter is usually situated outdoors and contains a fan, compressor and refrigerant gas coils. The heater unit is often installed in a basement if this is available. Air filters and humidifiers often supplement the two main units.
Split systems are easy to install and one system can often serve several apartments in a shared building or multiple offices.
Hybrid split systems
Hybrids are becoming more common because they help you to adapt to changing energy costs. They are usually designed to let you swap between gas and electricity and use whichever you choose more efficiently, reducing both the running costs and your environmental footprint.
At the heart of these systems is a hydro BC controller (HBC), which contains a heat exchanger between the outdoor refrigerant and pumped water that goes to the indoor unit. Having no refrigerant inside occupied spaces makes it easier to comply with refrigerant controls such as BS EN378. Cheap ductwork parts are easily connected and are available from suppliers such as https://www.dustspares.co.uk/ductwork-parts/.
Mini split systems
These systems use no ductwork parts but require a unit to be installed in each room, linked to an external compressor. They are relatively expensive but give greater independent control and mean no energy is wasted on rooms not in use. These make sense for hotels or as a quick independent solution for a newly built annexe.
Packaged heating and air
These combine heating and air cooling systems within a single small unit. They can be located inside or outside the building and are usually very energy efficient and easy to service; however, their heating power is restricted, so they are often limited to warmer climates or smaller homes.