The heaters transform the energy of the combustibles in heat and make it available to a circuit containing water or air. They can be of two types:
- Indirect: specifically thought for stations in which it's difficult to product hot water or steam for gas heating.
- Electrical: for applications in which a high power is not requested.

The heat exchangers are fundamental components for the air-conditioning of civil plants and for the thermoregulation of industrial plants in which an exchange of thermical energy between two fluids with a different temperature level is performed.