Equipment that transfers the heat of combustion to the Heating circuit  water. The Heat exchanger 
 is the main component in a Boiler 
/Heat generator 
 and has a critical effect on Efficiency 
.
- Heat exchanger
- Heat generator- Equipment that generates heat and transfers it to the Heating circuit - water. It reduces energy losses to a minimum by means of efficient heat exchangers and excellent heat insulation (Condensing boiler - ). 
- Heat of condensation- Additional heat from the flue gases. Condensation occurs when the flue gases cool, resulting in the release of additional energy. This additional potential – based on the Lower heating value - – is about 11 percent for natural gas, 9 percent for LPG, and 7 percent for fuel oil. 
- Heating boiler- Equipment which transfers the heat of combustion to the Heating circuit - water. The latest generation of Weishaupt boilers reduce energy losses to a minimum by means of efficient heat exchangers and excellent heat insulation. 
- Heating circuit- A system for supplying heat within buildings. It includes the pipework, radiators or underfloor heating, and electronic Circulation pumps - (Circulation pumps - ). 
- Heating curve- The Boiler - temperature is adjusted relative to the outdoor temperature by means of the heating (or temperature) curve. A low outdoor temperature results in a high Boiler - temperature. The setting-up of the Heating curve - is very important for efficient heating, and is carefully checked during maintenance. 
- Higher heating value- The amount of heat released through the complete combustion of a cubic metre of gas (at standard temperature and pressure) or a kilogram of fuel oil, when the water produced by the combustion is liquid. It is measured in kWh/m3 or kWh/kg. It is abbreviated to HHV or GCV (gross calorific value).