In these boilers, also called waste-heat recovery units, steam or hot water is produced by using exhaust gases or waste heat from other processes as the heat source. The boilers are often installed in the flue gas channels of incinerators.

Waste-heat boilers can offer capacity up to 120 t/h with a pressure of up to 120 bar(g).

To achieve better efficiency, an economiser can be installed. It makes optimum used of the waste heat and water in the steam boiler or hot water boiler. This leads to remarkable efficiency gains and significant (cost) savings.

Waste-heat boilers can also be equipped with superheaters, allowing for steam temperatures of up to 500 ^oC.