Application of Gas Condensing Boilers in Domestic Heating

Abstract

A growing number of households have had condensing boilers built in to be used for the heating of spaces and for the hot water supply. The use of condensing boilers is justified from the point of view of energy because they achieve higher thermal efficiency than traditional boilers. Condensation of water vapour occurs in the flue gases, whereby the heat released by condensation is used to heat the water in the boiler. How much water vapour will condense depends on the temperature to which the flue gases are cooled. In this paper, a thermodynamic analysis of thirteen built-in gas condensing boilers was performed; data on the flue gas composition and temperature, as well as on the excess air required for combustion were obtained for that purpose. The calculation results consisting of the amount of condensed water, the thermal efficiency of the boiler, and the volume flow rates of the air and fuel are presented in tables. The analysis identified the cases in which the water vapour condensation occurred and determined the amount of the condensed water. The cases without water vapour condensation were also identified.