The ultramodulating gas boiler as an opportunity for domestic energy saving

Domestic gas boilers on the market are able to modulate up to a modulation ratio equal to 10; in the present work the convenience of adopting modulation ratios up to 40 has been assessed. A methane condensing domestic boiler has been set up to work over the nominal modulation range up to 15, so that a consumption and efficiency experimental characterisation has been carried out and numerically extended to 40. A bin-method-based model has been implemented in order to estimate the modified boiler consumption for different scenarios. An increasing in the modulation ratio improves the overall boiler efficiency by reducing cycling losses yet rises the operating time and the electrical consumption; accordingly, in the present work a comprehensive analysis has been performed to identify optimal ‘ultra-modulating’ ratios for different climates and buildings.