The invention relates to a dual-purpose furnace working
system which comprises a
combustion heat-exchanging device, a
fuel gas pipeline, a heating pipeline, a domestic water pipeline, a heat exchangerand an expansion water tank. The expansion water tank is provided with a first cavity, a second cavity and a third cavity. The first cavity communicates with the heating pipeline, the second cavity communicates with the domestic water pipeline, and the third cavity communicates with a balance air source. The dual-purpose furnace
system can provide hot water sources for domestic water and heatingwater simultaneously, in the heating process, the domestic water is supplied as a priority, and energy is effectively utilized; two cavities of the expansion water tank are simultaneously connected toa heating waterway and a domestic waterway of a dual-purpose furnace in series, the expansion and shrinking quantity of circulating water in a heating loop and the expansion and shrinking quantity ofwater in the domestic waterway can be contained and supplemented, and pressure fluctuation of the heating loop and the domestic water can further be relieved; and stability of the
water flow rate iskept, and the use comfort of the bathroom domestic water is improved while the heating function is ensured.