US Patent 7628123 Combined hot water supply system

A water heater constituting a combined hot water supply system opens, in starting operation in response to an instruction from a connection controller in STEP 1, a water-supply servo valve to an operation start opening As corresponding to a water quantity slightly larger than an ignition water quantity Fi in STEP 2. In STEP 5, the water heater maintains an opening of the water-supply servo valve at the operation start opening As until a detected temperature Th of a hot-water-supply temperature sensor reaches temperature near a target temperature Ta (Ta−β≦Th≦Ta+α) and limits a water supply quantity from a water supply pipe to be equal to or smaller than a flow rate corresponding to the operation start opening As.