The technical characteristics of bleeder water mixing tank are as follows: enable the relatively independent running of primary circulation and secondary circulation, the flow rate of each circulating system just depends on its water pump, so as to avoid the mutual interference caused by the series connection of pumps. If water mixing tank is used, the secondary circulating system will work only when its pump is started. When the pump of secondary circulating system is switched off, the flow capacity opened by the pump of primary circulating system will completely return to the primary system through the bypass inside the bleeder water mixing tank.