Gas calorific value boiler

摘要

The backflow (22) of the used water heat exchanger (19) is switched to the high temperature heat exchanger (8) and the backflow (17) of the heating circuit (16) is switched to the low temperature heat exchanger (12). A three-way valve (23) is connected into the backflow (22) to the high temperature heat exchanger from which an interconnection (24) leads to the low temperature heat exchanger backflow (14). The three-way valve then produces a connection to the low temperature backflow when the temperature or output of the water flowing back from the used water heat exchanger would anticipate condensation in the low temperature heat exchanger.