A hydronic system and method of use that will maintain normal system operating pressure while also reliably detecting even very small fluid losses in any closed loop fluid heat transfer system is described. The system includes a controller having clock or timing functionality in communication with one or more pressure sensors and a fluid supply valve that provides one or more notifications when the pressure drops below predetermined levels during predetermined periods of time. Depending on the nature of the pressure loss, the system has the capability of opening a fluid supply valve to provide make up fluid and increase system pressure.