A coolant-conditioning unit is provided which includes a facility coolant path, having a facility coolant flow control valve, and a system coolant path accommodating a system coolant, and having a bypass line with a system coolant bypass valve. A heat exchanger is coupled to the facility and system coolant paths to facilitate transfer of heat from the system coolant to facility coolant in the facility coolant path, and the bypass line is disposed in the system coolant path in parallel with the heat exchanger. A controller automatically controls a regulation position of the coolant bypass valve and a regulation position of the facility coolant flow control valve based on a temperature of the system coolant, and automatically adjusts the regulation position of the system coolant bypass valve to facilitate maintaining the facility coolant flow control valve at or above a specified, partially open, minimum regulation position.