A system for automatically controlling a drain valve connected to a sootblower steam piping system utilizes two temperature measurements, one near the steam source and the other near the drain valve. Comparison of the difference in steam temperature between these two locations with an adjustable temperature setpoint allows the drain valve to be opened to drain condensate and maintain minimum allowable superheat over a wide range of conditions. The system allows the temperature sensing to "float" with steam source conditions, since it is continuously adjusted to compensate for steam source temperature and ambient temperature changes.