Abstract: An apparatus and method are provided for maintaining a standby pressure in a fire suppression system. The fire suppression system includes at least on spray head and a drive source coupled to the at least one spray head by a supply line. The supply lines delivers extinguishing medium to the spray head. The drive source maintains a standby pressure of the extinguishing medium in the supply line when the system is inactive. A release line is coupled at a first end to the supply line. The release line includes a thermal expansion assembly. When the system is inactive and the standby pressure exceeds a first threshold, the thermal expansion assembly releases extinguishing medium from the system to reduce the standby pressure. When the system is active and the standby pressure exceeds the first threshold, the thermal expansion assembly does not release extinguishing medium from the system.