It may be because of the size of the unit and the steam pressure supplied. Our unit opens all valves upon reset, this is to verify or ensure proper pressure and flow through the entire unit. With the valves shut or almost shut some sections of the turbine are actually under a vacuum or may have no flow. With no flow windage can occur and heat can increase rapidly, so on your unit it may be just to ensure the unit heats up uniformly. Sometime with hi pressure inlets and low flow the pressure drop can be great. This is just my take on it hope it helps, great question. Doug