Question 467General Subjects - Assistant Engineer

The correct answer is A) The supply air duct thermostat controlling the steam flow is set several degrees lower than the design off-coil temperature associated with the cooling coil. This is correct because the supply air duct thermostat controlling the steam flow is designed to only allow steam flow when the air temperature is below a certain threshold, which is set lower than the design off-coil temperature of the cooling coil. This prevents the simultaneous flow of steam through the preheat coil and chilled water through the cooling coil, which would result in energy waste and inefficient system operation. The other options are incorrect because they either do not prevent the simultaneous flow (option D) or set the thermostat at the wrong temperature relative to the cooling coil design (options B and C).