Question 472General Subjects - Assistant Engineer

70% to pass

In the illustrated terminal reheat multiple zone system, what statement represents the functioning of the supply air duct thermostats controlling the preheater steam flow and the cooling coil chilled water flow? Illustration GS-RA-42

AThe thermostat controlling the preheater steam flow is set several degrees lower than the design cooling coil off-coil temperature to prevent simultaneous flows.

BThe thermostat controlling the preheater steam flow is set several degrees higher than the design cooling coil off-coil temperature to prevent simultaneous flows.

CThe thermostat controlling the preheater steam flow is set at the design cooling coil off-coil temperature to allow simultaneous flows.

DThe thermostat controlling the preheater steam flow is set at the design cooling coil off-coil temperature to prevent simultaneous flows.

AI Explanation

The correct answer is A) The thermostat controlling the preheater steam flow is set several degrees lower than the design cooling coil off-coil temperature to prevent simultaneous flows. This is correct because the system is designed to avoid simultaneous heating and cooling, which would be inefficient. By setting the preheater thermostat a few degrees lower than the cooling coil off-coil temperature, the system ensures that the preheater will turn off before the cooling coil turns on, preventing the waste of energy from heating and cooling at the same time. The other options are incorrect because B) and C) would allow simultaneous heating and cooling, while D) would not prevent it.