Which of the following is true concerning...

🔍 Key Concepts

• Trace the chilled water and steam lines to see what actually produces cooling and heating in this system. • Note how the room thermostat (T), sub-master (SM), and master (M) are connected pneumatically to valves, dampers, and the dual duct air mixing unit (M). • Review how recirculated air vs. outside air affects the heat load on an air conditioning system.

💭 Think About

• Look at the cooling section: does this diagram show a self-contained Freon (refrigerant) unit, or does it show a chilled-water coil supplied from somewhere else? What does that imply about choice A? • Follow the control lines from the room thermostat: do they go directly to a steam valve, to the preheater, or to the mixing box that blends hot and cold air? • Think about heat load: if you bring in more already-conditioned recirculated air instead of hot (or cold) outside air, does the refrigeration system work harder or less?

✅ Before You Answer

• Verify which component actually cools the air: is it a Freon evaporator or a chilled water coil (C)? • Confirm which thermostat or controller is tied to the preheater steam valve versus the reheater steam valve and the dual duct mixing unit. • Check whether increasing recirculated air would increase or decrease the temperature difference the system must overcome, and therefore the cooling/heating load.

Which of the following is true concerning the class "G" air conditioning system shown in the following illustration? See illustration GS-RA-43.

System cooling is the direct result of the Freon circuit of a direct type air conditioning unit.

The room thermostat controls the degree of mixing of the cold and hot air at the dual duct air mixing unit.

The sub master thermostat controls the steam flow through the preheat coil and its associated pneumatic control valve.

The heat load will increase by increasing the amount of recirculated air.

🔍 Key Concepts

💭 Think About

✅ Before You Answer