1. Installing Residential Central Air Conditioning Systems 24.11 This is a condensing unit with flared or brazed tubing connections and service valves. Refrigerant control is provided by a thermostatic expansion valve.

2. Rooftop Units 24.19 Rooftop units were originally developed for flat-roofed commercial structures.

3. 26.3 Thermostat Operation A bimetal-operated thermostat with four mercury switches (two are shown highlighted).

4. 1.18.5 Basic Refrigeration Cycle

5. 3.4 Low-Side Float Refrigerant Control Note the float needle, low- side float, and pressure motor control.

6. 3.5 External-Drive (Open) Refrigeration System

7. 3.12 Cascade Refrigerating Systems

10. 3.13 Modulating Refrigeration Cycle