2 and 3 Knobs
Electromechanical rotary-knob switch assemblies provide conventional control over basic air conditioning functions. Both 115V and 220V switches are available.
3-knob assemblies provide function selection (Off-Fan-Run), fan-speed control, and a room thermostat.
2-knob assemblies for tempered water systems provide function selection (Off-Fan-Run) and fan speed control. (In these systems the thermostat is on the air handler.)
1-knob assemblies provide function selection only (Off-Fan-Run).