Johnson Controls Electronic Digital Temperature Control, SPDT, 120V, 2m Cable

The A421 Series Electronic Temperature Controls are single-stage controls with a single-pole, double-throw (SPDT) output relay.

Line-Voltage Type 4X Electronic Temperature Control: Type 4X (NEMA), IP67 weathertight enclosure for surface-mount applications.
Rated for 120/240 VAC.
Includes an A99BB-200C temperature sensor with 6 ft 7-1/5 in. (2.0 m) cable.

A421 Controls feature a bright backlit LCD with adjustable brightness and a three-button touchpad interface that can be set up to restrict user adjustments. An LED indicates the output relay's On/Off status. Standard A421 Series control modules have simple On and Off temperature settings for heating or cooling, an adjustable anti-short cycle delay, temperature setback, and sensor offset capability. The temperature control range is -40 to 212°F or -40 to 100°C.

The A421 controls are available in (NEMA), IP67 (CE) watertight, corrosion resistant surface mount enclosures

Applications
The A421 Electronic Temperature Control can be used to control a wide variety of single-stage refrigeration or HVAC equipment. Sample temperature control applications include:
• temperature monitoring and alarming
• on/off control of boilers and chillers
• boiler and chiller pump control
• heating and cooling control
• floating temperature control of damper and valve actuators
• cooling tower fan control based on water temperature
• supply, makeup, and mixed air temperature control
• temperature actuated valve control
• supply and makeup air damper and fan control
• condenser fan control based on condenser temperature