Johnson A421 Digital Temperature Controller
The A421 Series controls are single stage, electronic temperature controls with a single-pole, double-throw (SPDT) output relay. The controls feature an adjustable backlit LCD for viewing the temperature and status of other functions, and a three-button touchpad for setup and adjustment. An LED indicates the On/Off status of the output relay. The A421 control is 120 VAC.
The A421 controls provide heating or cooling control, sensor offset, temperature setback, adjustable anti-short cycle delay, and a restricted user adjustment mode. The temperature units can be displayed in °F or °C. The temperature adjustment range is -40 to 212°F or -40 to 100°C. The A421 automatically changes from heating and cooling. The A421 controls are available in Type 1/IP20 high-impact plastic enclosures suitable for surface or DIN rail mounting and Type 4X/IP66 watertight, corrosion-resistant surface mount enclosures.
- Use to heat or cool a fermentation environment
- For use with a refrigerator or freezer, it operates compressor when ambient temperature rises above your programmed temperature
- For use with a heater, it activates when the temperature drops too low
- Backlit display for even easier-to-read display
- Faster Programming with three-button interface
- Internal defrost settings
- Sensor probe monitors the inside temperature while the easy-to-read LCD display shows it in either Fahrenheit or Celsius
- Includes 6’ extension cord with plug and 6’ sensor leads
- No additional wiring for installation is needed
- 120 VAC line voltage
- Range: -40° F to 212° F
- NEMA 1 enclosure, suitable for dry environments