1. Introduction
This manual provides essential instructions for the safe and efficient installation, operation, and maintenance of your RANCO Electronic Temperature Control unit. This device is designed to provide precise temperature regulation for heating, cooling, and refrigeration applications, featuring a liquid crystal display (LCD) for constant temperature readout and diagnostic error codes.
2. Safety Information
WARNING: Risk of Electric Shock. Disconnect power before installation or servicing.
- Installation and servicing must be performed by qualified personnel only.
- Ensure all wiring complies with local and national electrical codes.
- Verify the power supply voltage matches the unit's specifications (120/208/240VAC).
- Do not operate the unit if it appears damaged.
- The enclosure type is NEMA 1, suitable for indoor use, providing protection against falling dirt.
3. Product Overview
The RANCO Electronic Temperature Control is a versatile line voltage thermostat equipped with an LCD for clear temperature display and operational feedback. It includes features such as keypad lockout, memory for settings, and a time delay on power-up to protect connected equipment.
Figure 1: RANCO Electronic Temperature Control unit. This image displays the gray rectangular control unit featuring an LCD screen and three control buttons (SET, Up, Down) on its front panel. A gray cable exits from the top, and another gray cable with a black cylindrical temperature sensor extends from the bottom. The unit's casing is secured by screws at its corners.
4. Setup and Installation
4.1 Mounting
Mount the control unit in a location that is easily accessible for viewing and operation, and where it is protected from moisture and excessive vibration. Ensure the NEMA 1 enclosure rating is appropriate for the environment.
4.2 Wiring
Connect the control unit to the appropriate power supply (120/208/240VAC) and to the controlled equipment (heating, cooling, or refrigeration system) according to the wiring diagram provided with the unit. The unit features one SPDT (Single Pole Double Throw) relay for output control. Ensure all connections are secure and insulated.
4.3 Sensor Placement
The thermistor sensor (1/4" diameter, 2" length) should be placed in the area where temperature is to be monitored. Ensure the sensor is not exposed to direct drafts or heat sources that could provide inaccurate readings. The sensor cable should be routed to avoid damage or interference.
5. Operating Instructions
5.1 Power Up
Upon initial power-up, the unit will undergo a time delay before operation begins. The LCD will display the sensed temperature.
5.2 Setting Temperature
- Press the SET button to enter the setpoint adjustment mode.
- Use the Up and Down arrow buttons to adjust the desired temperature setpoint.
- Press SET again to confirm and save the new setpoint, or wait a few seconds for the unit to automatically save and exit.
5.3 Adjusting Differential
The differential (hysteresis) can be set between 1 and 30 degrees Fahrenheit. Refer to the full product manual for specific steps to access and adjust this parameter, as it typically involves a combination of button presses.
5.4 Keypad Lockout
The unit features a keypad lockout function to prevent unauthorized changes to settings. Consult the detailed product manual for instructions on how to activate and deactivate this feature.
5.5 Error Codes
The LCD display will show specific error codes if a problem is detected, particularly related to refrigeration. Refer to the comprehensive product manual for a list of error codes and their corresponding troubleshooting steps.
6. Maintenance
- Keep the unit clean and free from dust and debris. Use a soft, dry cloth for cleaning.
- Periodically inspect wiring connections for tightness and signs of wear.
- Ensure the temperature sensor is clean and properly positioned.
- No user-serviceable parts are inside the unit. Refer all repairs to qualified service personnel.
7. Troubleshooting
- No Display: Check power supply connections. Ensure the unit is receiving the correct voltage.
- Incorrect Temperature Reading: Verify sensor placement and ensure it is not damaged. Check for proper sensor connection.
- Unit Not Controlling: Check setpoint and differential settings. Verify wiring to the controlled equipment. Look for any error codes on the display.
- Error Codes Displayed: Consult the full product manual for specific error code definitions and recommended actions.
If problems persist after performing these checks, contact qualified service personnel.
8. Specifications
| Feature | Specification |
|---|---|
| Item | Electronic Temperature Control |
| Switch Type | SPDT |
| Switch Action | Open/Close on Rise |
| Voltage Range | 120/208/240VAC |
| Control Range | -30°F to 220°F |
| Differential | 1°F to 30°F |
| Number of Relay Inputs | 1 |
| Number of Relay Outputs | 1 |
| Full Load Amps @ 120VAC | 16A (NO), 5.8A (NC) |
| Full Load Amps @ 240VAC | 8A (NO), 2.9A (NC) |
| Sensor Type | Thermistor |
| Sensing Bulb Diameter | 1/4" |
| Sensing Bulb Length | 2" |
| Enclosure Type | NEMA 1 |
| Height | 6-1/2" |
| Width | 2-3/4" |
| Depth | 2-1/2" |
| Color | Gray |
| Display Type | LCD |
| Certifications | UL Listed, CSA Certified |
| Applications | Heating, Cooling, Refrigeration |
9. Warranty and Support
For warranty information and technical support, please refer to the documentation provided with your purchase or contact Ranco customer service directly. Keep your purchase receipt as proof of purchase.