The Chromalox WCRT-100 thermostat is a heavy-duty, weather-corrosion-resistant room thermostat designed for temperature control in industrial and commercial heating applications. This device is engineered to manage electric air heaters and operate within a specified range of electrical and environmental conditions. The information provided in this guide is derived from the official installation manual and operational instructions for the Chromalox WCRT-100 thermostat. The document emphasizes proper installation procedures, mounting instructions, electrical connections, and safety considerations to ensure safe and effective operation.
Overview of Key Features and Specifications
The WCRT-100 thermostat is a single-pole, double-throw (SPDT) switch thermostat, allowing it to be wired either to open or close the circuit in response to temperature changes. It is rated for use with a wide range of electrical loads, including full-load inductive, locked-rotor, non-inductive, and pilot-duty applications. The thermostat operates within a temperature range of 40 to 100 degrees Fahrenheit and is not designed for temperature-limiting duty due to its failure-to-safe nature.
Below is a summary of the electrical ratings for the WCRT-100 thermostat:
| Electrical Rating | 120 Vac | 240 Vac | 277 Vac |
|---|---|---|---|
| Full Load Inductive | 16.0A | 12.0A | 10.0A |
| Locked Rotor | 80.0A | 60.0A | 55.0A |
| Non-Inductive | 25.0A | 25.0A | 22.0A |
| Pilot Duty | 125 VA | 125 VA | 125 VA |
These ratings are essential to consider when determining whether the thermostat can handle the electrical load of the connected heating equipment. It is also important to note that for higher-rated loads or three-phase applications, a contactor must be used in conjunction with the thermostat.
Installation Considerations
Proper installation is critical to the performance and safety of the WCRT-100 thermostat. The installation process involves several steps, including selecting an appropriate location, preparing the mounting surface, and connecting the electrical wiring in accordance with the device’s specifications and local electrical codes.
Location and Mounting
The thermostat should be mounted in a location that allows for free air circulation and is not subject to extreme temperature influences. It is recommended to install the thermostat away from outside walls, windows, doors, and other sources of heat or cold that may interfere with accurate temperature readings. Additionally, if the electrical conduit runs into a cooler or warmer room, it is advised to plug the space around the wires with rock wool to prevent temperature fluctuations from affecting the thermostat’s performance.
Mounting the thermostat is facilitated by four 1/4-inch diameter holes in the housing. A qualified technician should install the device using sheet metal or wood screws to secure it in place. The manual emphasizes the importance of following all local electrical codes and using a qualified professional for installation.
Wiring and Electrical Connections
The WCRT-100 thermostat is designed to be wired in accordance with standard electrical practices. The wiring entry is provided through a 1-inch conduit hole located at the top of the housing. The wiring should be installed in moisture-resistant conduit to ensure durability and safety.
The thermostat features an SPDT switch, allowing it to be configured to either open or close the circuit in response to temperature changes. For example, the black wire can be connected to the red wire to open the circuit when the temperature rises, or to the blue wire to close the circuit under the same conditions. This flexibility allows for customized control depending on the specific application and equipment requirements.
The manual provides detailed wiring diagrams in Figures 6 and 7 to guide the installer in making the correct connections. It is essential to make electrical connections with generous loops of wire—approximately 6 inches per lead—to ensure secure and reliable connections.
Safety and Compliance
The manual includes several warnings and notices to ensure safe installation and operation. One critical warning emphasizes the use of copper conductors only, as other types of wiring may not meet the required electrical and safety standards. Another warning states that the thermostat is not designed to fail safely, meaning it should not be used for temperature-limiting duty. Users are advised to install adequate backup controls and safety devices when using the thermostat with electric heating equipment.
Additionally, the manual highlights the importance of disconnecting all power before beginning any wiring or servicing tasks to avoid the risk of electrical shock. The non-metallic enclosure of the thermostat requires the use of a ground-type hub and a jumper wire for grounding purposes, ensuring compliance with electrical safety standards.
Operation and Application
The WCRT-100 thermostat is primarily used to control the on/off cycle of electric air heaters. It can be used directly to control the heaters within its rating capacity. For applications where the load exceeds the thermostat's electrical rating, a magnetic contactor must be used in conjunction with the thermostat. This setup ensures that the contactor handles the higher current demands while the thermostat provides the temperature-based control signal.
The thermostat should be installed on an interior wall, away from any undue heating or cooling influences, and at a height of approximately four feet from the floor. This placement helps ensure accurate temperature readings and consistent performance.
The manual also includes a notice that the WCRT-100 thermostat is designed for temperature control service only. It is not intended for use in safety-critical applications where the failure of the device could lead to severe consequences. In such cases, users are advised to implement additional backup controls and safety devices to mitigate risks.
Conclusion
The Chromalox WCRT-100 thermostat is a robust and reliable solution for temperature control in industrial and commercial heating applications. Its SPDT switch design allows for flexible configuration depending on the specific needs of the installation. However, it is important to note that the device is not designed for temperature-limiting duty and should be used in conjunction with additional safety controls when necessary.
Installation should be carried out by a qualified professional in accordance with the National Electrical Code and local regulations. The use of copper conductors, proper grounding, and secure electrical connections are essential to ensure safe and efficient operation. Users should also be aware of the thermostat's electrical ratings and use a contactor when handling higher-rated loads or three-phase applications.
By following the manufacturer's instructions and adhering to best practices, users can ensure that the WCRT-100 thermostat operates effectively and safely in a wide range of environments.