This document is an installation manual for the Robertshaw RS10421T WiFi digital programmable thermostat. It provides instructions for installation, setup, programming, and troubleshooting, along with technical specifications and safety warnings.
Function Description:
The Robertshaw RS10421T is a WiFi digital programmable thermostat designed to control the temperature in residential and light commercial HVAC systems. It allows users to control the temperature remotely via an iOS or Android smartphone application. The thermostat features a large backlit LCD touchscreen for ease of programming and operation. It is compatible with a variety of HVAC system types, including:
- Gas, Oil, or Electric Furnaces
- Heat Pumps (with or without auxiliary or emergency heat)
- Multi-Stage Systems
- Heat Only systems (including floor and wall furnaces)
- Cool Only systems
- Millivolt Heating Systems
Important Technical Specifications:
- Display Range: 32°F to 99°F (0°C to 40°C)
- Control Range: 41°F to 90°F (5°C to 32°C)
- Load Rating: 1 amp per terminal, 1.5 amp maximum for all terminals combined
- Differential:
- Heating: Adjustable from 0.2° to 2.0°
- Cooling: Adjustable from 0.2° to 2.0°
- Power Source: 18 to 30 VAC, NEC Class II, 50/60 Hz for hardwire
- Operating Ambient Temperature: 32°F to +105°F (0°C to +41°C)
- Operating Humidity: 90% Non-Condensing Maximum
- Dimensions: 4.7" W x 4.4" H x 1" D
- Operating Frequency: 433.92 MHz (for optional accessory)
- Voltage: 18-30V AC low voltage thermostat. Not for use on voltages higher than 30V AC.
- Wiring: Uses 18- to 22-gauge thermostat wire; shielded wire is not required.
Usage Features:
- WiFi Connectivity: Allows remote temperature control via a dedicated smartphone app (iOS and Android).
- LCD Touchscreen: Provides an intuitive interface for programming and adjustments.
- Programmable Time Periods: Residential settings use four time periods: WAKE, LEAVE, RETURN, and SLEEP.
- System Operation Indicators: Icons flash to indicate a 5-minute delay for compressor protection.
- Setpoint Control: Displays user-selected setpoint temperature.
- Fan Control: Includes "Auto" and "On" fan settings, with an "IAQ" option for indoor air quality fan cycles.
- System Modes: Supports Heat, Cool, Auto, and Emergency Heat modes.
- Temperature Display: Can be set to Fahrenheit (°F) or Celsius (°C).
- Clock Settings: Supports 12-hour or 24-hour clock display.
- Morning Recovery: Starts heating early to reach the programmed setpoint by the WAKE period.
- Display Light: Configurable to turn on with any key press or stay on continuously.
- Contractor Call Number: Allows input of a phone number to be displayed.
- Humidity Control:
- Humidify: Adds humidity in HEAT mode, energizing the HUM terminal when humidity setpoint is above ambient.
- Dehumidify: Removes humidity in COOL mode, energizing the DHM terminal when humidity setpoint is below ambient.
- Optional Outdoor Sensor (RS9055OUT):
- Wireless outdoor remote temperature sensor.
- Durable weatherproof design.
- Compatible with RS9423T or RS10421T thermostats.
- Wireless range up to 328 feet (100m).
- Battery powered (two AA Alkaline batteries).
- Used for dual fuel balance point applications, switching between electric and oil heating based on induction temperature and dual fuel setting.
Maintenance Features:
- Filter Change Reminder: Adjustable from OFF to 2000 hours in 50-hour increments, reminding the user to change the filter.
- Room Temperature Calibration: Allows adjustment of the displayed room temperature by up to 4° above or below the factory calibrated temperature.
- Minimum Compressor On-Time: Selectable from OFF, 3, 4, or 5 minutes to protect the compressor from short-cycling.
- Compressor Short Cycle Delay: Prevents the compressor from turning on for 5 minutes after it was last turned off, protecting the compressor. Can be removed by selecting OFF.
- Heating and Cooling Swing: Adjustable differential (0.2°F to 2.0°F) to control how often the heating/cooling system turns on.
- Humidity Calibration: Allows adjustment of the ambient humidity display by +/-3 units (approximately 5% per unit).
- Factory Default Reset: Resets all WiFi settings to factory default.
- Firmware Version Display: Shows the installed firmware version.
- Keypad Lockout: Activates a lockout feature after exiting technician setup by holding the MENU button for 3 seconds.
- Always turn off power at the main source (fuse or circuit breaker) before installation, removal, cleaning, or servicing.
- Do not short (jumper) across terminals on the gas valve or system control to test installation, as this will damage the thermostat and void the warranty.
- This product is mercury-free. If replacing a mercury-containing control, dispose of it properly according to local waste management authorities.
- Disconnect power before installing to prevent electric shock or equipment damage.
- Do not over-tighten terminal screws (maximum torque 6 in-lbs) to avoid damaging the terminal block and preventing proper operation.
- Place nonflammable insulation into the wall opening to prevent drafts.
- Devices like float switches should break the control wire (Y), not the power (R), to ensure the thermostat continues to operate.
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