King Thermostat Manual: A Comprehensive Guide
Welcome! This manual provides detailed instructions for installing, operating, and maintaining your King thermostat, ensuring optimal comfort and energy efficiency within your home.

King Thermostats are renowned for their reliability and precision in maintaining comfortable indoor temperatures. Designed with both residential and light commercial applications in mind, these thermostats offer a blend of user-friendly operation and advanced features;
For decades, King has been a trusted name in the HVAC industry, consistently delivering products built to last. Their thermostats cater to a wide range of heating and cooling systems, including forced air, heat pumps, and electric baseboard heaters.
This manual serves as a comprehensive resource, guiding you through every aspect of your King thermostat – from initial setup and programming to troubleshooting and routine maintenance. Whether you’re a homeowner or a professional installer, you’ll find valuable information within these pages to maximize your thermostat’s performance and extend its lifespan. Understanding your thermostat is key to enjoying consistent comfort and reduced energy costs.
Understanding Your King Thermostat Model
King thermostats come in various models, each tailored to specific heating and cooling system configurations. Before proceeding, it’s crucial to identify your exact model number to ensure you’re referencing the correct information. This number is typically located on the back of the thermostat unit, or on the original packaging.
Different models offer varying features, such as programmable schedules, Wi-Fi connectivity, and compatibility with smart home systems. Some are designed for simple, manual operation, while others boast advanced energy-saving capabilities.
This section will help you differentiate between the core functionalities available across the King thermostat range. Knowing the capabilities of your specific model will unlock its full potential and allow you to customize your comfort settings effectively. Refer to the following sections to pinpoint your model and its unique features.
2.1 Identifying Your Specific Model Number
Locating your King thermostat’s model number is the first step towards accessing the correct support and documentation. The model number is a unique identifier that specifies the features and capabilities of your particular unit. Typically, you’ll find it printed on a sticker located on the back of the thermostat itself.

Carefully remove the thermostat from its wall plate to access this sticker. Alternatively, check the original packaging the thermostat came in – the model number should be printed on the box or accompanying documentation.
Commonly, the model number will begin with “KT” followed by a series of numbers and letters. Record this number as you’ll need it when referencing wiring diagrams, troubleshooting guides, and accessing online resources. Knowing your model number ensures you receive accurate and relevant information.
2.2 Key Features & Benefits
King thermostats are designed with user convenience and energy savings in mind. Many models boast large, easy-to-read displays, simplifying temperature adjustments and mode selections. Programmable options allow for customized heating and cooling schedules, reducing energy consumption when you’re away or asleep.
Several King thermostats offer compatibility with various heating systems, including electric baseboard, fan-forced, and radiant heat. Advanced features, such as smart learning and Wi-Fi connectivity (on select models), provide remote control and intelligent temperature management via smartphone apps.
Benefits include consistent comfort, reduced energy bills, and enhanced control over your home’s climate. The intuitive interface and reliable performance make King thermostats a smart choice for any homeowner seeking a comfortable and efficient heating solution.
Installation Guide
Proper installation is crucial for optimal performance of your King thermostat. This section provides a step-by-step guide, but always prioritize safety. Before beginning, turn off power to your heating system at the breaker box to avoid electrical shock. Carefully remove your old thermostat, noting the wiring configuration.
Use the provided wiring diagram (see section 3.2) to connect the wires to the corresponding terminals on the new King thermostat baseplate. Ensure connections are secure and properly insulated. Once wired, mount the baseplate to the wall using the included screws, ensuring it’s level.
Finally, attach the thermostat body to the baseplate. Restore power at the breaker box and verify the thermostat powers on correctly. Refer to the troubleshooting section if you encounter any issues during installation.
3.1 Safety Precautions Before Installation
Electrical Safety First! Disconnect power to your HVAC system at the breaker box before starting any installation work. Failure to do so could result in serious injury or death. If you are uncomfortable working with electrical wiring, consult a qualified HVAC technician.
Verify that your existing wiring is compatible with the King thermostat. Incorrect wiring can damage the thermostat or your HVAC system; Always use insulated tools and wear appropriate safety glasses. Keep children and pets away from the work area.
Double-check all connections before restoring power. Ensure no bare wires are exposed. If you smell burning plastic or see smoke, immediately turn off the power and investigate the issue. Ignoring these precautions can be dangerous.
3.2 Wiring Diagrams (Common Models)

Important: These diagrams are for common King thermostat models. Always refer to the wiring diagram specific to your model number (see Section 2.1). Incorrect wiring can cause system malfunction or damage.

Typical Wiring: R (24V Power), C (Common), W (Heat), Y (Cool), G (Fan). Some models may include O/B (Reversing Valve) for heat pumps. Diagrams will illustrate these connections clearly.
Heat Pump Wiring: Heat pump systems often require more complex wiring configurations. Pay close attention to the O/B terminal designation – it varies by manufacturer.
Digital images of wiring diagrams for models KT300, KT400, and KT500 are provided below. If your model isn’t listed, consult the documentation included with your thermostat or contact King customer support.
3.3 Mounting the Thermostat
Preparation is key! Before mounting, ensure the wiring is correctly connected (Section 3.2) and safely tucked away within the wall. Use the provided mounting plate as a template, marking the screw locations on the wall.
Drilling & Anchors: Drill pilot holes at the marked locations. If mounting to drywall, use the supplied wall anchors for a secure fit. Avoid drilling into electrical wiring or plumbing!
Securing the Plate: Attach the mounting plate to the wall using the provided screws. Ensure it is level for accurate temperature readings and a professional appearance.

Attaching the Thermostat: Carefully align the thermostat body with the mounting plate and gently snap it into place. A firm click indicates a secure connection. Do not force it!
Basic Operation: Setting Temperature
Initial Setup: After powering on, your King thermostat displays the current room temperature. To adjust the desired temperature, utilize the intuitive controls – typically up and down arrow buttons.
Temperature Adjustment: Press the “Up” button to increase the setpoint temperature, and the “Down” button to decrease it. Each press usually adjusts the temperature by one degree Fahrenheit (or Celsius, depending on your settings).
Display Confirmation: The desired setpoint temperature will be prominently displayed on the thermostat’s screen. Allow a few moments for the system to respond to the new setting.
System Response: Once the room temperature deviates from the setpoint, the heating or cooling system will activate accordingly, striving to maintain your desired comfort level. Observe the system indicator!
4.1 Using the Up and Down Buttons
Core Functionality: The up and down buttons are your primary interface for controlling the King thermostat. These buttons facilitate temperature adjustments, menu navigation, and setting value changes.
Temperature Control: In the main display, pressing the “Up” button increases the set temperature, while the “Down” button decreases it. The display clearly shows the new setpoint.
Menu Navigation: Within the thermostat’s menu, these buttons scroll through available options. Use them to select settings like fan control, scheduling, or system mode.
Value Adjustment: When modifying a setting (e.g., setting a schedule time), the up and down buttons increment or decrement the value. Confirm your selection with the ‘Select’ or ‘Enter’ button.
Button Feedback: A visual or audible cue (like a beep or screen change) confirms each button press, ensuring accurate input.
4.2 Understanding Heat, Cool, and Auto Modes
Operational Modes Explained: Your King thermostat offers three primary operating modes: Heat, Cool, and Auto. Each mode dictates how the thermostat manages your home’s temperature.
Heat Mode: In Heat mode, the thermostat activates your heating system when the room temperature falls below the setpoint. It maintains the desired warmth by cycling the heater on and off.
Cool Mode: Conversely, Cool mode activates your cooling system when the room temperature exceeds the setpoint, providing air conditioning to maintain a comfortable coolness.
Auto Mode: Auto mode intelligently switches between heating and cooling to maintain the set temperature. The thermostat determines whether to activate heating or cooling based on the difference between the setpoint and the current room temperature.
Mode Selection: You can typically switch between these modes using the thermostat’s menu or dedicated mode buttons; Selecting the appropriate mode ensures optimal comfort and energy efficiency.
Programming Your Thermostat
Maximize Comfort & Savings: Programming your King thermostat allows you to create a customized heating and cooling schedule, optimizing both comfort and energy savings. Instead of manually adjusting the temperature throughout the day, you can pre-set preferences for different times and days.
Schedule Creation: The programming function typically involves setting different temperature setpoints for various periods, such as waking hours, daytime, evening, and sleep. This ensures the temperature is ideal when you’re home and awake, and lower when you’re away or asleep.
User-Friendly Interface: Most King thermostats feature a straightforward menu system for programming. You’ll navigate through options to set start times, temperatures, and days of the week for each period.
Energy Efficiency: A well-programmed thermostat can significantly reduce energy consumption, leading to lower utility bills and a smaller carbon footprint. Take the time to tailor the schedule to your lifestyle!

5.1 Setting a Daily Schedule
Creating Your Ideal Daily Comfort: To set a daily schedule, begin by accessing the “Schedule” or “Program” menu on your King thermostat. You’ll typically define four periods: Wake, Leave, Return, and Sleep. Each period requires a start time and a desired temperature setting.
Wake Period: Set the “Wake” period to begin shortly before you typically wake up, and program a comfortable temperature for starting your day.
Leave & Return Periods: Program the “Leave” period to activate when you leave for work or other activities, setting a lower (for heating) or higher (for cooling) temperature to save energy. The “Return” period should correspond to your arrival time, restoring a comfortable temperature.
Sleep Period: Finally, set the “Sleep” period to begin before bedtime, lowering the temperature for optimal sleeping conditions and continued energy savings. Review and adjust as needed!
5.2 Utilizing 7-Day Programming
Tailoring Comfort to Your Week: Many King thermostats offer 7-day programming, allowing you to create unique schedules for each day of the week. This is ideal if your routine varies significantly between weekdays and weekends. Access the “7-Day Schedule” option within the programming menu.
Individual Day Customization: You’ll be presented with each day of the week (Monday-Sunday). Select a day and program the Wake, Leave, Return, and Sleep periods as described in the daily schedule section. Repeat this process for each day.
Copying Schedules: To save time, some models allow you to copy a schedule from one day to another. This is useful if several days share a similar routine. Remember to review each day’s schedule to ensure it accurately reflects your needs. Enjoy personalized comfort!
5.3 Temporary Holds & Overrides
Adjusting for the Unexpected: Sometimes, your schedule changes unexpectedly. King thermostats offer “Temporary Hold” and “Override” features to accommodate these situations without permanently altering your programmed schedule. A Temporary Hold maintains a set temperature for a specified duration, after which the thermostat reverts to its programmed schedule.
Initiating a Hold: To activate a Temporary Hold, manually adjust the temperature using the up/down buttons. Select the “Hold” option and specify the hold duration (e.g., 2 hours, 4 hours, until next scheduled change). An Override functions similarly, but typically lasts until the next programmed period begins.
Cancelling a Hold/Override: To cancel a hold or override, simply return to the programmed schedule mode. Your thermostat will resume its regularly scheduled operation. These features provide flexibility and ensure comfort when life deviates from the norm.
Advanced Features & Settings
Beyond Basic Control: King thermostats offer several advanced features to optimize performance and personalize your comfort. Fan Control allows you to select “Auto” mode, where the fan operates only during heating or cooling cycles, or “On” mode for continuous air circulation.
Maintenance Reminders: The Filter Change Reminder feature helps maintain air quality by alerting you when it’s time to replace your air filter, promoting efficient system operation. Backlight Adjustment lets you customize the display brightness for optimal visibility in various lighting conditions.
Some models include advanced settings like swing adjustment, temperature calibration, and cycle rate control. Consult your specific model’s documentation for detailed instructions on accessing and configuring these features. These settings empower you to fine-tune your thermostat for peak performance.

6.1 Fan Control Options (Auto, On)
Managing Air Circulation: Your King thermostat provides two primary fan control settings: “Auto” and “On”. Selecting “Auto” mode ensures the fan operates solely during heating or cooling cycles. This conserves energy and maintains consistent temperature distribution. When the system isn’t actively heating or cooling, the fan remains off.
Conversely, choosing “On” mode forces the fan to run continuously, regardless of whether heating or cooling is engaged. This provides constant air circulation, which can improve air quality and even out temperature variations throughout your home.
To switch between these modes, navigate to the “Fan” setting in your thermostat’s menu. Consider your preferences and home environment when selecting the optimal fan control option for consistent comfort.
6.2 Filter Change Reminders
Maintaining Air Quality: Your King thermostat features a helpful filter change reminder system, crucial for optimal HVAC performance and indoor air quality. A dirty filter restricts airflow, reducing efficiency and potentially damaging your system. The thermostat allows you to set a reminder based on time (e.g., every 30, 60, or 90 days) or runtime hours.
To configure the reminder, access the “Filter” or “Maintenance” section within the thermostat’s menu. Once set, the thermostat will display a notification when a filter change is due. Regularly replacing your air filter – typically every 1-3 months – ensures efficient operation and cleaner air. Refer to your filter’s packaging for specific replacement guidelines.
6.3 Backlight Adjustment
Enhanced Visibility: Your King thermostat incorporates a convenient backlight feature for easy viewing in low-light conditions. The brightness level is adjustable to suit your preference and minimize nighttime glare. Access the backlight settings through the thermostat’s “Display” or “Settings” menu. Options typically include “Off,” “Low,” “Medium,” and “High” brightness levels.
You may also find an “Auto” setting, which automatically dims the backlight after a period of inactivity, conserving energy. Experiment with different brightness levels to find what works best for your environment. A dimmer setting is ideal for bedrooms, while a brighter setting may be preferable in frequently used areas. Adjusting the backlight ensures clear readability without causing distraction.
Troubleshooting Common Issues
Addressing Problems: This section outlines solutions to frequently encountered issues with your King thermostat. If your thermostat isn’t responding, first check the power supply and ensure the batteries (if applicable) are fresh. For inaccurate temperature readings, verify the thermostat isn’t exposed to direct sunlight or drafts. Recalibration may also be necessary via the settings menu.
Connectivity problems with Wi-Fi models often stem from router issues; ensure a stable internet connection and correct password entry. If the system isn’t switching between heating and cooling, double-check your programmed schedule and mode settings. If problems persist, a reset to factory defaults (consult your model’s specific instructions) can often resolve software glitches. If none of these steps work, contact King’s customer support.
7.1 Thermostat Not Turning On
Power Check: If your King thermostat fails to power on, begin by verifying the power source. For battery-powered models, replace the batteries with fresh ones, ensuring correct polarity. If hardwired, check the circuit breaker in your electrical panel to confirm it hasn’t tripped. Inspect the wiring connections at the thermostat and the HVAC system; loose connections can interrupt power flow.
Ensure the thermostat is securely mounted and the wiring hasn’t become dislodged during installation or maintenance. A blown fuse within the HVAC system could also be the culprit. If the display remains blank after these checks, consult a qualified HVAC technician to diagnose potential issues with the transformer or internal thermostat components. Do not attempt repairs yourself if you are uncomfortable working with electrical systems.
7.2 Inaccurate Temperature Readings
Calibration & Placement: If your King thermostat displays temperatures significantly different from the actual room temperature, several factors could be at play. First, ensure the thermostat isn’t directly exposed to sunlight, drafts, or heat-generating appliances. These can skew readings. Check for obstructions blocking airflow around the thermostat.
Many King thermostats offer a temperature calibration feature; consult your specific model’s programming section to adjust the displayed temperature. If calibration doesn’t resolve the issue, verify the thermostat is level. An unlevel installation can affect accuracy. Consider using a separate, calibrated thermometer to compare readings and confirm the extent of the discrepancy. If problems persist, professional HVAC assistance may be needed to assess sensor functionality.
7.3 Connectivity Problems (Wi-Fi Models)
Troubleshooting Wi-Fi: If your King Wi-Fi thermostat is experiencing connectivity issues, begin by verifying your home’s internet connection is active and functioning correctly. Ensure the thermostat is within range of your Wi-Fi router. Restart both your router and the thermostat – a simple reboot often resolves temporary glitches.

Double-check that you entered the correct Wi-Fi password during setup. If the signal strength is weak, consider relocating the router or using a Wi-Fi extender. Confirm your router’s firewall isn’t blocking the thermostat’s access. Refer to the King thermostat app for specific troubleshooting steps and error codes. If issues continue, consult King’s support website or contact customer service for assistance.
Maintenance & Care
Keeping Your Thermostat Optimal: Regular maintenance ensures your King thermostat operates efficiently and accurately for years to come. Gently clean the thermostat’s exterior with a soft, dry cloth. Avoid using liquids or abrasive cleaners, as these can damage the display or internal components.
Periodically check the thermostat’s mounting to ensure it remains secure. If you’ve enabled filter change reminders (see section 6.2), adhere to the recommended schedule for replacing your HVAC system’s air filter. A clean filter improves airflow and system performance. Avoid exposing the thermostat to extreme temperatures or humidity. For Wi-Fi models, ensure the firmware is updated through the app for optimal performance and security.