We provide life-long warranty service for the Water Heater Circuit Boards you buy in store. We provide the best quality service for the buyer. We pay special attention to the satisfaction of the buyer. As long as you need to contact us at any time, we will answer all your questions at the first time! COMPATIBLE MODEL: Compatible with DD-17-DSI NT-12S NT-12SE NT-16S NT-20S NT-16SE NT-20SE NT-24S NT-24SP NT-24M NT-25K NT-30SP; Compatible with NT-34S NT-42T SF-20 SF-20F SF-25 SF-25F SF-30 SF-30F SF-35 SF-35F SF-42 SF-42F; Compatible with Suburban SW4D, SW6D, SW6DE,SW6DEL,SW6DEM,SW6DM ,SW6, SW10. Replace for 521099 520871 520814 520820 33550L AP4896608. PRODUCT ADVANTAGES: Reliable performance: The board is designed with advanced circuitry and high-quality materials, ensuring stable and dependable performance. Precise temperature control: It offers precise temperature control functionality, allowing users to easily adjust the water heater's temperature. Efficient power management: The board features efficient power management capabilities, helping to save energy and improve overall efficiency. INSTALLATION STEPS: 1. Turn off the power: Before starting the installation, make sure to disconnect the power source 2. Access the circuit board location: Determine the location of the circuit board in the water heater. 3. Disconnect the old circuit board: If there is an existing circuit board, disconnect it. 4. Install the new circuit board: Insert the new 521099 circuit board into the corresponding slot or connector. 5. Connect the wires: Connect the wires to the appropriate plugs or connectors, ensure secure and correct connections. 6. Test and debug: After installation, reconnect the power and perform testing. Verify that the circuit board is functioning properly and check for any issues.