Have you ever stepped into the shower only to be greeted by a sudden blast of cold water? If you own an A.O. Smith tankless water heater, you might have encountered error code 111, which can be a frustrating experience. This code often indicates a problem with the unit’s ignition or gas supply, leaving you wondering what to do next.
Don’t worry; you’re not alone. Many homeowners face this issue, but understanding it can save you time and money. In this article, you’ll learn what error code 111 means, common causes behind it, and practical steps to troubleshoot the problem. By the end, you’ll feel more confident in handling this hiccup and getting your hot water back on track.
Key Takeaways
- Understanding Error Code 111: This code indicates ignition or gas supply issues in A.O. Smith tankless water heaters, leading to a lack of hot water.
- Common Causes: Error code 111 can arise from insufficient gas pressure, blockages in the gas line, or malfunctioning ignition components.
- Troubleshooting Steps: Check the gas supply, inspect ignition components, ensure power to the unit, reset the system, and consult the user manual for guidance.
- Preventive Maintenance: Regularly check the gas supply, perform descaling, clean filters, inspect venting systems, and test safety features to avoid future issues.
- Professional Help: If troubleshooting does not resolve the problem, consulting a qualified technician is advisable for further assistance.
Overview of AO Smith Tankless Water Heaters
AO Smith tankless water heaters provide a continuous supply of hot water, maximizing energy efficiency for homeowners. Unlike traditional water heaters, these units heat water on demand. This feature eliminates the need for a bulky tank, freeing up space in your home.
Key Features
- Energy Efficiency: AO Smith models can save you up to 40% on energy costs compared to conventional heaters. They only heat water when you need it, reducing energy waste.
- Compact Design: These heaters are compact and can be installed in various locations, from utility rooms to under sinks.
- Long Lifespan: AO Smith units typically last longer than tank models, often exceeding 20 years with proper maintenance.
- Smart Technology: Many models offer Wi-Fi capabilities for remote monitoring and control through your smartphone.
Common Models
- AOS-700: Ideal for smaller households, it provides sufficient hot water for multiple outlets simultaneously.
- AOS-1000: Suited for larger homes, it supports heavy usage from multiple bathrooms and appliances.
- AOS-1500: Designed for commercial applications, this unit meets high-demand hot water needs effectively.
Maintenance Tips
- Regular Checkups: Schedule professional maintenance every year to ensure optimal performance.
- Descale: Every six months, flush the system to remove mineral buildup, especially in hard water areas.
- Inspect Filters: Clean or replace air and water filters regularly to prevent blockages and maintain efficiency.
Troubleshooting Common Issues
If you’re experiencing issues like error code 111, consider these steps:
- Check Gas Supply: Ensure your gas line is connected and the supply is uninterrupted.
- Inspect Ignition Components: Look for blockages or failures in ignition components.
- Consult the Manual: Refer to your unit’s user manual for specific troubleshooting steps.
Understanding the features, maintenance, and troubleshooting of AO Smith tankless water heaters helps you maximize performance and efficiency in your home.
Common Error Codes
A.O. Smith tankless water heaters may display various error codes. Understanding these codes helps address issues quickly and efficiently.
Understanding Error Code 111
Error code 111 indicates ignition or gas supply issues. This code can appear when the heater struggles to ignite. Often, it means there’s insufficient gas pressure, a blockage in the gas line, or a malfunctioning ignition component. Inspecting the gas supply and verifying adequate pressure is essential. For instance, check for closed valves or debris that might obstruct the gas flow.
Implications of Error Code 111
Error code 111 affects your hot water supply. Without proper ignition, the heater can’t produce hot water, leading to cold showers. Continuous issues with code 111 can indicate larger problems with your water heater. Ignoring this warning may cause wear on the unit or necessitate costly repairs. Regular maintenance and immediate troubleshooting can prevent these complications, ensuring your heater runs smoothly.
Troubleshooting Error Code 111
Error code 111 signals issues with ignition or gas supply in your A.O. Smith tankless water heater. You can effectively address this code by following a structured troubleshooting approach.
Step-by-Step Troubleshooting Guide
- Check Gas Supply: Ensure gas is available. If you use natural gas, verify that your main valve is open. For propane, check that the tank isn’t empty.
- Inspect Gas Line for Blockages: Look for any blockages in the gas line. Clear any debris or obstructions that might impede gas flow.
- Examine Ignition Components: Inspect the ignition electrode for dirt or damage. Clean it gently or replace it if necessary.
- Test the Power Supply: Confirm there’s power to the unit. Check your circuit breaker and ensure it hasn’t tripped.
- Reset the Unit: Turn off the heater, wait a few minutes, and turn it back on. This action can reset the internal system.
- Consult the Manual: Refer to your unit’s manual for specific troubleshooting steps tailored to your model.
- Contact Professional Help: If the issue persists after these steps, consider reaching out to a qualified technician.
- Screwdriver: Use a screwdriver to open access panels for internal inspection.
- Multimeter: Check for power supply issues with a multimeter.
- Manometer: Measure gas pressure if you suspect supply issues.
- Flashlight: Required to illuminate hard-to-see areas while inspecting.
- Cleaning Brush: Use a cleaning brush to remove dirt from ignition components.
Using these tools and following the steps outlined helps you effectively troubleshoot and address error code 111 in your A.O. Smith tankless water heater.
Preventive Maintenance Tips
Maintaining your A.O. Smith tankless water heater helps prevent error code 111 and ensures efficient operation. Follow these practical tips to keep your system running smoothly.
Regularly Check the Gas Supply
Inspect the gas supply line monthly. Look for any signs of leaks or damage. If you notice low pressure, contact a professional for assistance.
Perform Routine Descaling
Descale your heater every six months, especially in hard water areas. Use a descaling solution to remove mineral buildup. This process improves efficiency and extends the life of your unit.
Clean the Air Filter
Examine and clean the air filter every three months. A dirty filter can restrict airflow, impacting performance. Replace it if it’s too worn.
Inspect Venting Systems
Check the venting system for blockages and proper connections once a year. Clear any debris or obstructions to ensure proper exhaust flow.
Test Safety Features
Regularly test safety features like the pressure relief valve and flame sensor. These components protect your unit from malfunctions. Replace any faulty parts promptly.
Keep Documentation Handy
Maintain your user manual and service records. These documents provide important information, including troubleshooting steps and warranties.
Schedule Annual Professional Inspections
Consider scheduling a professional inspection annually. A technician can identify potential issues before they escalate, saving you time and money.
Implementing these preventive maintenance tips helps you avoid error code 111 and keeps your A.O. Smith tankless water heater functioning efficiently.
Conclusion
Dealing with error code 111 can be a hassle but you’re now equipped with the knowledge to tackle it head-on. By understanding the common causes and following the troubleshooting steps outlined, you can restore your hot water supply and keep your A.O. Smith tankless water heater running smoothly.
Remember that regular maintenance is key to preventing future issues. By taking proactive measures like checking the gas supply and scheduling annual inspections, you can enjoy the efficiency and reliability of your water heater for years to come. Don’t let a minor setback disrupt your comfort—take action and stay warm!
Frequently Asked Questions
What does error code 111 mean on A.O. Smith tankless water heaters?
Error code 111 indicates issues with ignition or gas supply in A.O. Smith tankless water heaters. It typically points to insufficient gas pressure, blockages in the gas line, or malfunctioning ignition components, preventing the heater from igniting properly.
How can I troubleshoot error code 111?
To troubleshoot error code 111, check the gas supply for adequate pressure, inspect the gas line for blockages, examine ignition components, test the power supply, and reset the unit. Refer to the manual for detailed instructions and seek professional help if necessary.
What are the common causes of error code 111?
Common causes of error code 111 include insufficient gas pressure, blockages in the gas line, faulty ignition components, or issues with the power supply. Regular inspections and maintenance can help prevent these problems from arising.
How can I maintain my A.O. Smith tankless water heater?
Regular maintenance for your A.O. Smith tankless water heater includes checking the gas supply for leaks, descaling every six months, cleaning the air filter every three months, inspecting venting systems annually, and scheduling professional inspections to ensure optimal performance.
What tools do I need for troubleshooting error code 111?
Essential tools for troubleshooting error code 111 include a screwdriver, multimeter, manometer, flashlight, and cleaning brush. These tools will assist you in checking various components and effectively addressing the issue.

Jake Newman is Appliance Mastery’s expert on refrigeration and cooling systems. With over a decade of experience in the appliance repair industry and certification from NASTeC, Jake is a trusted source of knowledge for homeowners who want to troubleshoot and repair their fridges, freezers, and air conditioning units.