Every homeowner with a water heater knows the frustration: you turn on the hot water, and nothing comes out but a chilly stream. For those with an AO Smith water heater, this scenario often leads to a search for the reset button. Many believe a simple press will solve all problems. But in reality, the reset button is both a safety device and a signal—if it keeps tripping, something deeper is wrong. Understanding why this happens and how to troubleshoot it can save time, money, and cold showers.
This article explains how the AO Smith water heater reset button works, why it might trip, and how to diagnose and fix common problems. Whether you’re a DIY enthusiast or just want to know when to call a pro, you’ll find actionable advice, practical examples, and real troubleshooting steps. Let’s get your hot water flowing again.
What Is The Ao Smith Water Heater Reset Button?
The reset button on an AO Smith water heater is a built-in safety feature. Sometimes called the “high limit switch” or “ECO” (Energy Cut Off), it’s designed to stop the heater when the water gets too hot. This protects your home from overheating, scalding, and even fire risk.
You’ll usually find the reset button under the upper thermostat cover. It’s a small red button that “pops out” when tripped. Pressing it resets the high limit switch, allowing the heater to operate again—if the underlying problem is solved.
Why Does The Reset Button Trip?
The reset button is not supposed to trip during normal use. If it does, it means:
- The water temperature inside the tank got too high (usually above 180°F).
- There’s a malfunction, such as a broken thermostat, faulty heating element, or wiring issue.
It’s important to understand: repeatedly pressing the reset button is not a fix. It’s a warning sign. Investigating the cause protects your family and your heater.
Common Reasons The Reset Button Trips
Let’s break down the most common reasons your AO Smith reset button activates. Each has its own signs, causes, and solutions.
1. Faulty Thermostat
The thermostat controls water temperature by turning the heating elements on and off. If it fails, it can “stick” in the ON position, causing the water to overheat. The reset button trips to prevent boiling.
Signs:
- Water is extremely hot.
- Reset button trips often after a few hours.
Solution:
- Test and replace the thermostat if needed (more on this in the troubleshooting section).
2. Defective Heating Element
A burned-out or shorted heating element may cause the water to heat uncontrollably or draw too much power, triggering the reset button.
Signs:
- No hot water, or water gets hot then quickly cold.
- Reset button trips after a few minutes.
Solution:
- Inspect and replace faulty heating elements.
3. Loose Or Damaged Wiring
Loose connections or frayed wires can cause electrical surges or shorts. This interrupts normal operation and can make the reset button trip.
Signs:
- Flickering power.
- Scorch marks near wiring.
- Occasional “burning” smell.
Solution:
- Shut off power, check connections, and repair or tighten wiring.
4. Sediment Buildup
Over time, minerals in water settle at the bottom of the tank. This forms a layer of sediment that insulates the heating element, causing it to overheat and trip the reset.
Signs:
- Rumbling or popping noises.
- Slower heating.
- Water heater age above 5 years.
Solution:
- Flush the tank regularly to remove sediment.
5. High Incoming Water Pressure
If the water pressure in your home is too high, it can force the heater to work harder, sometimes causing overheating and tripping.
Signs:
- Hot water leaks from the temperature-pressure relief valve.
- Reset button trips after heavy water use.
Solution:
- Check and adjust the home’s pressure regulator.
6. Faulty Reset Button
Sometimes, the reset button itself fails. Springs inside can weaken, or contacts corrode, making it trip too easily.
Signs:
- Button won’t stay in.
- Trips even when other parts are new.
Solution:
- Replace the reset button or thermostat assembly.
How To Locate And Use The Ao Smith Water Heater Reset Button
Finding and pressing the reset button is simple, but safety is critical. Follow these steps:
- Turn Off Power: Go to your circuit breaker panel and switch off power to the water heater. Never work on a live appliance.
- Remove Access Panel: Use a screwdriver to open the upper thermostat cover. You may need to remove insulation.
- Find the Reset Button: Look for a small red button near the thermostat.
- Press the Button: Push firmly until you feel a “click.” The button should stay in.
- Replace Cover and Restore Power: Put the insulation and cover back, then turn on the breaker.
- Wait and Check: Give the heater 30-60 minutes. Check if hot water returns and if the button stays in.
Tip: If the button immediately pops out again, do not keep pressing it. This means there’s a real problem.
Step-by-step Troubleshooting Guide
If your reset button keeps tripping, follow this guide. You’ll need basic tools and some care. If you’re not comfortable, call a licensed plumber or electrician.
Tools You May Need
- Screwdriver (Phillips and flathead)
- Digital multimeter
- Insulated gloves
- Flashlight
- New thermostat or heating element (if replacement is needed)
Safety First
- Always turn off power at the breaker.
- Use insulated tools.
- If you smell burning or see smoke, call a professional immediately.
Step 1: Inspect The Thermostat
- Remove the upper access panel and insulation.
- Set your multimeter to “continuity.”
- Disconnect wires from the thermostat.
- Place probes on the thermostat terminals.
- If there’s no continuity, the thermostat is bad.
Tip: Both upper and lower thermostats should be checked. Replace any that fail.
Step 2: Test The Heating Elements
- With power off, remove wires from the element terminals.
- Set the multimeter to the ohms (Ω) setting.
- Place probes on each terminal.
- A good element usually reads between 10-16 ohms (check your model).
- If it reads “infinite” (open) or zero (shorted), replace the element.
Step 3: Check Wiring Connections
- Look for loose, burned, or discolored wires.
- Tighten all connections snugly.
- Replace damaged wires.
- Ensure wires don’t touch the tank or other metal parts.
Step 4: Flush The Tank
- Attach a garden hose to the drain valve at the bottom.
- Turn off power and cold water supply.
- Open a hot water faucet in your home (to prevent vacuum).
- Open the drain valve and let water flow until clear.
- Close the valve, refill the tank, and restore power.
Tip: Flushing once a year helps prevent sediment problems.
Step 5: Test Water Pressure
- Use a pressure gauge at a hose bib.
- Normal home water pressure is 40-60 psi.
- If it’s above 80 psi, install or adjust a pressure regulator.
Step 6: Check The Reset Button
If all else fails, the button itself might be bad. Replacement is usually part of the thermostat assembly.
When To Call A Professional
Some repairs are best left to experts. Call a licensed plumber or electrician if:
- The breaker trips along with the reset button.
- You see burned wires or melted plastic.
- There’s water leaking from the heater.
- You’re not comfortable with electricity.
A professional can diagnose complex problems, replace faulty components, and ensure safety.
Preventing Future Reset Button Issues
Most reset button trips can be prevented with regular maintenance and a few smart habits.
Regular Maintenance
- Flush the tank yearly to prevent sediment buildup.
- Check thermostat settings: Keep below 120°F for safety and energy savings.
- Inspect wiring every 6-12 months for signs of wear.
- Test the pressure relief valve every year.
Smart Usage Tips
- Don’t turn the thermostat above 140°F. Higher temperatures increase risk of overheating.
- If your area has hard water, consider a water softener to reduce sediment.
- Fix leaks quickly to avoid water damage and electrical shorts.
Know Your Water Heater’s Age
Most AO Smith water heaters last 8-12 years. If yours is older and reset button problems are frequent, replacement might be cheaper than constant repairs.
Key Differences: Ao Smith Vs. Other Brands
Not all water heaters are built the same. Here’s how AO Smith’s reset button compares to other common brands:
| Brand | Reset Button Location | Thermostat Design | Common Issues |
|---|---|---|---|
| AO Smith | Upper thermostat panel | Separate upper/lower thermostats | Thermostat failure, sediment buildup |
| Rheem | Upper panel, sometimes lower | Integrated control board | Electronic board failure |
| Bradford White | Upper thermostat panel | Single thermostat, some models | Element shorts, wiring issues |
Insight: AO Smith’s simple mechanical design makes DIY troubleshooting easier, but it’s more sensitive to sediment and thermostat problems.
How To Replace A Faulty Ao Smith Reset Button
If you’ve confirmed the reset button (or the thermostat assembly) is faulty, replacing it is a moderate DIY task.
Before You Begin
- Buy the correct thermostat or ECO switch for your AO Smith model.
- Have your model number ready (usually on a label near the bottom of the tank).
Steps
- Turn off power at the breaker.
- Remove the upper access panel and insulation.
- Disconnect the wires from the thermostat.
- Loosen the mounting clips or screws.
- Remove the old thermostat assembly.
- Install the new thermostat, securing it in place.
- Connect the wires exactly as before (take a photo if unsure).
- Replace insulation and panel.
- Restore power and test.
Common Mistakes To Avoid
- Forgetting to turn off power (risk of electric shock).
- Mixing up wire connections (take a photo before removing).
- Installing the wrong thermostat model (check compatibility).
Real-world Example: Troubleshooting Scenario
Let’s walk through a typical case.
Scenario:
John notices his AO Smith water heater reset button trips every two days. He resets it, gets hot water, then it trips again.
Step-by-step:
- He turns off power and opens the upper panel.
- With a multimeter, he tests the upper thermostat—shows no continuity.
- He replaces the thermostat.
- The reset button stays in, and hot water returns.
- Two weeks later, the problem returns. This time, he flushes the tank and finds lots of sediment.
- After flushing, the reset button no longer trips.
Lesson:
Multiple issues can combine—thermostat failure and sediment buildup. Always check both.
Ao Smith Water Heater Reset Button: Quick Troubleshooting Table
Here’s a handy reference for common problems and solutions.
| Problem | Likely Cause | Action |
|---|---|---|
| Button trips after 1-2 hours | Faulty thermostat | Replace thermostat |
| Button trips immediately | Shorted heating element | Replace element |
| Button won’t stay reset | Bad ECO switch or wiring | Replace switch, check wiring |
| Button trips after heavy use | High water pressure | Check/adjust pressure |
| Button trips after years of use | Sediment buildup | Flush tank |
Ao Smith Reset Button Troubleshooting: Data Insights
Recent data from plumbing service calls shows:
- Thermostat failure causes about 40% of reset button trips.
- Heating element problems cause 25%.
- Wiring issues account for 15%.
- The rest are due to pressure, sediment, or a bad ECO switch.
Pro tip: If your AO Smith water heater is under 8 years old, repairs are usually cost-effective. For older units, replacement may be better.
Non-obvious Troubleshooting Insights
- Thermostat stacking: If you set your thermostat too high, the water can “stack,” with extra-hot layers at the top tripping the reset. Keeping the thermostat at or below 120°F prevents this.
- Intermittent wiring faults: Sometimes, wires expand and contract with heat, causing the reset button to trip only after long use. Checking connections when the heater is hot can reveal hidden problems.
Recommended Ao Smith Water Heater Maintenance Schedule
Regular care prevents many reset button trips. Here’s a simple schedule to keep your unit healthy:
| Task | Frequency | Why It Matters |
|---|---|---|
| Flush tank | Yearly | Prevents sediment overheating |
| Check thermostat settings | Every 6 months | Reduces risk of tripping |
| Inspect wiring | Every 6-12 months | Prevents shorts and trips |
| Test pressure relief valve | Yearly | Prevents overpressure |
| Replace anode rod | Every 3-5 years | Extends heater life |
Frequently Asked Questions
Why Does My Ao Smith Water Heater Reset Button Keep Tripping?
The reset button trips when water gets too hot, usually due to a bad thermostat, faulty heating element, wiring problems, or sediment buildup. Repeated tripping is a sign of a real issue—don’t just keep resetting.
Can I Use My Water Heater If The Reset Button Keeps Tripping?
No. If the button won’t stay in, your heater is unsafe or broken. Using it can risk fire, scalding, or electrical damage. Fix the root problem before using hot water.
How Do I Know If My Thermostat Or Heating Element Is Bad?
Test both with a multimeter. A faulty thermostat won’t show continuity, and a bad element will read open or short. Replace any part that fails the test.
Is It Dangerous To Press The Reset Button Many Times?
Yes. The reset button is a safety device. If it keeps tripping, something is wrong. Repeatedly pressing it without fixing the cause can lead to serious damage or accidents.
Where Can I Get Official Ao Smith Water Heater Parts?
Buy genuine parts from AO Smith dealers, reputable hardware stores, or the official AO Smith website. For more technical details, visit the AO Smith official site.
If your AO Smith water heater reset button keeps causing problems, don’t ignore it. With the right troubleshooting, you can restore safe, reliable hot water and protect your home from bigger issues. Regular maintenance and knowing when to call a pro will keep your showers hot and your worries cold.
