Is your AO Smith water heater making strange noises, delivering lukewarm water, or showing signs of rust-colored discharge? You’re not alone. Over time, sediment buildup from hard water can reduce efficiency, shorten tank life, and even cause premature failure. Draining your AO Smith water heater regularly is one of the most effective ways to prevent these issues and keep your system running smoothly.
In this guide, you’ll learn a step-by-step process to safely and completely drain your AO Smith water heater, whether it’s gas or electric. You’ll also discover how often to flush the tank, what tools you need, and common mistakes to avoid so you can extend the life of your unit and maintain peak performance.
Essential Safety Precautions Before Draining Your AO Smith Water Heater
Before touching any components, safety must come first. A water heater contains hot water under pressure, so improper handling can lead to burns, electrical hazards, or gas leaks.
Turn Off Power or Gas Supply to the Unit
For electric models, go to your home’s electrical panel and switch off the breaker labeled “water heater.” Never assume the power is off. Verify it using a voltage tester at the unit’s junction box if possible.
For gas models, locate the gas control knob near the bottom of the unit. Turn it from “Pilot” or “On” to the “Off” position. Wait 5 to 10 minutes for residual gas to dissipate before proceeding.
Shut Off the Cold Water Inlet Valve
Find the cold water supply valve at the top of the water heater. It is usually located on the right-side pipe labeled “cold.” Rotate the handle clockwise until it is fully closed to stop new water from entering the tank.
Let the Water Cool or Proceed with Caution
Ideally, wait 6 to 12 hours after turning off the heater before draining, especially if it was recently in use. Draining hot water can cause scalding and create steam that may damage hoses or flooring.
If you must drain while warm, open a hot water faucet in a nearby sink or tub to relieve pressure and allow air into the system. This reduces the risk of vacuum lock and helps water flow more smoothly during draining.
Prepare Your Drainage Setup
Draining requires directing a large volume of water safely outside or into a floor drain. Planning your route prevents spills and protects your home.
Attach a Garden Hose to the Drain Valve
Locate the drain valve near the bottom of the AO Smith water heater. It resembles a standard outdoor spigot. Connect a standard garden hose securely to this valve.
Pro Tip: Use a brass or reinforced rubber hose rated for hot water. Cheap vinyl hoses can burst under pressure or degrade from hot, sediment-laden water.
Route the Hose to a Safe Drain Location
Run the hose to one of the following:
– Floor drain
– Sump pump pit
– Outside via basement window or door
– Utility sink (only if large enough)
Avoid routing through living areas or over electrical equipment. Ensure the path is free of kinks and downward sloping to allow gravity-fed flow.
Relieve Tank Pressure Before Draining
Even with the cold water off, pressure remains in the system. Releasing it prevents sputtering and allows smooth drainage.
Open a Hot Water Faucet
Go to any nearby hot water tap. A kitchen or bathroom sink works best. Turn it to the “hot” setting and leave it open throughout the draining process.
This introduces air into the system, breaking the vacuum that could otherwise slow or stop water flow from the tank.
Check the Pressure Relief Valve
Locate the temperature and pressure (T&P) relief valve on the top or side of the tank. Lift the test lever slightly to ensure it moves freely. Do not force it.
If water dribbles out, that is normal. If it leaks continuously after release, it may need replacement, but this will not stop you from draining the tank.
Open the Drain Valve and Flush the Tank
Now that the system is depressurized and prepped, it is time to empty the tank.
Slowly Open the Drain Valve
Using a flathead screwdriver or your hand (wear gloves), turn the drain valve counterclockwise. Start slowly. Sediment-laden water may gush or spurt initially.
If no water flows, try wiggling the valve or slightly reopening the cold water inlet for a few seconds to stir sediment and repressurize the top.
Monitor Flow and Clear Clogs
Water should flow steadily. If it slows or stops:
– Close the valve
– Close the hot water faucet briefly
– Reopen cold water inlet for 10 seconds
– Close inlet again and reopen drain valve
This surge can dislodge sediment blocking the outlet.
Warning: Never use pliers to force the valve. It is made of brass and can break. Replace if damaged.
Flush Until Water Runs Clear
Once the tank is mostly empty, briefly open the cold water inlet to stir up remaining sediment. Let the turbulent water flush out through the hose.
Repeat this cycle (refill slightly, then drain) until the exiting water appears clear. This deep flush removes the bulk of mineral deposits.
Close the Drain Valve and Refill the System
After draining, proper reassembly ensures safe operation and prevents airlocks or leaks.
Close the Drain Valve and Detach the Hose
Once flushing is complete, tightly close the drain valve by turning it clockwise. Remove the hose and cap or plug the valve if recommended by your model.
Inspect the valve for leaks. Replace if cracked or dripping.
Reopen the Cold Water Supply
Slowly turn the cold water inlet valve counterclockwise to restore flow. Do this gradually to avoid water hammer, a loud banging caused by sudden pressure changes.
As the tank refills, listen for gurgling at the open hot water faucet. This indicates air escaping.
Restore Power or Ignite the Pilot
Wait until water flows steadily from the open faucet with no air sputtering. This confirms the tank is full.
For electric models, switch the breaker back on.
For gas models, follow the relighting instructions on the unit’s label:
1. Set control knob to “Pilot”
2. Press and hold reset button
3. Use igniter or match to light pilot flame
4. Hold for 30 seconds, then release
5. Turn knob to “On”
Recommended Maintenance Schedule for Your AO Smith Water Heater
Regular draining prevents long-term damage and maintains efficiency.
Flush Every 6 to 12 Months
AO Smith recommends flushing your water heater at least once per year. In areas with hard water (high mineral content), every six months is ideal.
Signs you need to flush sooner:
– Popping or rumbling sounds
– Reduced hot water supply
– Longer heating cycles
– Rust-colored water
Extend Tank Longevity with Routine Care
Flushing removes corrosive sediment that accelerates rust and overheats heating elements. Units maintained annually can last 2 to 5 years longer than neglected ones.
Pair flushing with anode rod inspection every 2 to 3 years for maximum protection.
Troubleshooting Common Draining Problems
Even with careful prep, problems can arise during draining.
No Water Flow from the Drain Valve
Possible causes include:
– Closed cold water inlet
– Vacuum lock (fix by opening hot water tap)
– Sediment blockage
– Faulty drain valve
Try the refill-and-flush method first. If still blocked, consider replacing the drain valve or using a wet/dry vacuum to initiate suction.
Leaking Drain Valve After Closing
A small drip may stop as the washer reseats. Persistent leaks mean:
– Debris trapped in valve seat
– Worn internal washer
– Cracked valve body
Replace the valve if leaking continues. AO Smith offers replacement valves compatible with most models.
Pilot Will Not Stay Lit on Gas Models
After draining, air in the gas line may interfere with ignition.
Steps to resolve:
– Ensure gas valve is fully open
– Repeat ignition process, holding pilot button longer
– Check for draft issues in vent pipe
– Call technician if problem persists
Upgrades for Easier Maintenance
Some newer AO Smith models come with features that simplify draining.
Replace the Standard Drain Valve with a Ball Valve
Standard drain valves can corrode or seize. Replace with a full-port ball valve for smoother operation and better durability.
Install it during annual maintenance using pipe tape on threads for a leak-proof seal.
Install a Drain Pan with Overflow
If your water heater is in an attic or upstairs closet, place a drain pan underneath connected to a discharge pipe. This protects flooring and allows safer indoor draining.
Consider Tankless or Hybrid Models
For future upgrades, AO Smith’s tankless or heat pump water heaters require less sediment maintenance. While not immune to scale, they offer easier self-cleaning modes and longer service intervals.
Frequently Asked Questions About Draining an AO Smith Water Heater
How Often Should I Drain My AO Smith Water Heater?
AO Smith recommends draining at least once per year. In hard water areas with high mineral content, flush every six months to prevent sediment buildup and maintain efficiency.
Can I Drain My AO Smith Water Heater Without Turning Off the Gas?
No. You should always turn the gas control knob to “Off” and wait 5 to 10 minutes before draining. This prevents fire hazards and allows residual gas to dissipate safely.
What Happens If I Do Not Flush My Water Heater Regularly?
Sediment accumulates at the bottom of the tank, causing popping noises, reduced heating efficiency, longer recovery times, and eventual corrosion. Neglected units may fail years earlier than well-maintained ones.
Is It Safe to Drain a Water Heater by Myself?
Yes, if you follow safety precautions. Turn off power or gas, shut off the cold water supply, and allow the water to cool. Use proper hoses and avoid forcing any valves.
How Long Does It Take to Drain an AO Smith Water Heater?
Draining typically takes 30 to 60 minutes, depending on tank size and sediment level. Adding a deep flush cycle may extend the process by another 15 to 20 minutes.
Do I Need a Professional to Drain My Water Heater?
Most homeowners can complete this task with basic tools. However, if you encounter a faulty valve, persistent leaks, or gas ignition problems, contact a licensed plumber or technician.
Key Takeaways for Draining Your AO Smith Water Heater
Draining your AO Smith water heater is a simple yet powerful way to boost efficiency, prevent breakdowns, and extend service life. Always prioritize safety by turning off power or gas, shutting off the cold water supply, and allowing the tank to cool before draining.
Flush the tank annually, or every six months in hard water areas, to remove sediment that causes noise, corrosion, and reduced performance. Use a quality hose, route water to a safe drain, and flush until water runs clear for the best results.
Set a reminder to inspect your anode rod every 2 to 3 years and consider upgrading to a ball valve for easier future maintenance. With a little time and care, your AO Smith heater can perform like new for years to come.
