AO Smith Water Heater Maintenance Checklist

Hot water is one of the most important utilities in any commercial space. Regular maintenance is essential for keeping an AO Smith water heater operating efficiently and preventing more time-consuming repairs. Use this AO Smith water heater maintenance checklist to help keep commercial water heating systems in top condition.

Why Preventive Maintenance Matters for AO Smith Water Heaters

Commercial water heaters work hard every day, especially in restaurants, cafeterias, catering facilities, healthcare kitchens and other foodservice environments where hot water demand remains high throughout the day. Proper maintenance helps ensure reliable operation, maintain efficiency, prevent nuisance shutdowns and identify developing component failures before they impact customers. Routine service also helps technicians identify:

• Restricted combustion air
• Venting issues
• Dirty burners
• Water flow restrictions
• Gas supply problems
• Freeze protection concerns
• Error code conditions requiring corrective action

These inspections are especially important in commercial kitchens where grease, dust and airborne contaminants can affect equipment performance.

AO Smith Water Heater Maintenance Checklist

1. Isolate Utilities Before Service

Before performing maintenance:

• Turn off electrical power to the unit.
• Close the manual gas shutoff valve.
• Close the manual water control valve.

2. Clean the Cold Water Inlet Filter

The inlet filter should be inspected and cleaned as part of routine maintenance because debris accumulation can restrict flow and affect heater performance. Inspection points:

• Remove and inspect inlet filter assembly.
• Check for sediment, scale or debris buildup.
• Clean thoroughly before reinstalling.
• Inspect O-rings and sealing surfaces for damage.

For units operating in areas with hard water or poor water quality, more frequent filter inspections may be necessary. Follow the bottom section of this guide for draining and cleaning the filter. 

3. Inspect Combustion Air Openings

Verify that all combustion and ventilation air openings remain unobstructed. Restricted airflow can impact burner performance and combustion quality. Look for:

• Dust accumulation
• Kitchen grease
• Packaging materials
• Stored items near the appliance
• Damaged air intake components

In restaurant environments, grease-laden air can be particularly problematic and should be addressed before it affects combustion operation.

4. Inspect the Venting System

The venting system should be checked annually for a variety of problems. A compromised vent system can affect combustion performance and create safety concerns. Here is a checklist to go through during annual inspections:

• Vent leaks
• Corrosion
• Blockages
• Loose joints
• Physical damage
• Improper support
• Termination obstructions

5. Inspect and Clean the Burner Assembly

Commercial kitchens often expose equipment to airborne grease and particulates that can accumulate inside the combustion compartment. Inspect the burner assembly annually for debris like dust, dirt, lint or grease. Make sure to perform the following annually:

• Inspect burner surface condition.
• Remove debris and contamination.
• Check for excessive discoloration.
• Verify proper ignition sequence.
• Inspect surrounding combustion components.

6. Verify Burner Flame Quality

You should visually inspect burner flames through the burner viewing window during your maintenance inspection. Normal burner functions have a stable flame and blue color. Burner malfunctions look like the flame lifting above the burner or a yellow or red color.  

7. Review Error Code History

Before leaving the site, review any displayed fault codes or operational history. Common areas associated with fault conditions include:

• Ignition issues
• Flame failure
• Airflow problems
• Temperature sensor faults
• Water flow issues
• Communication faults in Easy-Link systems

Technicians should document all active and historical codes in the service record.

Water Heater Draining and Filter Cleaning

Draining and filter cleaning are another essential

• Step 1. Close the manual gas shutoff valve.
• Step 2. Turn off power to the unit and wait a couple of seconds. Turn the unit on again.
• Step 3. Wait 30 seconds, then turn off power to the unit.
• Step 4. Close the inlet water valve.
  • Note: If the heater is part of an Easy-Link or Multi-Unit System, close the inlet and outlet water valves to isolate the heater. Then proceed to step 6.
• Step 5. Open all hot water taps. When the residual water flow has stopped, close all the hot water taps.
• Step 6. Place a bucket or pan under the unit’s drain plugs. If isolation valves are installed, open the drains to drain the water. If valves aren’t installed, unscrew the two drain plugs. 
• Step 7. Wait a few minutes for all the water to completely drain from the unit.
• Step 8. Check the water filter located within the cold inlet. With a tiny brush, clean the water filter of any debris and reinsert the filter.
• Step 9. Securely hand tighten the drain plugs back into place.