A.O. Smith Water Heater Heating Element Replacement Guide — What This Part Does
The electric heating element is the component that converts electrical energy into heat inside your A.O. Smith water heater tank. Most residential electric tanks have two elements (upper and lower) that work in sequence to heat the full volume of water. When an element burns out or fails electrically, the tank stops heating at that location. You may lose all hot water if the upper element fails, or experience slow recovery and lukewarm water if the lower element quits. Elements fail over time from normal use, mineral buildup on the element surface, or electrical stress. A.O. Smith replacement procedures focus on removing the defective element and installing a new one with a fresh gasket and correct electrical connections to restore the heater’s full heating capacity.
Signs It Needs Replacing
- No hot water at all The tank produces no hot water even after several hours of standby, which typically means the upper element has failed.
- Only lukewarm water or slow recovery You get a small amount of hot water that runs out quickly and the tank takes much longer than usual to reheat, pointing to a failed lower element.
- Hot water only from the top of the tank The first gallon or two is hot but then turns cold immediately, meaning the upper element may work but the lower element does not.
- Breaker trips repeatedly The circuit breaker trips when the water heater tries to heat, which can indicate a shorted or grounded element that must be replaced.
- Visible corrosion or burn marks at the element terminals Inspecting the element access panel reveals corroded, discolored, or burned wire connections at the element, showing the element or its connections have failed.
- Element tests open or shorted with a multimeter Testing the element for continuity (with power off) shows infinite resistance (open circuit) or zero resistance to ground (short), confirming the element is electrically failed.
How to Replace It
- Shut off power to the water heater at the circuit breaker and verify it is de-energized before starting any work.
- Turn off the cold water supply valve to the heater.
- Open a hot water faucet somewhere in the house to relieve pressure in the tank and help the tank drain.
- Attach a garden hose to the drain valve at the bottom of the tank and run the hose to a floor drain or outside, then open the drain valve and drain the tank completely for a lower element replacement or partially (below the element level) for an upper element replacement.
- Remove the access cover panel, pull out the insulation, and remove the plastic safety cover over the element and thermostat (if present), then take a photo or note which wire connects to which terminal on the element before disconnecting them.
- Disconnect the two wires from the element terminals, then use a heating element wrench or 1-1/2 inch deep-well socket to unscrew and remove the old element from the tank, making sure the old gasket comes out with it and cleaning any residue from the tank threads and sealing surface.
- Confirm the replacement element matches your heater by checking the data plate or serial number on the tank and using A.O. Smith’s part lookup or purchasing the OEM replacement element with the correct wattage and voltage for your model.
- Place the new rubber gasket on the replacement element and apply a small amount of dish soap to the gasket as a lubricant to prevent tearing, then hand-start the new element straight into the tank opening (do not cross-thread) and tighten it securely with the element wrench or socket.
- Reconnect the two wires to the terminals on the new element and make sure all connections are tight and secure, then reinstall the plastic safety cover, insulation, and access panel.
- Close the drain valve, remove the hose, and open the cold water supply valve to refill the tank, letting the hot water faucet run until water flows steadily with no air sputtering (this confirms the tank is full), then close the faucet.
- Restore power at the breaker only after the tank is completely full, then wait 30 to 60 minutes and test for hot water at a faucet.
The Part You Need
| Part | Notes |
|---|---|
| Electric water heater heating element (screw-in or flange type) | Amazon | Match the wattage, voltage, and style (screw-in or flange mount) to your heater. Find your exact model and serial number on the data plate label on the side of the tank and use A.O. Smith’s serial-number-based part lookup or cross-reference to identify the correct OEM replacement element for your unit. |
| Heating element gasket | Amazon | Often included with the replacement element. Always use a new gasket when installing a new element to prevent leaks at the seal. |
Related Error Codes
If this part is failing you may also see one of these codes:
- A O Smith Water Heater E2 error code
- A O Smith Water Heater E4 error code
- A O Smith Water Heater E6 error code
When to Call a Pro
If you are not comfortable working with 240-volt electrical connections, or if you replace the element correctly but the heater still does not produce hot water, call a licensed technician. The problem may be a failed thermostat, a tripped high-limit switch, or a wiring or breaker issue upstream of the element. A technician can test the thermostats, check for voltage at the element, and diagnose whether the tank itself has internal failures that would require full replacement rather than just an element swap. For gas line, burner, or igniter work, or if you ever smell gas, stop and call a licensed technician.