There are several possible reasons why your electric water heater may not be heating water properly or at all. Identifying the underlying cause is key to getting your hot water heater up and running again.
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1. No power to the water heater
The most obvious issue is if the water heater has no power supply. Check the following:
- Make sure the water heater is plugged in and the outlet has power. Try plugging something else into the outlet to check.
- Check the circuit breaker or fuse box to ensure the circuit for the water heater has not tripped. Reset any tripped breakers.
- Inspect the wiring connections to the upper and lower heating elements to ensure they are intact. Loose or corroded connections can prevent power from reaching the elements.
If there are issues with the power supply, you will need to address those before the water heater can heat up again. Electrical issues should be handled by a licensed electrician if you are not experienced with electrical repairs.
2. Failed heating element
Electric water heaters have two heating elements – an upper and lower. One or both elements may have failed, preventing the water from heating properly. Here’s how to check the heating elements:
- Turn off power to the water heater at the circuit breaker.
- Drain some water out of the tank so the elements are exposed.
- Remove the access covers over the upper and lower elements.
- Visually inspect the elements for signs of damage. Look for cracks in the metal sheath or ceramic insulator.
- Use a multimeter to check for continuity through the element. No continuity means it is broken.
If one or both elements are not working, they will need to be replaced. Be sure to use replacement elements with the same voltage, wattage, and connector type.
3. Thermostat failure
The thermostat controls power to the heating elements, telling them when to turn on and off to maintain the set temperature. If the thermostat malfunctions, the elements will not heat the water properly. Here’s how to test the thermostat:
- Turn off power to the water heater.
- Remove the access panel over the thermostat.
- Visually inspect for any signs of damage like discoloration or loose wires.
- Use a multimeter to test for continuity across the thermostat terminals when set to different temperatures.
If there is no continuity when there should be, or vice versa, then the thermostat likely needs to be replaced. Install a replacement thermostat with the same temperature range and electrical specifications.
4. Sediment buildup
Over time, scale and sediment can accumulate at the bottom of the water heater tank. This buildup can cover the lower heating element, insulating it from the water. Flushing the water heater can clear out this sediment buildup:
- Turn off power to the heater and shut off the cold water supply.
- Connect a garden hose to the drain valve and route it to a drain or outside.
- Open the drain valve and allow water to flow until it runs clear.
- Close drain valve and refill tank before restoring power.
Annual water heater flushing helps maximize efficiency and extend the life of your heater.
5. Faulty thermostatic mixing valve
Some electric water heaters have a mixing valve on the outlet to prevent scalding by mixing in cold water. If this thermostatic valve fails, it can reduce the hot water temperature. Inspect the mixing valve for the following issues:
- Check valve settings to make sure it is not set too low.
- Remove and inspect the valve screen filter for debris and clean if dirty.
- Check the valve cartridge for signs of wear, scale buildup, or damage. Replace cartridge if needed.
Replacing the faulty mixing valve should restore proper hot water supply.
6. Leaks in plumbing
Leaks or excessive hot water use can deplete the hot water faster than the heater can heat it. Inspect pipes, fittings, valves, and faucets for any drips or leaks. Look for:
- Wet spots on pipes or drips from fittings/valves.
- Visible corrosion on copper pipes.
- Discolored or soaked drywall/insulation around pipes.
- Increased humidity or moisture in areas with plumbing.
- Higher than normal water usage on your meter.
Repairing any leaks or dripping faucets can allow the water heater to keep up with demand. Consider adding insulation around hot water lines to reduce standby heat loss.
7. Insufficient recovery time
If your water heater is too small for your needs, it may not be able to keep up during periods of heavy water usage. Insufficient hot water supply during showers, running the dishwasher, or using multiple fixtures at once indicates the heater is too small.
Check the first hour rating or recovery rate of your water heater to make sure it is adequate for your household. Upgrade to a larger heater if needed.
Conclusion
An electric water heater not heating is usually due to one of these common problems. Start by checking for power issues, heating element failure, or thermostat malfunction. Sediment buildup, faulty valves, leaks, or an undersized heater can also prevent hot water production. With some troubleshooting and testing, you should be able to determine the cause and remedy the issue.