Troubleshooting and Repair of a Standard Electric Water Heater

 

No Hot Water

 

It may take several hours for a newly installed electric water heater to reach normal operating temperature. If you don't have hot water after two hours (water not even warm), first check to make sure the water heater is getting electrical power. Not getting power is a common reason new water heaters don't work.

Checking for Electrical Power

You can check for power with a simple "circuit tester," but for a more complete diagnosis of electrical problems, you'll need a meter that measures voltage.

To check for power, turn the circuit breaker marked "water heater" off (or remove fuses). Remove the water heater's upper access panel. Carefully remove the insulation and plastic cover. Identify the power supply wires. Usually, these connect to the top two screws of the upper thermostat. Turn the circuit breaker back on and check for voltage on the top two screws of the upper thermostat.

The label on the water heater indicates what voltage the water heater requires. Most residential units are 220/240 volts (but some are 110/120 volts). Verify your water heater is getting the correct voltage. If it is not getting the required voltage, there are probably issues with your home's electrical system. A qualified electrician may be needed to fix your electrical problem. Turn the circuit breaker off, replace the plastic cover, insulation and access panel.

Testing Thermostat for Power with Voltmeter

If the unit is powered with the correct voltage, and still does not produce any hot water, the upper heating element has probably burned out. A water heater must be completely full of water before electric power is applied or the upper heating element will burn out (this is called Dry Fire). The Installation Instructions require that a hot water faucet be opened and the hot water allowed to run full for at least three minutes before turning the power on. This is to make sure all of the air has been removed from the tank, and the tank is completely full of water. If the upper element has burned out, it can be replaced. Replacement heating elements are inexpensive and widely available. After the heating element has been replaced, make sure the tank is completely full of water before turning the power back on.

Some Hot Water, but Not Enough (New Installation)

If a new water heater produces some hot water, but not as much as you're used to or not as much as you need, the thermostats may need adjusting. The Installation Manual has temperature adjustment instructions for your unit as well as important safety information about scalding. Water heater manufacturers recommend a temperature setting of no higher than 120ºF. Higher temperatures increase the risk of scalding injuries. Read and follow the temperature adjustment instructions and safety notices in the Installation Manual that came with your new water heater. Remember, higher temperatures (above 120ºF) can cause serious injuries.

Another possibility is that the water heater is not getting the correct voltage (see Checking for Electrical Power above). It is also possible that the water heater is too small or that your usage has increased.

Water Leaks

With a new water heater, most leaks are caused by leaking connections at the hot water outlet or cold water inlet. Occasionally, leaks can be found coming from a fitting (such as around the Temperature and Pressure Relief Valve) or around one of the heating elements. Leaking fittings can often be tightened or repaired. It is extremely rare for a new tank to leak.

Water Drips

If drips are noticed coming from the discharge pipe of the Temperature and Pressure Relief Valve, the home's water pressure may be too high or a thermal expansion tank may be needed.

Note - If large quantities of hot water are coming from the discharge pipe, turn electrical power off and consult a qualified technician. Do not cap or plug the discharge pipe.

Water Pressure

Check your home's water pressure with a gauge. The recommended water pressure is 50 to 60 PSIG. If the pressure is higher than that, install a Pressure Regulating Valve (or adjust your existing pressure regulating valve if you have one). For water pressure issues, consult your local water utility or a qualified plumber. Most plumbing codes require a Pressure Regulating Valve if the water pressure is above 80 PSIG.

Thermal Expansion Tank

When water is heated, it expands. In older homes, the expanded water pushed back into the water main. Today, most homes have backflow prevention valves which stop the water in your home from reentering the water supply. These valves can be inside water softeners, pressure regulating valves or the water meter itself. Backflow prevention valves (also known as "check valves") prevent the expanded water from reentering the water main. Since the expanded water now has nowhere to go, the water pressure in the house's pipes can increase dramatically, often to the point where the Temperature and Pressure Relief Valve discharge pipe drips. A thermal expansion tank has an internal air bladder which can absorb the expanded water, protecting plumbing, appliances and the water heater. For these reasons, most homes now need a thermal expansion tank (and a properly adjusted pressure regulating valve). Not having a thermal expansion tank is the most common reason for a dripping discharge pipe.

WARNING! Do Not Cap or Plug the Temperature and Pressure Relief Valve Discharge Pipe. Explosion Hazard.