Common hot water heater problems and solutions

Suddenly no hot water
All of a sudden, the homeowner wants to take a shower or wash the dishes, and the hot water is not available.
 

The high limit may have tripped in the breaker box. If so, turn off power to the tank. Then, remove the cover from the upper element port on the tank. Take out the insulation, remove the cover to the element assembly, and then press the red reset button.
If the red reset button doesn’t work, then there is a problem with the electrical supply. Either the high limit is damaged or the electrical feed is insufficient. Use a volt-ohm meter to test the electrical supply.
If the compartment inside the upper element port on the tank is wet, then it is time to purchase a new hot water heater.
There may be a problem with the thermostat either on the top or on the bottom on the tank. Either replace the thermostat or hire a licensed technician to replace the thermostat(s).
If simple repairs do not solve the problem, there could be greater electricity issues within the home. It is highly recommended then to hire a licensed electrician to evaluate the home’s service and to provide the repair work.

Circuit breaker repeatedly trips the fuse
The circuit breaker connected to the hot water tank continues to trip.

Most hot water heater tanks need two 30 amp breakers and run at 230 volts. If the tank is not connected to the breaker box as such, the circuit breaker could continue to trip. Hire a licensed electrician to rewire the tank’s power supply.

Pilot light blows out frequently

Hire a professional serviceman to evaluate whether or not the thermocouple is faulty. The thermocouple is a safety device that shuts off the gas if the pilot goes out. If the thermocouple is faulty, it will shut off the pilot light frequently without cause.
Investigate whether or not the pilot light is being blown out by drafty streams of air within close proximity to the hot water tank. If needed, install a downdraft hood on top of the tank and a pilot-light baffle below near the pilot light to protect the flame from blowing out.
Sometimes power ventilation equipment located nearby could cause the pilot light to blow out. If the hot water heater shares ventilation tubing with equipment that has power ventilation, then install its own separate ductwork to ensure that the hot water heater gets a dedicated supply of combustion air.
The pilot line could be clogged. It will need to be cleaned by a licensed professional.
Lastly, the control valve could be faulty. It will need to be replaced.

Gas-fueled tank hot water heater safety 101
Review some ideas about how a homeowner can ensure the gas-fueled storage hot water heater is safe from an explosion.

Raise the hot water tank unit 18" from the floor to prevent the ignition of gasoline vapors that collect near the floor.
Yearly, inspect the flue for breaks or gaps that could leak gas.
Hire a service technician to check the temperature pressure-relief valve to make sure it is open and functional.
If the home is within a seismic zone, install an automatic gas shutoff valve that stops the flow of gas in the event of seismic movement.

Anode rod
During the yearly maintenance for the hot water storage tank, the homeowner notices that the anode rod is less than 1/2" thick or fully coated with calcium.

The sacrificial anode rod will need to be replaced. Purchase a magnesium anode rod replacement, wrap its threads with plumbing thread seal tape, and insert the rod into the tank. Ensure the rod is tightened securely.

Tank is leaking
Water is found leaking from the tank itself.
 

Install or replace the pressure valve if the tank does not already have one or if it is broken.
The tank’s temperature could be too high and is therefore causing the water to be under high pressure. Reduce the temperature to 130°F.

 

Leaking water valve
The valve at the bottom of the hot water heater tank used for flushing the tank is leaking.

Replace the flushing valve.
An economical alternative includes purchasing a zinc cap, attach a hose washer onto it, and then screw it onto the valve. The zinc cap and hose washer may stop the drip if screwed on tightly.
 

The tank makes noises
The hot water heater tank is making peculiar noises.

Sediment may have accumulated in the tank enough to make sounds as it rolls around at the bottom of the tank. If this is the case, flush the tank using a garden hose and the flush valve. Beware, however, that beginning to flush a hot water heater tank if not done yearly may inadvertently cause the tank to deteriorate more quickly.

Smelly water
The hot water tank’s water smells foul like that perhaps of rotten eggs.

The smell is most likely caused by anaerobic bacteria. However, if both the cold and hot water smell foul, the water supply may have sulfur.
To kill the anaerobic bacteria, turn off the cold water valve to the water heater and open a hot faucet somewhere in the home to relieve pressure. Drain the water from the tank; open the plumbing on one side and dump in a few pints of hydrogen peroxide. Close up the tank, turn on the cold water valve again, and let some water run from all the spigots and taps throughout the home. (Take care to not add chlorine bleach to the tank instead of hydrogen peroxide.)
In any event, do not replace the magnesium sacrificial anode rod with an aluminum anode rod. Also, make sure to keep the magnesium anode rod in place to prevent premature tank corrosion.

Water too hot
The hot water is too hot. It may have caused a burn.

Reduce the hot water heater temperature to 130°F. (If set to a lower temperature, legionella bacteria may start to grow.) A flathead screwdriver will be needed. Some tanks’ thermostats cannot be changed without first shutting off its power supply.
Turn the thermostat to its lowest setting or to its vacation setting if planning to be away for at least three days.

Water too cold
The water coming from the hot water tank and the hot spigots is not hot enough.

The hot water heater’s thermostat is set to vacation mode or is set below 120°F.
Press the reset button on the high-temperature cut-off.
The hot water tank’s heating element needs to be replaced.
The hot water heater’s pipes need to be insulated. Add self-sticking 3/8"-thick foam pipe insulation that matches the pipes’ diameter to all accessible hot water supply pipes.
Check to see if the high limit switch button has tripped. It is possible the fuse has blown. If so, this circuit breaker will need to be repaired immediately. The circuit breaker wiring may need to be replaced by a licensed electrician.
One or more thermostats may be faulty and need to be replaced.
Verify whether or not the dip tube is split or broken. If it is, then the cold water will mix with the hot water at the top of the tank where the water leaves to go to each point of use. Replace the dip tube if needed.

Lack of enough water
The hot water tank does not provide enough hot water for the household’s needs.

Begin by evaluating whether or not the hot water heater tank is large enough for the demand or whether the gpm of the tankless heater is sufficient for the home’s cold water temperatures and hot water demand. If needed, replace the tank or the tankless heater with a unit that can handle the hot water load.
Sometimes a gas-fueled hot water heater heats water more quickly than an electric-fueled unit. Consider making the change now or plan for the gas-fueled tank or tankless unit for the next time the hot water heater is replaced.
The distance the hot water tank is located from each point of use could be the problem. If there are long pipes, it may take awhile for the existing water to drain from all the pipes until the hot water reaches each point of use. Either relocate the hot water heater to a closer location or install a pump- or gravity-fed recirculation system to keep the water circulating in the piping all the time. Recirculation systems may be expensive.
Verify whether or not the dip tube is split or broken. If it is, then the cold water will mix with the hot water at the top of the tank where the water leaves to go to each point of use. Replace the dip tube if needed.

Heater won’t turn off
The hot water heater storage tank will not turn off and is constantly reheating the water.

Take care immediately to turn off the power supply to the heater at the circuit breaker location. This hot water heater storage tank needs to be replaced with a new model.

Ventilation issues
The end of the ventilation tube is black and sooty.

Quickly hire a professional plumber to clean the ventilation pipe. Make sure the furnace does not share a vent with the hot water heater and other appliances and equipment.

Rusty tank
The hot water storage tank has rust on the tank.

The hot water heater needs to be replaced.