Electrical Questions? Ask an Electrician Online.

Ask an Expert, Get an Answer ASAP!

Troubleshooting Water Heaters

Water heaters come in three different types, electric, gas and tankless. Electric and gas water heaters look similar in appearance; they are both insulated metal cylinders made to heat and store water. The difference is how the water is heated.

A tankless hot water heater is a new type that provides a continuous supply of hot water on demand. Very small units that have few advantages versus the old tank water heaters. They are compact and save space since they can fasten securely on a wall. These units have no tank reserve and instead they have a radiator type copper coil that is exposed to a burner that only ignites when it senses that water is needed.

An electric water heater has two heating elements, one at the top of the cylinder, the other at the bottom, where a gas water heater has gas burners. They also share many of the same problems when something does go wrong. Therefore, most issues are the same for both electric and gas water heaters.

In general, a hot water heater is one of the most reliable appliances, but when they do have problems, it may be a costly fix. Below we have given you some tips on how to troubleshoot water heaters yourself, to help save time, money and assist in determining if you need an Expert. 

Before troubleshooting an electric water heater; always turn off the main power source at the breaker.

Electric water heater troubleshooting

If an electric water heater does not heat water, it is usually one of three things.

  1. Lack of power because of a blown fuse or tripped breaker. Check the breaker that belongs to the hot water tank and make sure it is set to the “ON” position. If you do not have a breaker, check the fuse box for a blown fuse to the hot water tank and replace if needed
  2. Lack of power to the water tank thermostat. Check to make sure the thermostat is getting an adequate electrical supply with a voltage meter. If the thermostat is getting power, but not producing hot water; try replacing the thermostat.
  3. Test the upper heating element to see if it has electric. If electricity is not the problem, the thermostat may faulty and may need to be replaced.  

Water temperature is fluctuating

If the water is not only warm, this could mean that the water tank heater is too small for the home or structure.

Check to make sure the temperature is turned high enough.  

If the water temperature is set correctly make sure the hot and cold plumbing is properly installed, if not, it could reduce the temperature of the water. To check this, turn off the water going into the water heater. Then, turn on the hot water faucet located on the lower portion of the water tank. If water comes out, then the pipes were not installed correctly.

If the water is too hot or scalding, the temperature control settings are set too high. To fix this, locate the knob and turn it down to the desired setting.

Water heater tank or pipe leak

A loose, rusted, stripped, or corroded gaskets and bolts can often cause a water heater leak.

Sometimes the temperature and pressure relief valve can overheat or become stuck; which can cause enough pressure to cause a leak.

Start troubleshooting a leaky water heater by placing a bucket under the temperature pressure relief valve.  Turn down the thermostat and open the valve to release the pressure or debris. If the valve still leaks, replace the valve.

If the leak is coming from a connecting point such as a pipe fitting or elbow, try tightening the connections. Be sure not to over-tighten, it could cause the threads to strip.

If the leak seems to be coming from the heating element, try tightening the bolts holding the heating element in place. If it still leaks, remove the heating element, and replace the gaskets and bolts.

If there is a hole in the reservoir, it could be caused by corrosion and may need to be replaced.

Rusty colored or foul smelling water

Both electric and gas water tanks have what is called a sacrificial anode rod made of dissolvable magnesium. They are made dissolvable to prevent rust from forming inside the water heater tank. If the anode rod has dissolved, it can cause a leak.  

The sacrificial anode rod can start to produce a rotten egg smell if it becomes decayed and transfer into the water supply.  To fix this, drain the water tank and run two pints of peroxide through the water intake lines. Let the peroxide sit in the tank for approximately two hours. If this still doesn’t take care of the smell, replace the anode with a zinc-alloy anode. If the problem persists after replacing the anode, you may have to replace the water heater.

Water heater makes noise

Both the electric and gas water tank can make strange noises at times, like popping, whining or rumbling. These noises are almost always from the water overheating and boiling within the tank because of sediment that could be in the bottom of the tank. To clean the tank and minimize noise, drain the water from the tank to help remove any sediment and debris that has become trapped.

Troubleshooting a Gas Water Heater

While gas water heaters use fuel to heat the water, they still have components that are powered by electric. Before troubleshooting a gas water heater, make sure to turn off the power at the breaker or fuse box. Also, turn off the gas, and water supply to the water heater.

No Hot Water

When there is no hot water, it is generally due to three things, the pilot flame has blown out, it is not getting sufficient gas supply, or there is a problem with the thermocouple.

First, check the pilot light. If the pilot is out and has plenty of gas, you will smell the gas.  Disable the gas, until the smell is no longer detectable. Turn the gas on and relight the flame.

 If the pilot control valve or thermocouple is loose or stripped, it will need to be tightened or replaced. If it has become stripped, it will need to be replaced.

Gas Water Tank Not Producing Enough Hot Water

Like an electric water heater, a gas water heater must be the right size to supply enough water to the home. If the water heater is too small, it will not be able to provide enough hot water.

Sometimes the problem lies within installation error. Check the hot, and cold pipes were installed correctly and not crossed during installation. If they were, this could hinder hot water production.

Troubleshooting a tankless water heater

Sediment is one of the main reasons a tankless water heater malfunctions.  Accumulation of sediment deposits in the heating elements can interfere with the transfer of heat to the water. When the sediment gathers around the heating element, it acts as an insulator and can cause insufficient hot water problems.

Sediment accumulation also accounts many times for low hot water pressure.

If sediment builds up in the activation system, it can cause the water to heat continuously and irregularly and can damage the heating elements, the SCRs or triacs, and ultimately trip the thermostat to protect the water heater further damages.

It is recommended to install a sediment filter to protect and prolong the life of the tankless water heater.

Not heating water

Verify that you have power to the unit by checking the standby light. Check the circuit breaker if the standby light is not on.

If there is power to the unit, but the lights do not come, it might be time to replace the water heater.

Not hot enough or too hot

If the water is not hot or not as hot as it had been, consider whether the groundwater temperature has dropped. Sometimes, in colder weather, the groundwater temperature, has cooled 5 to 15 degrees, resulting in a lower output temperature. It is suggested to set the temperature to the medium setting during the hot months and increase the heat in cold months to offset the cooler groundwater.

A water heaters power rating will vary with the amount of heating elements inside them and the power rating of those elements. A tankless water heater contains one to four heating elements. If one of the elements break, the water heater will continue working, but its heat capacity can reduce. That can cause the water heater to put out warm water.

If the water heater is not the appropriate size for the application, it is being used; this will affect the temperature of the water as well. If a tankless water heater designed for two bathrooms is installed in a three bathroom home, it will not provide consistant temperature.


It is normal to hear the flow switch click on and off when the flow of water stops and starts.  

If you are still having water heater issues after troubleshooting these common problems, you may need outside Expert help.  Ask an Expert to get the answers you need. 


Please type your question in the field below

3 verified Electricians are online now

Electricians on JustAnswer are verified through an extensive 8-step process including screening of licenses, certifications, education and/or employment. Learn more


Master Electrician

Working on MBA

1425 positive reviews

Service Technician

Associate Degree

3937 positive reviews
Mike G.

Master Electrician

Vocational, Technical or Trade Scho

7539 positive reviews
See all Electricians
JustAnswer in the news:
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
Web sites like justanswer.com/legal
...leave nothing to chance.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.