Troubleshooting Water Heaters: Common Problems and a Repair Guide

If you’re having issues with your water heater, don’t panic!

There are many common problems that can be easily fixed with some troubleshooting.

In this guide, we’ll provide expert tips and solutions for troubleshooting water heaters, so you can get your hot water flowing again.

Whether you’re experiencing no hot water, strange noises, or leaks, we’ve got you covered with DIY solutions that can save you money and ensure your water heater is operating at its best. Let’s get started!

Plumbing tools to repair water heaters
photo: pixabay

Troubleshooting Water Heaters: Common Problems, Causes, And Symptoms

Troubleshooting water heaters involves identifying the most common problems, their causes, and symptoms. To help you get started, here is a list of the most frequent issues you may encounter with your water heater. Understanding these problems can help you diagnose and fix the issue quickly and effectively.

This water heater troubleshooting guide contains a lot of information and can be used to repair most electric and gas-powered units sold in the US and Canada, including brands like Rheem, AO Smith, Bradford White, American, State, and others.

Keep in mind that symptoms of water heater failure are very similar among different manufacturers, and directions for one model can often be applied to others.

To better understand propanenatural gas, and electric heaters, we recommend that you become familiar with articles on how these units work and their main parts. Once you have all the necessary information, troubleshooting water heaters becomes much easier.

Water heater problems are not complicated to diagnose, and if you’re familiar with DIY home and plumbing projects, have the necessary tools, skills, and the right guide, you can successfully repair a water heater without calling a plumber.

Note: Any issues with plumbing, gas, and electricity should be performed by a qualified plumber or HVAC technician.

Water Heater Troubleshooting Tips

To make this guide easier to understand and help you fix your heater like a pro, we have provided a lot of information about common problems, their causes, and symptoms of water heating issues. Some of this information can be found in this article, while other details are covered in our articles about gas water heater problemsrepairing electric type, or tankless. Be sure to check them out!

How To Fix Leaking

leaky water heater is the most frequently reported problem by many people and is often found in consumer reports. The reason for this malfunction might be that the tank’s steel body has corroded to the point of causing a rupture in the tank, resulting in a water leak.

Another reason for a leak is the water discharge from the temperature and pressure relief valve (TPR) due to overheating.

If you see a puddle of water on the floor your water heater might be leaking from the top or bottom connections.

How To Prevent or Repair Water Heater Condensation

So, you have found a small puddle of water under your water heater and are wondering whether the heater is leaking or if the issue is with condensation. For proper troubleshooting, keep in mind that condensation is often present on newer models, such as condensing units, as these units are more efficient than older ones.

A typical water heater will produce approximately one-half gallon of water vapor during every hour of operation. Condensation usually occurs shortly after the heater starts. Follow the provided link to learn more about what causes condensation, how to prevent and deal with it.

Dripping Valves And Fixtures

A puddle of water under a tank-type water heater is often related to water leaking and condensation. However, if you notice dripping from the relief valve or a fixture during the unit’s recovery cycle and when no hot or cold water is being used, there might be another issue at play.

Find out what causes dripping and how to fix it.

Thermostat Problems

If the water is too hot or cold, you might have a problem with a faulty thermostat. Use this article to learn how to troubleshoot and replace a thermostat, ensuring a comfortable shower once again.

Sediment Build-Up

Check out this repair guide to fix strange noises in your water heater and improve its overall performance. The main problem is usually sediment build-up at the bottom of the tank, which must be addressed correctly and promptly.

You can also learn how to reduce the effects of hard water by using a water softener.

Discolored Water

If your hot water has a milky or rusty appearance, or is discolored, the anode rod could be one of the culprits. Learn how to fix the problem and what might be causing it.


Discover the causes of corrosion and learn effective prevention techniques to ensure that rust doesn’t contaminate your hot water or weaken your heating system’s structure.

By learning about the reasons for this problem, you can take preventative measures and extend the lifespan of your water heater.

How To Repair A Water Heater And Eliminate Rotten Egg Odor

Sulfur or rotten egg odor in your water is often caused by bacteria that thrive on the decomposing sacrificial anode inside the tank. Learn how to eliminate bacteria from the system with the chlorination procedure. If your water heater does not have an anode or has powered rods, you won’t have this issue.

Find out how to fix smelly water and improve the quality of your hot water.

Water Hammer And What You Can Do About It

Water hammer, which refers to the loud and destructive hydraulic shock that occurs in the house plumbing system and water heater, is a common problem that can be easily fixed. Understanding the causes and solutions of water hammer is important to prevent any potential damage to your plumbing and heating system.

Heat Traps Issues

Heat traps are installed in water heaters to improve their energy efficiency, but they can also be the source of various sound problems, such as ticking, clicking, humming, or tapping. If you suspect that the heat traps are the source of these issues, this guide can help you remove or reinstall them.

Fixing A Noise Problem

Water heater noise can be caused by two main conditions: water hammer and mineral build-up, and the most common sounds you can hear are pounding, rumbling, crackling, popping, ticking, and sizzling.

Pilot Light Problem

Pilot outage, or when the pilot light goes out, is a common issue with gas-fired water heaters. Improper venting is one of the primary causes of this problem, so it’s important to know how to prevent and fix it.

These articles will show you how to light a burner properly and what to do if you see a flashing green light on your gas control valve.

If you’re unable to fix the issue yourself, it may be necessary to contact a professional to help with your pilot light issues.

Cold Water Sandwich

If you’re experiencing fluctuating water temperature that go from hot to cold and vice versa, this guide can help you fix the issue and enjoy a comfortable shower with less of the “cold water sandwich” effect.

Storage Tank Bulging Problem

Excessive pressure on a water heater can cause cockeyed nipples at the top and a bulged or reversed bottom of the head. This guide explains how to fix the bulging problem and prevent it from happening again.

If your water heater cannot be repaired, learn how to properly dispose of it.

Burner Flame Issues

Improper gas combustion can be dangerous. Signs include a yellow, orange, red or lazy burner flame, slow hot water recovery, failure to ignite, combustion odor, smoking and sooting, or a floating burner flame.

If you notice any of these signs, read our article on “how to properly vent a gas water heater” to learn how to fix the issue. Additionally, it’s important to check for carbon monoxide emission, which can cause gas poisoning and even more dangerous situations.

Slow Hot Water Delivery

Are you tired of waiting too long for hot water at the kitchen sink or in the bathroom? Discover the possible causes behind slow hot water delivery and explore solutions to get hot water faster.

Plumbing Crossover

A common reason for complaints about not enough hot water or hot water running out quickly is plumbing crossover. Learn how to prevent, test, and successfully repair it with this guide.

Winterizing Tankless

If your tankless water heater is malfunctioning due to freezing temperatures, check out this article to learn how proper winterizing can help you avoid this issue in the future.

Proper Diagnosis Is Crucial For The Successful Water Heater Repair

When troubleshooting an electric or gas hot water heater, it’s important to recognize the symptoms of a problem before it becomes a big issue. These symptoms can include low performance, uncomfortable temperature, reduced efficiency, insufficient hot water, or no hot water at all. Once you’ve identified the problem, it’s important to troubleshoot and fix it promptly.

Electric models are generally easy to troubleshoot, while gas heaters can be more complicated. However, with basic knowledge of the heating process and the unit’s anatomy, repairs can often be made.

Tankless models are even more complex, but many models come equipped with diagnostics systems that make troubleshooting easier.

Proper problem diagnosis can save you time and money, as many water heating problems have simple solutions such as adjusting temperature settings or replacing a blown fuse at the breaker. Regular maintenance and servicing of the unit is also important for preventing problems and extending the life of the heater.

YouTube Video 1: Troubleshooting Gas Water Heaters

YouTube Video 2: More Tips About Troubleshooting

Preparing A Site For The Water Heater Repair

When it comes to repairing your water heater, proper preparation is crucial to ensure a smooth and successful repair process. Here are some tips to help you prepare your site for water heater repair:

  • Turn off both gas and electric power before working on the heater: Safety should always be a top priority when working with water heaters. Turning off both the gas and electric power to the unit is essential to avoid any potential accidents or hazards.
  • Shut off the water supply to the heater: It’s important to shut off the water supply to the heater before beginning any repair work. This will prevent any additional water from flowing into the tank while it’s being worked on, which could cause flooding or other water-related damage.
  • Plug the garden hose into the drain valve: In order to drain the tank and perform repairs, a garden hose will need to be attached to the drain valve. Be sure to have a bucket or other receptacle ready to catch the water as it drains out.
  • Prepare the necessary tools: Before beginning any repair work, make sure you have all the necessary tools on hand. This can include things like wrenches, screwdrivers, pliers, and other hand tools, as well as replacement parts like heating elements, thermostats, and more.
  • Clear the area around the water heater: Make sure to clear the area around the water heater to provide enough space to work comfortably. Move any furniture, boxes, or other items out of the way to create a clear workspace.


Overall, troubleshooting water heaters requires a combination of knowledge, skills, and attention to detail. Being proactive about maintenance and repair can save you a lot of trouble in the long run, and it’s important to remember that prevention is always the best course of action. By staying informed about your water heater’s condition and taking steps to address any issues that arise, you can ensure that it continues to provide hot water efficiently and reliably for years to come.

So, whether you’re dealing with a minor problem or a more complex issue, don’t hesitate to seek out resources and support to help you troubleshoot and fix the problem. With the right tools and techniques, you can keep your water heater in top shape and avoid costly replacements or repairs.

For additional help, use the AO Smith website with the links to the service handbooks (in pdf format).

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