Troubleshooting Water Heaters: Common Problems and a Repair Guide

If you’re having issues when troubleshooting water heaters, don’t worry—help is here! You can easily fix many common problems with the right tips and tools.

In this guide, we’ll walk you through the most common issues and provide easy-to-follow solutions to get your hot water running smoothly again. Whether it’s strange noises, no hot water, or leaks, you’ll find practical DIY fixes that can save you time and money.

Let’s dive in!

Prioritizing Safety in Water Heater Troubleshooting

While troubleshooting water heaters may seem daunting, safety should always be your top priority. Whenever possible, seek the assistance of a qualified professional to avoid unnecessary risks.

Key Safety Precautions

1. Turn Off Power
   For electric water heaters, the first step is to turn off the power at the circuit breaker or fuse box. Use a multimeter to confirm that the heating elements are not energized before working on the unit.
2. Gas Water Heaters
   • Turn off the pilot light and close the main gas valve.
   • If you smell gas, do not turn on any electrical switches or appliances, as even a small spark can be hazardous.
   • Immediately leave the area and call a plumber or your gas supplier from a safe location, such as outside your home.
3. Exhaust Gas and Carbon Monoxide
   • Ensure the venting system is intact and free of obstructions. Damaged or improperly installed vents can cause exhaust gas leaks, releasing dangerous fumes into your home.
   • Carbon monoxide (CO) is a colorless, odorless, and potentially deadly gas produced by incomplete combustion in gas water heaters. Install a carbon monoxide detector near the unit and check it regularly.
   • If you suspect a carbon monoxide leak or experience symptoms such as dizziness, headaches, or nausea, evacuate immediately and contact emergency services.

Understanding Gas Leaks

If you detect a gas smell, remember:

• Natural gas: Naturally odorless, but an added scent helps identify leaks.
• Propane or LP gas: Heavier than air and tends to accumulate in lower areas. Always check for gas leaks near the floor before igniting a gas water heater.

To ensure safety, inspect gas fittings and connections using a soapy solution to detect leaks. Bubbles indicate a leak that must be addressed by a professional.

Also it is important to familiarize yourself with how a gas and electric units work including the main function of their primary components. Once you understand these, troubleshooting water heaters will become more manageable, and repairs will be quicker and less expensive.

A Guide to Troubleshooting Water Heater: Common Problems, Causes, and Solutions

Troubleshooting water heaters involves identifying the most common problems, their causes, and symptoms.

Keep in mind that symptoms of water heater failure often appear similar across different manufacturers. You can usually apply instructions for one model to others.

Diagnosing these issues is typically straightforward. If you’re experienced with DIY home and plumbing projects, have the right plumbing tools, and follow a reliable guide, you can repair a water heater successfully without calling a plumber.

To help you get started, here’s a list of the most common issues (with links) you may encounter with your heating device. Understanding these problems will help you diagnose and fix the issue quickly and effectively.

No Hot Water from a Gas Heater

If your gas water heater isn’t producing hot water, start by checking the gas supply and the components inside the combustion chamber. These are common areas where issues can arise and may need attention.

• Gas Valve: Ensure the valve is functioning properly to avoid further complications.
• Gas Supply: Make sure gas is flowing to your home and the heater. Obstructions, shortages, or a closed valve could be the issue.
• Pilot Light: If the pilot light is out, relight it according to the manufacturer’s instructions. If it won’t stay lit, you might need to replace the thermocouple.
• Lukewarm Water: This could signal sediment build-up in the tank, which reduces heat transfer. Flushing the tank may help restore performance.

No Hot Water from an Electric Heater

If an electric water heater isn’t producing hot water, the issue could stem from a lack of power or a faulty component. Here’s how to troubleshoot:

• Power Supply: Check the breaker, reset button, and heating elements for proper operation.
• Component Failure: Burned-out elements, faulty thermostats, or a broken dip tube can cause sudden interruptions in hot water.
• Tank Capacity: If you’re using more hot water than the tank can handle, give it time to recover.
• Thermostat Settings: Make sure the thermostat is set between 120–125°F and is free of limescale for accurate temperature control.

Water Too Hot from a Gas Water Heater

If your gas water heater is producing scalding water, the problem may lie with the thermostat or gas control valve. Here’s what to do:

• Thermostat Settings: Set the thermostat to a safe range of 120–125°F to prevent burns, especially in homes with children.
• Calibration: Ensure the thermostat is securely attached and properly calibrated.
• Gas Burner: Overheating may result from an improperly adjusted burner.
• Mixing Valve: Consider installing a mixing valve for consistent and safe water temperatures.

Water Too Hot from an Electric Water Heater

When your electric water heater overheats, it’s often due to a faulty thermostat or heating element. Here’s how to fix it:

• Thermostat: Verify that the thermostat is correctly set and flush against the tank for accurate readings.
• Heating Element: Inspect for grounding issues that may cause uncontrolled heating.
• Mixing Valve: Install a mixing valve to regulate hot water temperature and enhance safety.

How to Fix Leaking

A leaking water heater is a common problem that requires prompt attention to avoid water damage. Here’s what to look for:

• Corrosion: Over time, the tank’s steel body may corrode, leading to cracks and leaks.
• TPR Valve Discharge: If the temperature and pressure relief (TPR) valve releases water, overheating might be the cause.
• Puddle on the Floor: If your water heater is leaking from the top or bottom, inspect all connections carefully to identify the source of the leak.

How To Prevent or Repair Water Heater Condensation

So, you have found a small puddle of water under your heater and are wondering whether the heater is leaking or if the issue is with condensation. For proper water heater 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

If you spot a puddle under your heater, it could be due to condensation or a leak. However, if the relief valve or a fixture drips during the recovery cycle when no water is being used, there may be a more serious issue.

Find out what’s causing the dripping and how to fix it.

Thermostat Problems

Is your water too hot or too cold? A faulty thermostat might be to blame. Knowing how to troubleshoot and replace a thermostat can restore your comfort and make your showers enjoyable again.

Learn how to fix thermostat issues and take control of your water temperature.

Sediment Build-Up

Strange noises from your water heater or declining performance are often signs of sediment build-up at the bottom of the tank. Left unaddressed, this can cause significant damage.

Discover how to remove sediments and reduce hard water effects with a water softener.

Discolored Water

If your hot water appears milky, rusty, or discolored, a decomposing anode rod could be the problem. Addressing this issue quickly can improve water quality and prevent further damage.

Learn how to fix discolored water and understand what’s causing it.

Corrosion

Rust can weaken your heater’s structure and contaminate your water. Knowing how to prevent and address corrosion can extend your unit’s lifespan.

Find out how to prevent and stop corrosion and keep your device in top shape.

How to Repair a Water Heater and Eliminate Rotten Egg Odor

Does your hot water smell like sulfur or rotten eggs? This odor is usually caused by bacteria feeding on the anode rod inside the tank. A chlorination procedure can eliminate the bacteria and solve the problem.

Discover how to fix smelly water and improve its quality today.

Water Hammer and What You Can Do About It

Loud banging or knocking sounds in your plumbing? That’s water hammer, a hydraulic shock that can damage your plumbing and water heater. Addressing it early is key to avoiding costly repairs.

Learn how to prevent water hammer and protect your system.

Heat Traps Issues

Heat traps improve energy efficiency but can sometimes cause annoying sounds like ticking, clicking, humming, or tapping. If you suspect heat traps are the culprit, you can easily remove or reinstall them to resolve the noise problem.

Learn how to fix heat trap issues and enjoy a quieter water heater.

Fixing a Noise Problem

Noises like pounding, rumbling, crackling, popping, or sizzling can stem from water hammer or mineral build-up in the tank. Addressing these issues promptly will prevent further damage and restore quiet operation.

Find out how to silence your noisy water heater.

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 (Gas Models)

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.

Troubleshooting 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.

Lack of Oxygen (Gas Models)

Gas water heaters require a steady supply of fresh air for combustion. If airflow is restricted, you might notice symptoms like a yellow flame, pilot outages, sooting, or even carbon monoxide presence.

If there is insufficient air flow, problem symptoms are seen as follows:

• Pilot outage
• Yellow burner flame
• Sooting burner flame
• The smell of burnt gas in the room
• The possible presence of carbon monoxide.

The solution is prevention; check and provide enough airflow; check the flue vent and base of the water heater for possible obstructions, and do not cover it with the insulation blanket. Clean the flame arrestor regularly.

Sooting (Gas Models)

Soot build-up in the gas chamber or flue vents can signal airflow issues, incorrect orifices, or excessive gas pressure. Regular maintenance and following manufacturer specifications are key to resolving this problem.

Learn how to repair sooting issues and keep your gas water heater running safely.

Burner Won’t Stay Lit (Gas Models)

The gas burner won’t stay lit due to the following reasons:

• High ambient room temperature
• Dirty or clogged air intake
• Obstructions in the vent
• Blocked Flame arrestor openings

This article will guide you on how to repair a gas water heater with a gas burner that is not working.

Pilot Light Won’t Light or Stay Lit (Gas Models)

If your pilot light won’t light or keeps going out, start by checking the gas supply to ensure it’s adequate and that the pressure is correct. If the gas supply is compromised, contact your utility provider, and if air has entered the gas line, have a certified technician bleed it. When lighting the pilot, press and hold the button fully, and confirm the pilot electrode sparks and the piezo igniter works. Clean any clogged pilot tubes or orifices, and replace faulty components like a defective magnet or thermostat-gas valve.

If the problem persists, tighten a loose thermocouple connection, reposition it to make solid contact with the pilot flame, or replace it if damaged. Inspect the vent system for blockages or improper installation, as well as airflow issues that could snuff out the flame. For Honeywell gas valves, refer to flashing green lights for error codes. Proper maintenance and troubleshooting will help ensure your gas water heater operates safely and efficiently.

The Breaker Is Tripping

If your breaker trips frequently, start by inspecting the electrical wires for short circuits. Check whether the heating element or thermostat is grounded and verify if the breaker is the correct size for your model.

Find out how to fix breaker issues and maintain a reliable electric water heater.

Heating Elements are Burned Out

Heating elements can burn out if they’re not fully submerged in water, especially in models without dry-fired heating elements. This can occur when the tank isn’t completely full, even if part of the element is exposed to air. Signs of failure include a soft shaft, holes burned through the surface, or visible melting.

In addition to dry-firing, heating elements often fail due to limescale build-up, voltage spikes, or lightning strikes.

Learn how to identify, troubleshoot, and replace burned-out heating elements to keep your water heater working efficiently.

Related: Hybrid water heater repair tips

Proper Diagnosis is Crucial for Successful Troubleshooting Water Heaters and Repair

When troubleshooting water heaters, 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 Water Heaters

Preparing a Site for the Water Heater Repair

When troubleshooting water heaters, note that proper preparation is crucial to ensure a smooth and successful repair process. Here are some tips to help you prepare your site for the 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.

Conclusion

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).