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 usefull repairing tips.

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!

Troubleshooting a Water Heater: Prioritizing Safety

While troubleshooting a water heater 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 water heater’s 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 water heater 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 will become more manageable, and repairs will be quicker and less expensive.

Water Heater Troubleshooting: Identifying Common Issues, 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 are often similar across different manufacturers, and instructions for one model can often be applied to others.

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

To help you get started, here is a list of the most frequent issues (including links) you may encounter with your water heater. Understanding these problems can help you diagnose and fix the issue quickly and effectively.

No Hot Water from a Gas Water Heater

If repairing a gas water heater, first ensure gas is being supplied to your home and unit, as obstructions, shortages, or a closed main valve could be the issue.

If hot water turns cold, you might be exceeding tank capacity—wait for recovery. A no hot water problem could also mean the pilot light is out; follow the unit’s instructions to relight it. If it won’t relight, the thermocouple may need replacing.

Lukewarm water may indicate sediment build-up, disrupting heat transfer.

Finally, check if the gas valve is functioning properly.

No Hot Water from an Electric Water Heater

To troubleshoot an electric water heater with no hot water, start by checking the power supply, reset button, and voltage at the heating elements.

Issues like tripped breakers, faulty thermostats, or burned-out heating elements may need attention.

Sudden hot water interruptions could be due to exceeding tank capacity, sediment build-up, or broken components like the dip tube.

Common problems include improper wiring, circuit overload, high/low voltage, or loose connections, all of which can damage the thermostat or elements.

Ensure the thermostat is set correctly (120–125°F) and free of limescale.

Address leaks and undersized tanks for optimal performance.

Water Too Hot from a Gas Water Heater

If your gas water heater produces excessively hot water, it could indicate a faulty thermostat or a malfunctioning gas control valve. Ensure the thermostat is set to a safe temperature, typically between 120–125°F, to prevent scalding, especially if children are present. Verify that the thermostat is properly calibrated and securely attached to the tank.

Overheating may also occur if the gas burner is improperly adjusted. As a precaution, consider installing a mixing valve to regulate the outgoing hot water temperature for safety and consistency.

Water Too Hot from an Electric Water Heater

For electric water heaters, excessively hot water is often caused by a misconfigured or malfunctioning thermostat. Check that the thermostat is set to a safe temperature and is installed flush against the tank to accurately sense the water temperature.

If overheating persists, inspect the heating element for grounding issues, which can cause uncontrolled heating.

Installing a mixing valve can provide additional safety by maintaining a consistent and safe hot water temperature. Immediate action is critical to prevent burns and ensure the system operates safely.

How to Fix Leaking

A 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.

Corrosion

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.

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.

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)

For the proper operation of gas water heaters, fresh air needs to be delivered for complete gas combustion. The air should enter the gas chamber from the base of the unit and enter the flue vent from below the draft hood.

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)

To effectively repair a gas water heater that is experiencing sooting issues, it’s important to check for potential airflow problems if the device is running and the gas chamber and flue vents are sooted, even if the burner appears to be clean.

If all of these components are sooted, then it may be due to a wrong orifice being used, excessive gas pressure, or loose gas connections in the burner assembly.

If the pilot flame or the main burner flames are too large or small, there might be some dirt and debris in the orifice or gas supply tubing, or an incorrect orifice size has been used. Follow the manufacturer’s manual for the right specs.

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
• Flame arrestor openings are blocked

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)

Start by checking the gas supply to confirm there’s enough gas and that the pressure is adequate. If you notice any issues with the supply, contact your utility company right away. If air has entered the gas line, a certified technician should bleed it to restore proper flow.

When lighting the pilot, press and hold the pilot light button completely. Check if the pilot electrode is sparking correctly and ensure the piezo igniter works as it should. Replace any faulty parts, such as a defective magnet or thermostat-gas valve. If the pilot tube or orifice is clogged, clean it thoroughly to allow proper gas flow.

If the thermocouple connection feels loose, tighten it by hand and then secure it with a 1/4 turn using a wrench. Position the thermocouple so it makes solid contact with the pilot flame, and replace it if it’s damaged. Examine the igniter wire for melted insulation or shorting, and install a new one if necessary.

If the pilot light keeps going out, identify and address potential causes. Condensation might be snuffing out the flame, there could be insufficient air for combustion, or the vent system might be clogged or improperly installed. An inconsistent gas supply or low pressure can also cause the pilot to go out.

For water heaters with a Honeywell gas valve, watch for a flashing green light. These lights indicate specific error codes, so refer to the manual for troubleshooting steps to fix the issue.

Pilot outages, or when the pilot light goes out often occur due to improper venting, which is one of the most common problems with gas-fired water heaters. Make sure the venting system is installed and maintained correctly to avoid this. To learn more, check out guides on properly lighting a burner and troubleshooting flashing green lights on gas control valves.

Corrosion

Professional gas water heater repair can be necessary if the unit is exposed to contaminated atmospheres in residential or commercial applications, which can cause corrosion.

This often happens when the gas unit is installed near an air supply that contains chemicals and corrosive elements such as chlorine, fluorine, industrial glue, acids, sodium, calcium chloride, cleaning solvents, aerosol with Freon, etc. The air might be ok to breathe, but when exposed to high flame or hot air temperatures, corrosive elements are released, affecting the proper operation.

Common problems include tank and vent corrosion, flue tube collapsing, and heavy scaling on the elements.

The solution to this problem is to avoid installing a water heater near beauty shops and areas exposed to swimming pool chemicals, bleaches, gasoline, etc. If you cannot isolate the unit from the corrosive atmosphere, try to bring the uncontaminated air in for proper combustion.

The Breaker is Tripping

Check the electric wires; they might be shorted. Check if the heating element and thermostat are grounded. Is the breaker correct size? Find out what to do if the heater keeps tripping the breaker.

Heating Elements are Burned Out

Unless the water heater is equipped with the dry-fired heating elements, the standard type can easily and instantly burn out if it is not fully submerged into the water (the tank is not full of water), even if the element is partially exposed to the air.

In such case, the element shaft becomes so soft that it can be bent by hand, a hole is burned through the surface, or there are signs of melting.

Except the mentioned dry-firing, water heater elements can fail, some sooner some later, due to; limescale build-up, voltage spikes or lighting. Find out more about element failures and solution here.

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.

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).