How to Pinpoint and Fix Your Hot Water Heater Problems

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Unless you’re into cold showers, the sudden failure of your water heater is likely quite a shock. Looking at the ticket price for a new one, or the repair bill on the old, will undoubtedly give you another shock to top it off. Save your heart – and your pocketbook – by troubleshooting your water heater problem yourself.

How Your Water Heater Works

At the simplest level, your water heater transfers heat to a water source, which then is routed through your plumbing to the site of demand. The picture in your mind is probably the classic tall, cylindrical tank, full of water standing at the ready, typically heated by either natural gas or electricity. Advanced water-heating systems emerging in the American consumer market are gradually replacing the traditional tank-based electric and gas water heaters, however.

At the simplest level, your water heater transfers heat to a water source, which then is routed through your plumbing to the site of demand.

Electric heat pump water heaters use energy from the air to heat the water while dehumidifying the air at the same time – a bonus in basements or humid climates. Gas-fueled or electric tankless or demand-type water heater systems heat the water as it flows through the pipes, by means of a heating element, eliminating the need for a traditional tank. The new tankless systems not only last longer than conventional gas and electric hot water heaters, they are much more energy efficient as well.

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Until the initial cost of newer water-heating systems drops, standard tank-based gas and electric water heaters will likely continue to occupy most homes. Both operate on the same principles and troubleshooting for both is much the same.

The cold water supply pipe delivers fresh water to your water heater and a dip tube routes it to the bottom of the typically steel tank. When you take your hot shower, the heated water, stored in the tank, flows from the top of the tank and out the hot-water pipe.

Steel water tanks are insulated on the exterior and have a glass-lined interior to prevent corrosion, which is the leading cause of tank failure. Rust will quickly eat through exposed metal, requiring total replacement of the tank itself. An anode rod, made of magnesium, runs down the middle of the water tank in an effort to attract the rust to it instead of the steel. Designed to corrode away, it does, leading to eventual tank failure if not checked annually and replaced as necessary.

Outside of the tank, your water heater has a temperature-and-pressure relief valve, or T&P valve. The T&P valve is located on a pipe that runs from the top of the water heater to about 6 inches above the floor before abruptly ending. The T&P valve is designed to open if either the pressure or the temperature inside your water heater exceeds defined limits. Keep a bucket underneath the T&P pipe to catch draining water if the valve opens.

Every water heater tank also has a drain cock at the bottom of the tank, which allows you to drain water, as well as a water-supply valve on the incoming cold-water supply pipe.

The new tankless systems not only last longer than conventional gas and electric hot water heaters, they are much more energy efficient as well.

Electric water heaters are generally wired to a 220-volt circuit breaker. An attached thermostat senses the water temperature inside the tank. When your hot shower runs, the temperature drops, and the thermostat closes the electrical current that allows the electricity to flow into the unit. Inside, heating elements conduct the electrical current that heats the water. Once the water temperature again reaches the proper temperature – typically 120, 130 or 140 degrees Fahrenheit, the thermostat closes to break the circuit and thus ends the water heating.

Gas water heaters, in contrast, use a gas burner underneath the tank to heat the water. The fuel is piped from the source to the gas control valve. A thermostat detects the water temperature and opens or closes the fuel delivery to the burner. A thermocoupler – essentially a safety device – ensures the pilot light or spark ignition activates properly before allowing the burners fuel. Gasses produced during combustion flow through and out the top of the tank, into a vent pipe and typically out the roof or sidewall.

As with an electric hot water heater, a gas water heater has the same anode rod inside the tank. The longer the anode, on either gas or electric water heaters, the longer the tank will last. However, since the burner heats the tank itself, the gas-fueled water heater tank experiences greater wear and tear and thus a shorter life expectancy.

The incoming cold water pipe should have a shut-off valve, and a drain valve will be at the bottom of the tank exterior, just like on an electric water heater. The T&P valve operates exactly as it does on an electric water heater.

Common Water Heater Problems and Causes

From minor inconveniences such as discolored water or water that seems just a little too cool, to a major crisis like ice-cold water in your shower or water pouring out the water heater tank, the problems you may experience with your gas or electric water heater are easier to understand with knowledge of how the hot water actually works. In addition, many of the problems you may experience are common to both electric and gas water heaters. Search for the possible cause and solution by the symptom. For more advanced troubleshooting and repairs, consult a qualified appliance repair technician.

The problems you may experience with your gas or electric water heater are easier to understand with knowledge of how the hot water actually works.

Hot Water is Discolored

Dirty brown or rust-colored hot water usually indicates a build up of rust and sediment inside your hot water heater. Excessive sediments may also make the water take longer to heat and cause popping noises during the heating cycle. The solution is simple – drain the water and flush before refilling.

Hot Water Smells

If your water smells like rotten eggs, it indicates an excess of hydrogen, sulfur and bacteria. This is especially prevalent in homes with well water. The magnesium anode rod inside your tank emits hydrogen, while the water supplies the sulfur and bacteria. Treat the problem with two solutions: First, replace your old anode with a new aluminum one, which will lower the hydrogen content. Next, chlorinate your water supply to kill the bacteria. Flushing the tank and rinsing it with chlorine bleach before replacing the anode will help the problem tremendously. Consult a water heater professional for further information.

Water Heater is Noisy

Rumbling, rattling and popping noises may be quite normal, although they may startle you, especially in a new home where you aren’t used to the sounds your appliances make. Sure, rumbling may be a sign of sediment and a popping noise may indicate T&P valve stress, but don’t borrow trouble – if everything works properly or if the noise is nothing new, there’s likely nothing to worry about. Keep an eye on how your water heater performs to determine if the sound is, indeed, a symptom of another problem.

Hot Water Pressure is Low

When you notice your hot water doesn’t flow as hard as it should, you need to check several possible causes, from the faucet back to the water heater. At any point that the troubleshooting proves too difficult for you to perform, have a qualified professional take over. As with all do-it-yourself troubleshooting, chances are good that the repair bill will still be much lower, even if you can’t find or fix the problem, since you have narrowed down the possible causes. One by one, check the following parts and proceed as necessary:

  1. Is the water shut-off valve at the water heater partially closed?
  2. Unscrew the faucet aerator, the round tip under the faucet that sprays the water flowing from the tap. Is it clogged with gook or sediment? Soaking the aerator in a bowl of vinegar overnight, then scrubbing with an old toothbrush, should solve this problem.
  3. Is the faucet water shut-off valve completely open?
  4. Remove and check the faucet supply line pipe. A clogged pipe will restrict water flow as well. Clean or replace as needed.
  5. Check the hot water line, leaving the hot water heater, for sediment and debris. Call a professional for assistance with this and internal water heater repairs if you lack the experience and confidence to do it yourself.
  6. If the water heater’s dip tube, inside the tank, is clogged, it will also slow the hot water flow, presenting as low water pressure. The dip tube has small drain holes at the bottom that may easily fill with sediment or plumbing sealant and other debris that enters the system. Sometimes the dip tube may even break with age. Replacing the dip tube is simple, but you may wish to have a service technician perform the work for you.

T&P Relief Valve is Leaking Water

The first thing to assess is just how much water is leaking. A dribble typically points to a totally different set of possible causes than a rush of water from the T&P. For slight leakage, the cause is generally minor and the fix simple:

  • A loose or malfunctioning T&P will show as a slight trickle or small accumulation of water. To replace the valve, the tank is first drained before a new T&P is added in place of the old one.
  • A flood of water likely indicates that the temperature or pressure inside the tank is too high and the T&P is working as designed. While that’s good news for your water heater and personal safety (the tank will not blow, spewing scalding water), it’s bad news for your floor as gallons of water flood it. Often, it’s the result of a malfunctioning thermostat that allowed the water temperature to rise too high. Consult a qualified professional who has the ability to troubleshoot the water heater thoroughly and safely and guide you to the appropriate solution.

Water Drain Valve is Leaking

Parts may wear out simply due to age. If the drain cock is dribbling water, draining the tank and replacing it before refilling it with water should fix the problem.

Water Heater is Leaking From Unknown Source

If you find wetness around your water heater but aren’t sure where it’s coming from, you need to investigate further. Other than the valves – which you already have eliminated as a possible cause – the water heater may leak from either the pipe leading into the tank or the pipe leading away from it. If you look at and feel these pipes and they are dry, suspect a leaking tank. Most water heaters last 10 to 15 years before failing. Even a slight pinhole in the tank will cause failure. While pipes, valves and many components may be replaced, there is no way to patch a tank. A leaking tank requires total replacement.

Takes Too Long to Get Hot Water From Faucet

Because your hot water supply pipe, emerging from the water heater, constantly contains water, it will cool slightly when you’re not running your hot water faucet. The cooler the temperature surrounding the pipes, the more the water cools. To get fresh, hot water, you must run enough to clear the standing water first. Pipe insulation will help slightly, but the delay is completely normal.

Water Heater Runs Out of Hot Water

Sometimes your water heater is simply too small to handle the demand placed on it. The result is running out of hot water. Other possible causes, common to both electric and gas water heaters, include improper installation of a new water heater, leaks in the hot water line resulting in less hot water making it to the faucet, or excessive sediment in the tank, especially in areas with hard water. Dirty-colored water, a noisy water heater and low water pressure in combination with a lack of hot water are tip-offs that sediment is the problem. While flushing the tank of sediment is a do-it-yourself project for many, consider consulting a service technician for professional assistance with any of these causes.

water heater troubleshooting

Troubleshooting an Electric Hot Water Heater

Some problems you may experience with your water heater may occur in both gas and electric models, but the precise causes will vary due to the difference in how electric and gas water heaters work. Still, the troubleshooting process remains the same – search by symptom and narrow down the possible causes. Consult a qualified service technician for further information or advanced repair assistance.

If you’re not getting any hot water at all, start with the simplest possible causes first. Make sure the water heater is turned on and that the breaker isn’t flipped.

Runs Out of Hot Water

If you still run out of hot water and have performed the general troubleshooting, looking for sediment and other common causes, then the problem is likely due to parts specific to an electrical water heater. Among the most common are defective heating elements, faulty or improperly wired thermostats and loose wiring. If the tank is not grounded properly, you may also have hot water supply issues. A qualified service professional has the knowledge and tools to narrow down the cause and repair, as well as to replace or rewire as needed.

Takes Too Long to Get Hot Water

After checking the common causes applicable to both gas and electric water heaters, turn your attention to the electrical heating system itself. If the heating elements are too small or the thermostat malfunctions, the water may be not hot enough and sluggish as well.

Water is Too Hot

The first thing to check, on both gas and electric water heaters, is that your water temperature setting control is at the temperature you desire. For most households, 120 degrees Fahrenheit is adequate and safeguards against accidental scalding. If the setting is appropriate, hold a thermometer under steady running hot water to check the temperature of water delivered. Excessively high water temperature is typically caused by a faulty thermostat or a grounded heating element, meaning the heating element touches the inside of the tank when it shouldn’t. Consult a repair technician for further information and assistance.

Electric Water Heater Isn’t Working

If you’re not getting any hot water at all, start with the simplest possible causes first. Make sure the water heater is turned on and that the breaker isn’t flipped or the fuse blown in your home’s fuse or breaker box. If you have a breaker box – most modern homes do – flip the switch completely off and back on again even if the breaker wasn’t thrown. This resets the electronics inside the water heater. Other possible causes include a grounded or out-of-calibration thermostat and loose or faulty wiring as well as a tripped high limit switch. Contact a qualified service technician for in-depth troubleshooting and assistance.

Troubleshooting a Gas Hot Water Heater

After troubleshooting general symptoms and causes for your gas water heater problems, turn to troubleshooting geared specifically to a gas water heater. Although many of the parts that make a gas water heater work are mechanical instead of electric, making some repairs easier, there are more parts. Burners, ignition systems, gas valves and such may all malfunction. As with an electric water heater, consult a qualified repair technician to assist with advanced troubleshooting and repairs you are not comfortable attempting.

Inspect your hot water heater completely at least once a year. Performing the inspection during your routine fall or winter maintenance will help you remember to do it.

Runs Out of Hot Water Quickly or Reheats Water Slowly

If you have eliminated generic problems such as improper temperature settings, a defective dip tube or an undersized water heater, the problem is often either a defective water temperature thermostat – requiring replacement of the gas control valve – or the burner orifice is dirty and clogged, fixable with a simple cleaning. Other possible causes include low gas pressure, an excessively dirty vent flue or a downdraft through your flue. Downdrafts – air coming down your flue pipe – may be periodic and require you to simply relight your pilot light for normal operation to continue. If the downdraft continues, or if you suspect an obstruction in the flue from things such as leaves, bird’s nests or excessive soot, inspect the flue from the point it exits the house. The end of the pipe may need to be raised to prevent a downdraft, the flue may need to be cleaned and the cap covering it may be loose. Consider cleaning the flue yourself, if necessary, or consult a professional for expert assistance.

Water is Too Hot

After checking your temperature control setting to ensure it wasn’t accidentally raised, suspect a thermostat problem. Replacing the thermostat is fairly inexpensive and takes only a few minutes for a professional.

No Hot Water

Always check your fuse or breaker box to ensure the power is on to the water heater. Although it’s gas-powered, an electronic ignition requires a small amount of current. Check the pilot light to see if it is lit and relight if necessary. If it fails to stay lit, troubleshoot the pilot light failure as well.

Pilot Light Won’t Light

If the gas control knob is open, allowing an adequate gas supply to the pilot and burner, then the pilot light orifice or tube may need to be cleaned or replaced. A loose or defective thermocoupler will also prevent your pilot light from lighting. Air in the gas line may prevent lighting as well. Even a defective gas valve will prevent proper pilot light operation. Consult a service technician for further information or assistance.

Pilot Light Won’t Stay Lit

Just as frustrating is a pilot light that simply won’t stay lit. Sure, you may be able to relight it and get the entire tank up to temperature right before using your hot water, but that’s a hassle. The most common causes include a loose or defective thermocoupler, a vent downdraft, clogged flue or pilot light assembly or improper gas pressure. Perform those repairs you feel confident about and consult a service technician for advanced repairs and troubleshooting.

Burner Flame Problems

Whether it won’t stay lit, the flame is too high or yellow, the flame appears to float or even emits a noisy, whistling sound, the causes tend to be the same. Dirty orifices, faulty thermocouplers, clogged flues and improper gas pressure are the typical culprits. While cleaning many of the parts is fairly simple, ask a qualified professional for advanced help.

Soot or Scale on Water Heater or in Flue

Soot and scale are the products of combustion. Soot should flow through the flue and exit the home. Excessive buildup of either indicates problems with combustion or an obstruction inside your flue. Clean the flue, similar to a chimney, and keep chemicals away from your water heater. Ensure your gas water heater has an adequate supply of air for ventilation. Consult a repair technician for further assistance.

Preventative Maintenance

While it’s inevitable that your water heater will eventually die, proper maintenance will normally help prolong its life, as well as increase its energy efficiency. The Department of Energy suggests you insulate your water heater – taking care to avoid covering the thermostat on an electric model or the top, bottom, burner and thermostat on a gas model – as well as the first 6 feet of both hot and cold pipes connecting to the water heater.

Inspect your hot water heater completely at least once a year. Performing the inspection during your routine fall or winter maintenance will help you remember to do it. Draining a quart or two of water from your tank a couple times a year will help remove sediment, and checking the T&P valve once a year will help spot malfunctions before they happen.

With any luck, cold showers will be a thing of the past – unless you specifically want one!