Water Heater Not Heating? Here are 5 Ways To Fix It

Before you can fix the problem, you need to know what you are looking at. The troubleshooting steps for a gas water heater are fundamentally different from those for an electric one.

If you have a gas heater, you will see a vent pipe coming out of the top to carry away exhaust, and you will likely hear the sound of a flame or a pilot light. If you have an electric heater, you will usually see a heavy power cable running into the top of the unit and no exhaust vent. Knowing this distinction is critical because it determines where you start your investigation.

Fix 1: Check the Thermostat and Settings

It sounds incredibly simple, but you would be surprised how often a “broken” water heater is just a case of changed settings. This is always the very first thing you should check because it costs nothing and takes seconds.

The Accidental Bump Water heaters are often located in garages, laundry rooms, or closets that are used for storage. It is very easy to accidentally bump the thermostat dial on a gas unit while moving a broom, a box of holiday decorations, or a laundry basket. If the dial gets turned to “Vacation” mode or “Pilot,” the main burner will never ignite to heat the water.

The Temperature Setting Check where the dial is pointing. For most homes, the ideal temperature is between 120 and 140 degrees Fahrenheit. If it is set lower than 120, the water might feel lukewarm by the time it travels through the pipes to your second-floor bathroom. However, be careful not to set it too high, as anything above 140 degrees poses a serious scalding risk, especially for children and the elderly.

The High-Limit Reset Button If you have an electric water heater, the thermostat is hidden behind a metal access panel. However, there is a safety feature you can check without tools. It is called the High-Limit Switch, often referred to as the “red button.”

If the water temperature inside the tank exceeds safe limits, this switch trips to cut the power and prevent an explosion. You can remove the small cover plate and press this red button. If you hear a satisfying “click,” you have reset the system. Power should return to the elements. If it trips again immediately, do not keep resetting it; this indicates a dangerous overheating issue that requires professional Heater Maintenance.

Fix 2: Verify Power and Gas Supply

If the settings are correct, the next logical step is to ensure the unit is actually getting the fuel it needs to do its job. A water heater cannot create heat out of thin air; it needs a steady supply of energy.

Electric Units: The Circuit Breaker Electric water heaters are energy hogs. They draw a significant amount of amperage. If there was a power surge in your neighborhood, or if the heater is older and drawing more power than it should, it may have tripped the circuit breaker in your main electrical panel.

Go to your breaker box and look for a double-pole breaker labeled “Water Heater.” If the handle is in the middle position or flipped to “OFF,” you have found your problem. Flip it firmly to “OFF” and then back to “ON.” If it holds, wait an hour and check your water. If it trips again with a loud pop or a flash, you have a direct short in the wiring or a failed element. Do not attempt to reset it again; call Longhorn Services immediately.

Gas Units: The Gas Valve For gas units, ensure the gas supply valve on the pipe leading to the heater is open. The handle should be parallel to the pipe. If it is perpendicular, the gas is shut off.

You also need to check other gas appliances in your home. If your furnace and stove are also not working, the issue might be with the municipal gas supply to your home, not the heater itself. In that case, you would need to contact your utility provider.

Fix 3: Inspect the Heating Elements (Electric Only)

If you have an electric unit that has power but is still leaving you with cold water, the most likely culprit is a burnt-out heating element. Electric heaters typically have two elements: one at the top of the tank and one at the bottom.

The Top Element The top element is the commander. It heats the water at the top of the tank first. Since hot water rises, this is the water that is drawn off when you open a tap. If the top element fails, the computer or thermostat will never trigger the bottom element. The result? You get absolutely no hot water at all. It is a complete shutdown of comfort.

The Bottom Element The bottom element does the heavy lifting of heating the incoming cold water. If the top element works but the bottom one fails, you will have what we call “short showers.” You will get hot water for maybe five or ten minutes, but because the bottom of the tank is cold, the supply runs out incredibly fast.

Testing the Elements Diagnosing this requires a multimeter and working with live electricity, which we do not recommend for the average homeowner. A technician from Longhorn Services will test the resistance (ohms) of each element. A healthy element has continuity. A broken element involves a severed internal wire, meaning the electricity cannot complete the circuit to generate heat. Replacing an element is a standard and affordable Heater Repair that restores your unit to full functionality.

Fix 4: The Pilot Light and Thermocouple (Gas Only)

For gas water heaters, the pilot light is the heartbeat of the system. If the pilot goes out, the main burner cannot ignite.

Why Pilots Go Out Drafts are a common enemy. If your water heater is in a windy attic or a garage with a drafty door, a sudden gust can blow out the small flame. You can try relighting it by following the instructions printed on the side of the tank. This usually involves holding down a knob to feed gas to the pilot while clicking a piezo igniter.

The Thermocouple Factor If you can light the pilot, but it goes out the moment you let go of the knob, your thermocouple is likely dead. The thermocouple is a safety sensor that sits right in the flame. Its job is to tell the gas valve, “I feel heat, so there is a flame, keep the gas flowing.”

If the thermocouple is broken or dirty, it cannot send that signal. The gas valve assumes the flame is out and shuts off the gas to prevent a leak. Replacing a thermocouple is one of the most common repairs we perform at Longhorn Services. It is an inexpensive part, but installing it requires precision to ensure it sits correctly in the flame path.

Electronic Ignition Newer, high-efficiency gas units do not have a standing pilot light. They use an electronic spark or a hot surface igniter, similar to a furnace. If these fail, you will often see an error code flashing on a small LED screen on the gas valve. These codes can tell you if the issue is air supply, ignition failure, or a blocked vent.

Fix 5: Flush Out Sediment Buildup

Sometimes the heater is working, but it can’t transfer the heat to the water. This is a chronic issue in North Texas due to our hard water.

The Insulating Layer Minerals like calcium and magnesium dissolve in water. When that water is heated in your tank, those minerals precipitate out and settle at the bottom. Over time, they form a thick layer of rock-hard sediment.

In a gas heater, the burner is at the bottom. It has to heat through the metal tank, then through inches of sediment, just to reach the water. This acts as a massive insulator. You are burning gas to heat rocks, not water. You might hear loud popping, banging, or rumbling noises coming from the tank. That is the sound of steam bubbles trapped under the sediment layer exploding.

The Solution: A System Flush To fix this, you need to perform a sediment flush. This involves connecting a garden hose to the drain valve at the bottom of the tank and opening it to let the water pressure blast the sediment out into your driveway or a drain.

However, if the sediment has been building up for years, the drain valve might be clogged, or the chunks might be too big to pass. In severe cases, the sediment can trap so much heat that it weakens the steel tank, leading to leaks. Regular Heater Maintenance prevents this buildup, but if your hot water heater is not heating due to sediment, a flush might be the last-ditch effort before replacement.