Most cases of no hot water in a house trace back to one of three things: a tripped circuit breaker, a triggered electric reset button (called the ECO or high-limit cutout), or an extinguished gas pilot light. Check your electrical panel first. If a breaker has tripped, flip it fully off and then back on — a partially tripped double-pole breaker can look “on” at a glance and fool you. For a gas water heater not heating, confirm the pilot flame is lit before anything else. These two checks alone resolve the majority of hot-water outages without a service call.

Key Takeaways

Most hot-water outages are caused by a tripped breaker, a triggered ECO reset button, or an extinguished pilot light, and all three can be checked and often fixed in under an hour.

Point Details
Check power and gas first Flip the dedicated breaker fully off then on; confirm the gas isolation valve is open before anything else.
Safety before troubleshooting Evacuate and call 911 or the gas utility if you smell gas; shut off power if water is pooled near electrical components.
Reset and relight steps Press the red ECO button on electric units; follow the PILOT-hold-30-to-60-second procedure on gas units.
Annual maintenance prevents outages Flush the tank yearly, inspect the anode every 2–3 years, and keep the thermostat at 120°F.
Empire Plumbing and Air Conditioning Licensed 24/7 emergency water heater repair and replacement for Phoenix-area homeowners, ROC 342717 and 342718.

Table of Contents

What should you do first when you have no hot water?

Before touching the water heater, run through a short safety checklist. Getting this wrong can turn a minor inconvenience into a genuine emergency.

Actions to take immediately:

  • Sniff the air near the water heater and in the utility room. A rotten-egg or sulfur smell means gas is present.
  • Look at the floor around the unit. Standing water near electrical components is a shock hazard.
  • Move children or anyone with limited mobility away from the area until you confirm it is safe.
  • Locate your home’s main electrical panel and the gas isolation valve on the supply line to the heater.

If you smell gas:

  1. Do not flip any light switches or electrical devices on or off.
  2. Leave the house immediately, leaving doors open as you go.
  3. Call your gas utility’s emergency line or 911 from outside or a neighbor’s home.
  4. Do not re-enter until the utility clears the building.

Shutting off power safely: Go to the electrical panel and flip the dedicated double-pole breaker for the water heater fully to OFF. Do not just nudge it. A breaker that trips to a middle position still carries partial voltage. Flip it hard off, wait five seconds, then flip it back on. That two-step reset is the recommended procedure for confirming a clean reset.

Shutting off gas safely: Turn the gas isolation valve on the supply pipe a quarter-turn so the handle sits perpendicular to the pipe. That closes it. Never attempt to relight a pilot if you can still smell gas after turning the supply off — ventilate the area for at least 15 minutes first.

Hand turning gas isolation valve off

Pro Tip: Before any troubleshooting, touch the hot-water outlet pipe and the T&P (temperature-pressure) relief valve at the top of the tank. Cold pipes mean the heater hasn’t run for hours, pointing you toward a power, gas, or ignition fault rather than a downstream pipe blockage.

How to troubleshoot by heater type: electric, gas, and tankless

The fastest path to a fix depends on what kind of unit you have. Here is a type-by-type breakdown.

Electric water heater not heating

  1. Go to the electrical panel and find the dedicated breaker (usually 30-amp double-pole). Flip it fully OFF, then ON.
  2. If the breaker holds, go to the water heater. Remove the upper access panel (two screws, typically). Behind the insulation is a red reset button.
  3. Press the red ECO/reset button firmly until you feel or hear a click. This high-temperature cutout trips when the water overheats and often restores the unit immediately.
  4. Replace the insulation and panel, then restore power at the breaker.
  5. Wait 30–60 minutes. Run a hot-water tap to test.

If the reset button trips again within a day or two, stop resetting it. Repeated trips mean a heating element is shorting or a thermostat has failed. Resetting it repeatedly masks the fault and can damage the tank.

Pro Tip: A “soft” tripped breaker sits between ON and OFF without snapping to the center trip position. It looks on, but the circuit is open. Always flip it hard to OFF first — you’ll feel the difference.

Hand flipping electric water heater breaker off and on

Signs a thermostat or element has failed: water is lukewarm rather than cold (lower element gone), or the reset trips within minutes of being pressed (upper element shorted). Both require a multimeter test or a licensed tech.

Gas storage water heater not heating

  • Confirm other gas appliances (stove burners, furnace) are working. If nothing gas-powered works, the issue is with your gas supply, not the heater.
  • Check the gas isolation valve on the supply line to the heater. The handle should be parallel to the pipe (open).
  • Look through the sight glass or open the burner access cover and check whether the pilot flame is burning. A blue flame the size of a small candle is normal. No flame means the pilot is out.
  • If the pilot is out, follow the relight procedure in the next section.
  • If the pilot is lit but the burner never fires, the thermostat may be set too low or the gas control valve may be failing.

The difference between “no hot water” and “tank ran out”: If you had hot water earlier in the day and it went cold after heavy use, the tank likely ran out and needs recovery time (typically 60–90 minutes for a standard 40–50 gallon unit). A complete outage with no recent heavy use points to a component failure.

Tankless (on-demand) water heater checks

Tankless units display error codes on a small screen. Write the code down and check the unit label or manufacturer manual for the specific meaning before doing anything else.

Beyond the error code:

  • Inlet screen: Turn off the cold-water supply to the unit, remove the cold-water inlet connection, and inspect the mesh filter screen. A clogged screen is one of the most common reasons tankless units fail to fire. Rinse it under a tap and reinstall.
  • Minimum flow: Tankless heaters require a minimum flow rate (often 0.5–0.75 gallons per minute) to trigger ignition. A partially closed valve or a low-flow fixture can prevent the unit from activating.
  • Gas and venting: Confirm the gas supply valve is open and that the exhaust vent is not blocked by debris, a bird nest, or a disconnected pipe.

How to reset an electric heater or relight a gas pilot

Resetting an electric water heater

  1. Turn the dedicated breaker to OFF at the electrical panel.
  2. Remove the upper access panel on the water heater (usually two screws).
  3. Peel back the insulation carefully. Do not cut or tear it.
  4. Locate the red reset button on the upper thermostat. Press it firmly until it clicks.
  5. Fold the insulation back into place and reinstall the panel.
  6. Return to the panel and flip the breaker back to ON.
  7. Wait 30–60 minutes before testing a hot-water tap.

Safety note: If there is water on the floor near the heater, do not restore power until the source of the water is identified and the area is dry. Water and live electrical components are a serious hazard.

Relighting a gas pilot light

The standard relight procedure applies to most gas storage water heaters:

  1. Set the gas control knob to OFF. Wait five minutes for any residual gas to clear.
  2. Turn the knob to PILOT.
  3. Press the knob down (or press the separate red igniter button) while simultaneously pressing the igniter button if your unit has a piezo igniter. On older units without an igniter, hold a long lighter or match near the pilot opening while pressing the knob.
  4. Keep the knob depressed for 30–60 seconds after the flame lights. This heats the thermocouple, which must reach temperature before it will hold the gas valve open.
  5. Release the knob slowly. The pilot flame should stay lit.
  6. Turn the control knob from PILOT to your desired temperature setting (HOT or the 120°F mark).
  7. The main burner should ignite within a few minutes.

If the pilot won’t stay lit after two attempts: The thermocouple is likely failing. It is a thin metal rod that sits in the pilot flame. Replacement costs $15–$30 in parts and is a common DIY fix. If a new thermocouple does not solve it, the gas control valve itself may have failed. On a heater older than eight years, replacing the full unit is often more cost-effective than a gas control valve replacement.

When to stop and call: If the pilot relights but the main burner never fires, if you hear a loud pop or see a flash when igniting, or if the pilot goes out repeatedly within hours, call a licensed plumber or gas technician.

How does sediment buildup affect your hot water supply?

Sediment, primarily calcium and magnesium minerals that precipitate out of hard water, settles at the bottom of a tank over time. In Phoenix-area homes, where water hardness runs high, this happens faster than in most parts of the country.

Sediment buildup inside water heater tank bottom

The practical effects: sediment insulates the burner or lower heating element from the water above it, forcing the unit to run longer and work harder to reach temperature. You may notice the tank making popping or rumbling sounds as water trapped under the sediment layer boils. Eventually, the element overheats and fails, or the burner efficiency drops enough that you get lukewarm water rather than a full outage.

Annual maintenance checklist:

  • Flush the tank: Attach a garden hose to the drain valve at the base of the tank, run the other end to a floor drain or outside, and open the valve to drain 3–5 gallons. This removes loose sediment without a full drain. Do this once a year, more often in hard-water areas.
  • Check the anode rod: This sacrificial magnesium or aluminum rod inside the tank corrodes instead of the tank lining. Inspect it every 2–3 years. If it is less than half its original diameter or heavily coated, replace it.
  • Test the T&P valve: Lift the lever briefly to confirm it opens and releases water, then releases cleanly. A valve that drips continuously afterward needs replacement.
  • Inspect for corrosion: Look at pipe fittings, the base of the tank, and the drain valve for rust staining or mineral deposits.
  • Thermostat setting: Keep it at 120°F. Higher temperatures accelerate sediment formation and create scalding risk; lower temperatures can allow bacterial growth.

Pro Tip: In hard-water areas, consider a whole-house water softener or a polyphosphate inline filter on the cold-water inlet. Either significantly slows mineral accumulation and extends element and anode life.

A full tank flush (draining completely, flushing until clear) should be done by a professional if the tank has not been flushed in several years. Disturbing a heavily sediment-laden drain valve can cause it to fail to reseat, leaving you with a slow drip or an open valve you cannot close.

Is a leak or undersized tank causing your hot-water problem?

Not every lack of hot water traces back to a heating component. Leaks and capacity mismatches are two causes that homeowners often overlook.

Finding leaks:

  • Check the T&P valve discharge pipe for continuous dripping (occasional weeping under pressure is normal; a steady drip is not).
  • Inspect the base of the tank for rust staining, mineral deposits, or a wet ring on the floor.
  • Check all pipe fittings at the top of the unit, both the cold inlet and hot outlet.
  • Look at the floor around the unit for staining that extends beyond the immediate footprint of the tank.

A continuous leak from the tank body itself, as opposed to a fitting or valve, almost always means the tank has corroded through internally. That is not a repairable condition.

Capacity and demand issues:

A 40-gallon tank serving a household of five people running back-to-back showers, a dishwasher, and a load of laundry will run out of hot water regardless of how well the heater functions. If your outage happens consistently after heavy use, the unit may simply be undersized for current demand. Recovery time for a standard electric tank is 60–90 minutes; gas tanks recover faster, typically 30–40 minutes.

Some electric water heaters are on off-peak timers set by the utility. If yours is, the heater may not be allowed to run during peak hours, which can leave you without hot water at predictable times of day. Check with your utility if you suspect this.

Red flags that point to replacement rather than repair:

  • Continuous leaking from the tank body
  • Rust-colored or metallic-tasting hot water
  • Tank age over 10 years (most tank water heaters have a 8–12 year lifespan)
  • Loud rumbling or banging during heating cycles
  • Repeated element or thermostat failures within a short period

When should you call a professional plumber or technician?

Some situations require a licensed pro immediately. Others can wait a day or two. Knowing the difference saves money and keeps you safe.

Call 911 or your gas utility right now if:

  • You smell gas and cannot isolate the supply
  • You see an uncontrolled water leak you cannot stop
  • There is electrical arcing, sparking, or burning smell near the unit
  • The tank is visibly bulging or has ruptured

Schedule a non-emergency service call when:

  • The reset button trips more than once
  • The pilot relights but the main burner does not fire
  • You have replaced the thermocouple and the pilot still will not stay lit
  • Hot water is consistently lukewarm despite correct thermostat settings
  • The tank is over 10 years old and showing any of the red-flag signs above
  • You find a persistent drip at any fitting or valve you cannot tighten

For Phoenix-area homeowners, water heater repair services are available same-day through licensed local contractors.

Typical repair and replacement costs:

Cost ranges reflect typical U.S. market rates and will vary by region, brand, and labor rates.

When hiring a technician, ask for:

  • State contractor license number and proof of insurance
  • A written estimate before work begins
  • Part warranty terms (most quality parts carry a 1-year minimum)
  • Whether the repair requires a permit or triggers a code update (common on older installations)

What does a technician actually check during a service visit?

A licensed tech brings tools and access that make diagnosis faster and more definitive than visual checks alone.

Diagnostic tools and tests:

  • A multimeter checks continuity and resistance on both heating elements. A reading of zero ohms (short) or infinite ohms (open) confirms a failed element.
  • Voltage checks at the element terminals confirm whether power is reaching the element at all, separating an element failure from a thermostat or wiring fault.
  • Gas-pressure testing at the manifold confirms whether the supply pressure is within the manufacturer’s specified range.
  • Combustion analysis on gas units checks burner efficiency and flue gas composition, flagging incomplete combustion or venting problems.
  • Flow-rate measurement on tankless units confirms whether the unit is receiving enough flow to trigger ignition.

Common findings:

  • Failed upper or lower heating element (the most frequent electric water heater repair)
  • Stuck transfer switch between upper and lower thermostats
  • Bad high-limit (ECO) that trips at normal temperatures, indicating a calibration drift
  • Clogged cold-water inlet screens on tankless units
  • Thermocouple failure on gas units
  • Sediment-compromised tanks where the element has burned through the sediment layer and failed

What to expect during the visit:

  • The tech will ask about symptoms, age of the unit, and recent changes (new appliances, increased household size).
  • Expect the diagnostic itself to take 20–45 minutes before any repair work begins.
  • A reputable technician will give you a repair-versus-replace recommendation with a cost comparison before starting work.
  • For water heater troubleshooting that involves gas lines or electrical panels, the tech may need access to both the utility room and the main panel.

The maintenance habit most homeowners skip

Routine annual maintenance is the single most effective thing a homeowner can do to avoid a cold-shower emergency. Most water heater failures are not sudden; they build over months or years through sediment accumulation, anode depletion, and slow corrosion. A technician who inspects the unit annually will catch a failing anode rod, a weeping T&P valve, or a thermocouple showing early signs of wear before any of those become a 2 AM emergency.

For tanks older than seven years, the math shifts. Repair costs on aging units add up quickly, and a gas control valve replacement on a nine-year-old tank rarely makes financial sense when a new unit carries a six-year warranty and costs less than two major repairs. Set the thermostat to 120°F, flush the tank every year, and inspect the anode every two to three years. If rust-colored water or rumbling sounds appear, act immediately rather than waiting for a full failure.

When in doubt about any step, shut off power or gas and call a licensed professional. The risk of getting it wrong is not worth the savings.

Empire Plumbing and Air Conditioning handles hot-water emergencies fast

When the troubleshooting steps above don’t restore your hot water, or when the problem is clearly beyond a DIY fix, you need a licensed technician at your door the same day, not a callback three days later.

Empire Plumbing and Air Conditioning

Empire Plumbing and Air Conditioning has served Phoenix, Scottsdale, Glendale, Peoria, Anthem, Mesa, Tempe, Gilbert, and surrounding communities for over 25 years. The team handles everything from thermocouple swaps and element replacements to full tank and tankless water heater installation for both gas and electric systems. Technicians are available 24/7 for emergencies, hold Arizona ROC licenses 342717 and 342718, and provide written estimates before any work begins. Call for same-day emergency service or request an estimate online.

Sources

Do not wait for a small AC issue to become a major breakdown. If your air conditioner is blowing warm air, making strange noises, leaking water, or failing to cool your home, Empire Plumbing & Air Conditioning can help.

Call 602-275-8400 today to schedule professional Plumbing repair in North Phoenix, AZ.

Serving Phoenix, North Phoenix, Scottsdale, Peoria, Glendale, Anthem, Cave Creek, Mesa, Tempe, Gilbert and surrounding Valley communities.

Click to talk to a live and local scheduler now 602-275-8400