Know your system · Water heater
No hot water: safe checks before you call
Short version: no hot water usually comes down to a few things: a tripped breaker, a pilot light that went out, a temperature dial that got turned down, a tripped reset button, or a heating element that quit. Start with the dial and the breaker. If a check means opening an electrical cover you are not comfortable around, or gas work beyond relighting a pilot by the heater's own instructions, have a pro take it from there.
- Gas and electric heaters fail in different ways, so some checks only apply to one kind. The label on the heater says which you have.
Electric: check the breaker first
If the panel is wet, damaged, hot, buzzing, sparking or smells burnt, stay away. Do not touch it or reset a breaker. Call an electrician. For smoke or fire, move away and call emergency services.
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- A water heater usually has a double breaker: two slots side by side with one handle tied across. A tripped one sits in the middle, out of line with the others.
- Push it fully off, then firmly back on, once. If it trips again, leave it off and call a pro. If the panel is wet, damaged, hot, buzzing, sparking or smells burnt, stay away.
Find the breaker labeled water heater. It is usually a double breaker: two slots with one handle tied across. A tripped one sits in the middle, out of line with the others. Push it fully off, then firmly back on, once. If it trips again, leave it off and call a pro. A breaker that trips again is pointing to an electrical problem, and another reset will not fix it. Do not guess which breaker feeds the heater.
Electric: the reset button
Electric water heaters have a red reset button on the upper thermostat. It trips when the water gets too hot. Follow the heater's own reset instructions. Turn off power at the correctly identified breaker before opening any access panel. Switching a breaker off does not prove an exposed wire is safe to touch. If you cannot safely identify the circuit or reach the reset without touching electrical parts, leave it to a pro. Stop and call a pro if the water is scalding hot, the tank is hissing or leaking, or you smell burning. Replace the access covers before restoring power, then allow the recovery time in the manual. If it trips again, call a pro: the heater has a problem that another press will not fix.
Gas: the pilot light
To see the pilot, take off the outer cover at the bottom of the heater, just under the gas control. Most covers lift off, and some need a screwdriver. Behind it is a small glass window. Look through the glass: a small blue flame wrapped around the tip of the thermocouple (the thin copper rod beside the pilot) means the pilot is lit. Do not open the inner door behind the glass. It is sealed. Put the outer cover back on when you are done.
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Read the field notes
- To see the pilot, take off the outer cover at the bottom of the heater, under the gas control. Most lift off; some need a screwdriver. Look through the small glass window behind it. Do not open the inner door behind the glass; it is sealed. Put the outer cover back on when you are done.
- Lit: a small blue flame, maybe a little yellow at the tip, wrapped around the tip of the thermocouple (the thin copper rod beside the pilot). The big burner below only lights when the heater is heating.
- Gas controls come in two common kinds: a knob type, with a gas knob on top (OFF, PILOT, ON), a temperature dial and a red igniter button, and an electronic type, with one round knob, a status light and a square igniter button. Your heater's lighting label says which steps to follow.
- Only for a heater with a standing pilot. Follow the lighting and waiting steps printed on that heater exactly. Do not use them on a model with a hot surface or spark igniter.
- If the pilot goes out again, or went out after roof work or a storm, leave it off, call a pro and make sure your CO alarms work. Smell gas: get out and call from outside.
If your heater has a standing pilot and it is out, follow the lighting and waiting instructions printed on that heater exactly. If you are in doubt at any step, stop and call a pro. Do not apply those steps to a model with a hot surface or spark igniter. If the pilot goes out again after you relight it, leave it off, call a pro, and make sure your CO alarms work. A pilot that keeps going out needs a technician to find out why; relighting it again will not fix it. A pilot that went out after roof work or a storm can mean a venting problem: do not relight it, and contact a qualified professional. During an active CO alarm or suspected exposure, follow the emergency steps above; do not relight the pilot or stay to troubleshoot. If you smell gas at any point, leave the house and call your gas utility or 911 from outside. Do not operate switches, open windows, or go back in.
Both: the thermostat setting
Check whether the dial got turned down. If it was, set it back to HOT and give the tank time to heat back up. Turning the dial up can sometimes help for a little while, but hotter water raises the risk of scalding, so be careful. If the dial is already at HOT and the water is still not hot, have a pro take a look. The U.S. Consumer Product Safety Commission (CPSC) recommends 120°F to reduce tap-water scald risk. Even 120°F water can burn with prolonged contact, and hotter water burns much faster. Follow the heater's instructions. If your household needs a different storage temperature, ask a qualified pro about scald protection rather than guessing at the dial.
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- Dial marks vary by maker. CPSC recommends 120°F to reduce scald risk; on many gas heaters that is near the HOT mark, but check your heater label or manual. Electric heaters set temperature behind access panels; leave that to the manual or a pro.
- A tank needs time to heat back up after the dial is set right; the heater manual lists how long.
- Turning the dial up can sometimes help for a little while, but hotter water raises the risk of scalding. If the dial is at HOT and the water is still not hot, have a pro take a look.
When it is the heater itself
On an electric heater, hot water that runs out fast can mean a heating element has failed, as Lennox notes, though how much hot water you use and the settings matter too. A pro can test it. Sediment in the tank can lower efficiency and make popping or rumbling noises. If your tank is more than 6 years old and has not been flushed in the last few years, flushing it is not recommended. Built-up sediment can be part of what keeps an old tank sealed, and stirring it loose can start a leak. If the tank itself is leaking, have a pro look at replacing it. Lennox gives about 8 to 12 years as a typical tank life, but that is an average, not an expiration date for your heater.
Where to go from here
If you still do not have hot water after these checks, then it is recommended to have a pro evaluate the situation and mention what you have done so far. This will help get the problem solved quicker and get the hot water back.
Before an emergency, make a household exit plan so everyone knows where to go and who needs help.
Sources
The advice against flushing a tank older than about 6 years that has not been flushed in the last few years comes from field experience.
Lennox supports the troubleshooting checks and its typical 8-12 year tank lifespan. Lennox is best known for heating and cooling; it began selling its own line of water heaters in 2026 through a joint venture with Ariston. Its suggested 125-140°F range conflicts with CPSC's scald guidance, so this page uses CPSC's 120°F recommendation instead. Recovery time and reset steps depend on the heater's own instructions.
CPSC's CO questions and answers support the evacuation, outside emergency call, headcount and no-re-entry steps.
CO response checked October 9, 2026. Troubleshooting and scald guidance last rechecked September 29, 2026.
The Electrical Safety Foundation International (ESFI) supports the heat, buzzing, sparks and burning-smell warning signs. The wet or damaged panel limit and the no-repeat-reset limit are conservative limits, not manufacturer text. Electrical warning signs checked September 30, 2026.