Why Is My Hot Water Not Working?
QUICK ANSWER
Hot water failures are usually one of four issues: a tripped circuit breaker (electric), pilot light out (gas), failed thermostat or heating element, or heavy sediment buildup inside the tank. Check each in order before assuming the water heater needs full replacement.
When the hot water stops working, the cause is usually something simple and fixable rather than a failed tank. Electric and gas water heaters each have their own common failure points but the troubleshooting follows the same logic: start with the easiest fixes (power, pilot, breaker) and work toward the harder diagnostics. Here is the order to check and what each symptom means.
What are the most common causes of no hot water?
For electric water heaters, the most common causes are a tripped breaker, a failed upper or lower heating element, or a faulty thermostat. For gas water heaters, the most common causes are a pilot light that has gone out, a failed thermocouple (the safety sensor next to the pilot), or a closed gas supply valve. Both types share two more common issues: heavy sediment buildup at the bottom of the tank insulating the water from the heat source, and an age-related tank failure. The Department of Energy maintains general information on storage water heater operation.
How do you check a gas water heater?
First verify the gas supply valve is fully open (the lever should be parallel to the gas line, not perpendicular). Look at the pilot light access window at the base of the tank. If the pilot is out, follow the relighting instructions printed on the heater label exactly. If the pilot will not stay lit, the thermocouple is likely failing (a 15 dollar part). If the pilot stays lit but the burner does not fire, the gas control valve or thermostat may be the issue. Strong gas smell at the tank? Stop and call the gas company.
How do you check an electric water heater?
Check the breaker panel first. Water heater breakers are usually labeled and are double-pole (40 amp typical). If tripped, flip fully off then back on. If the breaker trips again, stop and call an electrician. If the breaker is fine, the issue is likely a failed heating element or thermostat. Press the red reset button on the upper thermostat (behind the access panel on the side of the tank). Confirm the panel cover is screwed back on before restoring power. Replacement elements run 20 to 40 dollars and require draining the tank.
When should you call a pro?
Call a professional for any gas leak (call the gas company immediately, not a plumber), for repeated breaker trips on an electric heater, for any visible water leak from the tank itself, or for a water heater over 10 years old that has failed (replacement is usually more cost-effective than repair). Also call if you see significant corrosion on the tank exterior, if the water has turned brown or rust-colored, or if you hear loud banging or rumbling sounds even after sediment flushing.
Hot water failures usually trace back to power, pilot, thermostat, or sediment issues. For electric heaters, check the breaker and reset button first. For gas, check the gas valve and pilot light. Replace heating elements, thermocouples, or thermostats if those test bad. Call a pro for gas leaks, persistent breaker trips, or tank-level leaks. Most fixes are under 50 dollars and an afternoon of work.
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