Two different problems
No hot water at all usually means the heater is not heating: the burner has not lit, an element or thermostat has failed, a safety switch has tripped or the power or gas is off. Hot water that runs out too soon is a different complaint. The heater works, but it cannot keep up, because sediment has taken up space in the tank, a dip tube has broken, one element has failed or the household now uses more water than the heater was sized for.
Telling these apart early saves time. Note whether every hot tap is cold, whether the water gets warm and then fades, and whether the problem started suddenly or crept up over months.
Safe checks anyone can do
Stop at any point if you smell gas: leave and call 911 or SoCalGas from outside.
Symptoms and likely causes
| What you notice | Gas tank | Electric tank | Tankless |
|---|---|---|---|
| No hot water at all | Pilot out, thermocouple or gas valve failed | Breaker tripped, high-limit switch tripped, both elements out | Error code, ignition fault, gas or power supply |
| Runs out fast | Sediment buildup, broken dip tube | Lower element failed, sediment | Flow demand above what the unit can heat |
| Lukewarm only | Thermostat set low, burner problem | Upper element or thermostat failed | Scale on the heat exchanger, flow sensor |
| Hot then cold bursts | Rare on tanks | Rare on tanks | Minimum flow not reached, scale, cold-water sandwich |
When to call
- IfThe breaker trips again after one resetThenLeave it off. There is likely a shorted element or wiring fault for a licensed professional to find.
- IfThe pilot will not light or will not stay litThenCall a licensed plumber. A thermocouple, flame sensor or gas valve may need replacing.
- IfHot water runs out sooner each yearThenAsk about sediment, the dip tube and the heater's age before deciding on a repair.
- IfThere is a gas smellThenLeave now and call 911 or SoCalGas from outside.
What to ask the plumber
- What part failed, and is it worth replacing at this heater's age?
- Is sediment limiting how much hot water I get?
- Is my heater the right size for the household now?
- If you recommend replacement, what would the quote include?
Common questions
Why does my hot water run out faster than it used to?
Common causes are sediment from hard water filling the tank, a broken dip tube mixing cold water into the hot, or a failed lower element on an electric heater. More people or new fixtures in the house can also outpace an older heater.
Can I relight the pilot myself?
Many gas heaters have lighting instructions on the label, but if you are unsure, smell gas, or the pilot goes out again, stop and call a licensed plumber or SoCalGas.
My electric heater's breaker keeps tripping. Is that dangerous?
Repeated tripping signals a fault such as a shorted element or damaged wiring. Leave the breaker off and have it checked rather than resetting it again.
General information for Brea, not a quote or professional advice. In an emergency, call 911.