A water heater that is on but not heating is a different problem from one that leaks or makes noise, and the fix depends on whether it runs on gas or electricity. Start by working out which one you have and what the symptom is, then use the sorting below. If you want the bigger picture on repair choices, see our hub on water heater repair in Burbank.
Why is my hot water heater not heating?
On a gas tank the common culprits are an extinguished pilot, a worn thermocouple, a closed gas valve, or a dead gas control. On an electric tank, look at a tripped breaker, a high-limit cutout that has opened, a dead element or a dead thermostat. In an older tank, sediment can weaken either type.
First, work out which kind you own. A gas heater has a burner compartment low on the tank and a flue pipe rising out of the top. An electric heater has no flue and has one or two panels on the side with wiring behind them. If you cannot tell, the tank's label states gas or electric.
Sorted by symptom:
| What you see | Gas tank | Electric tank |
|---|---|---|
| Totally cold, no sign of life | Pilot out, gas valve closed | Breaker tripped, reset button popped |
| Warm but never hot | Low thermostat, sediment, weak burner | Lower element or thermostat failed |
| Hot for a short time, then cold | Sediment, dip tube, tank too small | Lower element failed, upper element working |
| Hot at the heater, cold at the faucet | Pipe problem, crossover, closed valve | Same |
That last row is important. When the tank is hot to the touch near the outlet pipe yet faucets run cold, the heater is fine and the trouble lies in the pipework.
What can I safely check first?
Start with the power or gas, then the dial, then a second faucet. These checks need no tools and carry little risk: the breaker, the gas supply valve, the thermostat setting and the pilot window. Stop at any gas smell, any wiring behind a panel, or any leaking tank.
In this order:
- Electric: locate the heater's own double breaker in your panel. If it has tripped, push it fully off and then on one time. Should it trip again, keep it off and phone for help.
- Gas: make sure the gas supply valve at the heater is open, and look through the pilot window for a blue flame. If the flame is out, use the relighting steps on the label, and only when you smell no gas.
- Both: look at the temperature dial. A vacation or low setting often turns up after a house sitter or a move.
- Both: run the hot side at two different taps. If one is hot and one is cold, the heater is not the culprit.
- Both: put a hand on the pipe leaving the tank's top. If that outlet pipe is hot and the taps are cold, the fault is downstream.
Whenever there is a gas smell, exit the house first. From outside, ring SoCalGas at 1-800-427-2200, and dial 911 if anyone may be hurt. With electric units, do not open a panel until the breaker is off and the circuit is confirmed dead.
Is it the thermostat, the element or the pilot?
For electric tanks, suspect the element or the thermostat; for gas tanks, suspect the pilot assembly or the gas control. Elements burn out through scale and age, thermostats fail stuck on or off, and pilots die from drafts or a worn thermocouple. A plumber confirms which with a meter or a flame check.
Each one has a page of its own:
- Faults with the electric thermostat: thermostat replacement.
- An electric heater giving cold water: no hot water from an electric heater.
- Gas pilot trouble: pilot light repair.
- Gas heater generally: gas water heater repair.
- Gas control valve faults: gas valve replacement.
Hardness matters here. Valley water carries minerals that settle as scale on elements and the tank floor, so the harder the water, the sooner elements fail and the more sediment insulates the flame. Burbank Water and Power, Glendale Water and Power and LADWP each publish a water quality report with the numbers for your supply.
What if the whole house has hot water trouble, not just one tap?
The heater, the fuel supply or a main hot valve is the likely cause. If the shower alone is cold, go to no hot water from the shower, and if only the kitchen tap is cold, go to no hot water at the kitchen sink. For a washer that only gets cold water, see washing machine with no hot water.
Water that is hot briefly and then runs cold is a capacity problem. A broken dip tube lets cold water blend in at the top of the tank, and sediment shrinks the volume of hot water the tank holds. Our guide on dip tube replacement explains that one, and why you have no hot water lists the causes house-wide.
A note on the phrase "hot water heating." Some older homes, mostly in colder climates, use a boiler to warm radiators. That is rare in Burbank. If yours is a hydronic system with a boiler and the radiators are cold, that is a heating service call, not a water heater one. Say so when you book.
When is it time to replace the heater instead?
Replace it when the tank leaks, is rusted through, rumbles from heavy sediment, or is old enough that another fault is likely soon. Repairs suit a young tank with a single failed part. A tank body that leaks is beyond repair, and the answer is a new water heater installation.
For guidance on age, read how often a water heater needs replacing. If you decide to replace, hot water heater replacement covers the process, and the permit page explains who issues it at your address. Tankless water heaters are an option, covered on electric versus tankless.
For same-day help with no hot water, see emergency hot water heater repair.
How do I get it looked at?
Give the plumber the fuel type, the heater's age, the symptom and the checks you have done. Use our quote page to book, and the local plumber sends a written price ahead of the job. Browse every service on the Lankershim Plumbing home page.
Before agreeing to anything, look up the contractor's license number at the state licensing board for California contractors. Each step from enquiry to finished job is on the how it works page.
Questions people ask
The heater runs but the water is cold. Why?
Check whether the tank is actually hot near the outlet. If it is, the fault is in the pipes or a closed valve. If the tank is cold, a gas unit may have a bad thermocouple or gas control, and an electric one may have a dead element or thermostat. A plumber can test to find out which.
How long does it take for a water heater to heat up?
A typical 40 to 50 gallon tank takes an hour or more to heat from cold, depending on the fuel and the size. Gas tanks usually recover faster than electric ones. If it has been several hours and the water is still cold, something is wrong beyond normal heating time.
Why is my hot water short-lived?
The tank may be emptying because of sediment, a broken dip tube, a dead lower element on an electric unit, or a tank too small for your household. Note whether hot water returns within an hour. If recovery takes far longer than it used to, have a plumber examine the heater.
Is it safe to reset a water heater on my own?
On an electric unit, you can press the red reset button once the breaker is off, and you can reset a tripped breaker one time. On a gas unit, you can relight the pilot using the label's steps if there is no gas odor. When a reset does not hold, stop, since repeated resets only mask a fault.
What questions should I put to a plumber when the heater will not heat?
Find out what they will test, how they decide between repair and replacement, what the diagnosis costs, and whether the price is put in writing beforehand. Also ask if a permit applies should replacement be the answer, and who files it.
References
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