New A. O. Smith Electric Water Heater Not Heating
On this page (7 sections)
The Short Answer: A new A. O. Smith electric heater with no hot water usually has an installation problem, not a faulty tank. Common causes are power not turned on, a tank powered before it was full (which burns out the upper element), a tripped high-limit, or a wiring or plumbing mistake. Allow time to heat and check the breaker. If it was powered empty, leave it off and call the installer.
Give it time first
A standard 40- or 50-gallon electric tank heats slowly compared with gas. A cold tank can take an hour or more to reach temperature, and most electric tanks heat with one element at a time. If the installer just left, wait before deciding something is wrong. Water that is noticeably warming after the first hour is a good sign.
If the heater has an electronic control or display, as on some A. O. Smith and State models, check it for a message. Error meanings depend on the model, so use the manual for the model on your rating plate.
Common causes on a new install
| What you notice | Likely cause | What to do |
|---|---|---|
| No hot water at all, tank cool to the touch after a couple of hours | Breaker off, or wiring not connected | Check the breaker; call the installer |
| No hot water, breaker on | High-limit tripped, or upper element damaged by a dry fire | Installer or technician |
| Power was on before the hot taps ran without sputtering | Upper element likely burned out | Leave it off; call the installer |
| Some hot water, but it runs out fast | Lower element not working, or water connections reversed | Installer |
| Tank outlet hot but taps lukewarm | Mixing valve set low, or a crossover | Check the mixing valve setting |
| Breaker trips | Element or wiring fault | See new heater tripping the breaker |
Why a dry fire is the most common problem
An electric element must be surrounded by water. If power is turned on before the tank is completely full, the upper element, which sits near the top where air collects last, can burn out within seconds. Electric water heater installation instructions call for filling the tank and running a hot water tap until water flows steadily before turning on power.
If you know or suspect the power went on early, don’t keep resetting things. The element needs to be tested and probably replaced. On a brand-new install, that’s normally the installer’s responsibility. See heater turned on without water.
What you can check safely
- Check the breaker. Look for a double-pole breaker labeled for the water heater. If it’s tripped, reset it once. If it trips again, leave it off.
- Check any disconnect switch near the heater.
- Confirm the tank is full. Open a hot tap and let it run. Sputtering or spurting means there’s still air in the tank.
- Feel the hot outlet pipe at the top of the heater after an hour or two. If it’s warm or hot, the heater is working, and the problem is downstream at a mixing valve or fixture.
- Check the thermostat setting if it’s visible on the front of the control. On most electric tanks, the thermostats are behind access covers. Leave those to the installer.
What the installer or technician will check
They will confirm 240 volts reaches the heater, check the wiring connections in the junction box, and test both elements and thermostats. They also check the high-limit and find out why it tripped before resetting it. They confirm the cold supply goes to the cold inlet and the dip tube is in place, and check any mixing valve. If an element was damaged by a dry fire, they replace it and its gasket. Replaced element, still no hot water covers what comes next if a new element doesn’t fix it.
Warranty and responsibility
A tank with installation damage, such as a burned element from powering it empty, is usually an installer issue rather than a manufacturer defect. A genuine factory defect is covered under A. O. Smith’s warranty for that model. Keep the installation date, model and serial number, and the installer’s invoice. For a broader look at new-installation problems that apply to any brand, see brand-new water heater, no hot water.
Frequently Asked Questions
Q: How long should a new A. O. Smith electric take to heat? A: It depends on tank size, element wattage and incoming water temperature. An hour or more from cold is common. Lukewarm water after an hour is often just partial heating. No warmth at all after two hours points to a fault.
Q: Should I turn the temperature up to get hot water faster? A: No. The setting changes the final temperature, not how fast it heats. Higher settings also raise the scald risk.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- A. O. Smith: model and manual lookup (opens in a new tab)Find the instructions for the model on your rating plate; this directory does not verify a particular error-code meaning.
- A. O. Smith: standard electric no-hot-water diagnostic chart (opens in a new tab)Professional diagnostic context for standard electric storage heaters; not instructions to open or test your appliance.
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