Brand New Water Heater Has No Hot Water
On this page (6 sections)
The Short Answer: When a brand-new tank gives no hot water, the cause is almost always the startup, not a defective heater. It may not have had time to heat. A valve may still be closed, or the breaker or gas still off. On electric models, an element may have burned out because it was powered before the tank was full. Check the startup steps before asking for a warranty replacement.
Give it time first
A new tank starts full of cold water. As a rough guide, a 40- or 50-gallon gas tank takes around an hour to heat from cold. A standard electric tank with 4,500-watt elements typically takes one and a half to two hours or more, depending on its size and how cold the incoming water is. If you’ve waited that long and the water is still cold, work through the checks below.
Checks in order
| Check | What you’re looking for |
|---|---|
| Tank filled and air purged | After installation, a hot tap should run a steady stream with no spitting air |
| Cold inlet valve open | Handle in line with the pipe, or turned fully open |
| Hot outlet path open | Any shutoff on the hot side open |
| Electric: breaker | Fully on. A double-pole breaker for most 240-volt tanks. Reset once if tripped |
| Gas: supply valve and control | Supply valve open, control turned from OFF to the setting the lighting label describes, pilot lit or ignition started |
| Temperature setting | Not left on VACATION or the lowest setting |
| Is the tank hot but the taps cold? | If the tank jacket or hot pipe is warm, the heater is working and the problem is in the plumbing. See below |
The dry-fire problem on electric tanks
If an electric tank was switched on before it was completely full, the upper element can burn out within seconds. The tank then stays cold even though everything else is set correctly. If you suspect this happened, leave the breaker off and tell the installer. Testing and replacing the element happens behind the electrical covers and is a job for a qualified person. Don’t reset the high-limit switch, which is also behind the cover, as a test. See water heater turned on without water.
When the tank is hot but the taps aren’t
If the hot outlet pipe near the tank is hot but fixtures stay cold or lukewarm, look at the plumbing:
- a mixing valve at the heater set too cool
- hot and cold connections swapped at the heater
- a shower or faucet cartridge letting cold water cross into the hot line
These are installer corrections. The heater itself is fine. If the water is warm rather than cold, see brand new water heater only warm.
When to call the installer back
Call the installer back if:
- the breaker trips again (see new hot water heater keeps tripping breaker)
- the gas pilot or burner won’t light after one attempt following the label
- water is in the drain pan (see new water heater has water in the pan)
- you suspect the tank was powered empty
Most new-installation faults are covered by the installer’s workmanship warranty. Manufacturing defects are covered by the heater warranty.
Frequently Asked Questions
Q: Can a brand-new water heater be defective out of the box? A: It happens, but rarely compared with startup problems. A failed element after a dry start isn’t a factory defect. Have the installer confirm the cause before you file a warranty claim.
Q: My new gas heater’s pilot won’t stay lit. Is that air in the line? A: After a new installation, air in the gas line can delay lighting. Clearing it means working on gas fittings, so the installer or a gas technician must do it. Don’t open fittings yourself.
Q: Should I turn the thermostat higher to speed it up? A: No. A higher setting doesn’t heat the tank faster. It just keeps heating longer and increases 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: 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.
- PG&E: recognizing and responding to a gas leak (opens in a new tab)Emergency actions for suspected fuel-gas leaks.
Editorial standards and corrections · Prepare a useful service request