Once a year, a gas tank water heater needs its relief valve tested, its vent checked for leaks and draft, its combustion air openings cleared, and its burner and gas control inspected by a qualified technician. Flush sediment and check the anode on schedule too. Phoenix hard water makes the sediment step matter more.
What's on the yearly gas checklist?
Six items, split between you and a technician. This list follows Bradford White's maintenance section for atmospheric-vent gas tanks, the standard kind with a metal flue pipe on top. Your heater's own manual is the final word, so check its intervals against this.
| Task | How often (per the manual) | Who |
|---|---|---|
| Check the gas control works | Annually | Technician |
| Clean burner, orifice and combustion chamber | Annually | Technician |
| Inspect the vent for exhaust leakage | At least once a year | Technician (you can do a visual check) |
| Keep combustion air slots open and clear | Ongoing | You |
| Look at the burner and pilot flames | Twice a year | You |
| Test the temperature and pressure relief valve | At least once a year | You |
Two tank items run on their own clocks. The same manual says to drain off a gallon of water monthly to remove sediment, and to inspect the anode rod every 2 years, more often with softened water. A. O. Smith's maintenance guide recommends inspecting the anode once a year. Different brands, different intervals, so go with your model's book.
What does the technician check on the gas side?
The parts that burn gas and carry exhaust, because mistakes there can hurt people. Bradford White lists three technician jobs.
The gas control. The manual says to annually check the operation of the combined gas control. That's the valve and thermostat unit on the front of the tank.
The burner and combustion chamber. Once a year, the manual has the technician remove the inner door and main burner assembly, clean the orifices, check the burner ports for debris, and wire brush or vacuum the combustion chamber to remove scale and debris. The manual also calls for inspecting the inner door gasket, and replacing it as needed, any time that door is removed. This is not a homeowner job. The manual warns not to attempt repair of the gas control, burners or gas piping yourself.
The vent. The manual says the vent system must be inspected at least once a year to ensure against leakage of exhaust products. On an atmospheric heater, that typically means checking that the draft hood sits right, the flue pipe joints are tight and sloped up, and exhaust actually goes up the flue. A vent that spills exhaust can put carbon monoxide in the house. Our page on whether a water heater can cause carbon monoxide explains the warning signs.
What can you do yourself?
The flame look, the air check, the relief valve test and the sediment flush are fair game for most homeowners.
Look at the flames twice a year. Bradford White says to bi-annually conduct a visual check of the main and pilot burner flames through the sight window. The manual says the main burner flame should light smoothly from the pilot, and it warns elsewhere that a short air supply can cause a yellow, luminous flame and sooting. If you see sooting or anything odd, the manual says to shut the heater down by turning off the gas per its instructions and call for service.
Keep the air openings clear. The manual says the flow of combustion and ventilation air must not be restricted, and to keep the slots in the jacket clear of dirt and dust. In a Phoenix garage that means brushing off the dust that settles around the base, and never stacking boxes or storage against the heater. A. O. Smith's annual checklist also includes cleaning air intake vents.
Keep flammables away. The manual says to keep the water heater area clear and free from combustible materials, gasoline and other flammable vapors and liquids at all times. Garages are where the gas can, paint and pool chemicals tend to live. Move them.
Test the relief valve once a year. Bradford White says to lift the lever at the top of the valve several times until it seats properly without leaking. Expect a burst of hot water, so stand clear. If the valve drips afterward, see why a water heater relief valve leaks.
How does Phoenix water change the routine?
It moves sediment to the top of the list. The City of Phoenix's 2025 water quality report lists total hardness at 10 to 17.6 grains per gallon. Those minerals settle on the bottom of a gas tank, right over the burner, where they insulate the water from the flame and cause the popping and rumbling many Valley owners hear.
That's why the monthly gallon drain in the manual matters here, along with a fuller flush. A. O. Smith notes that most tank heaters need flushing at least once per year, and more often in hard water areas. Our guide on how often to flush a water heater in Phoenix walks through the steps, and what that popping noise means explains why sediment gets loud.
When should the yearly checkup turn into a repair call?
Right away, and don't wait for the annual visit, if you see any of these:
- A gas smell. Leave the house and call the gas company from outside.
- Soot, scorch marks or melted plastic near the draft hood, or a yellow, lazy flame.
- A pilot that won't stay lit, covered on our pilot light troubleshooting page.
- Rust or water around the base or the burner opening.
- Any heater that was near a flammable vapor spill. Bradford White says to replace the water heater if it was involved in a flammable vapors incident.
HQ services gas water heaters across the Valley, including the burner, venting and relief valve checks, with upfront pricing before any work starts. Our water heater service page has the details.