A. O. Smith Water Heater Troubleshooting Guide
On this page (8 sections)
The Short Answer: Start by identifying which kind of A. O. Smith heater you have, because gas tanks, electric tanks, hybrid heat pumps, and tankless units fail in different ways. Then check the basics for that type: gas supply and the status light, the breaker, the display code, or water flow. Most problems show a light pattern or code that narrows the cause before anyone takes a panel off.
Identify your heater
The rating plate on the side of the tank or unit lists the model number, fuel, and input. A. O. Smith also builds heaters sold as State, American, Reliance, and store brands, and many share controls and parts. The guides for those brands, such as State Select gas and American water heater troubleshooting, cover the same families.
| What you see | Type | Where to start |
|---|---|---|
| Gas control with a knob and a status light, pilot viewing window | Standing-pilot gas tank | Status light and pilot |
| Plugs into an outlet, motorized damper on the flue | Ultra Low NOx gas tank | Gas control light and LDO module light |
| Blower on top, plastic vent pipe | Power-vent gas tank | Blower, vent, status code |
| Two access panels on the side, no gas line | Electric tank | Breaker, then any display code |
| Unit with a fan and filter on top of the tank | Hybrid heat pump | Display code and filter |
| Wall-mounted box with a digital remote | Gas tankless | Error code on the remote |
Gas tank models
A. O. Smith’s standing-pilot gas controls flash a status light: a single repeating flash is normal, and counted flashes mean a fault. Our guides cover what the green light means, steady, missing and slow light patterns, and three flashes. Before calling, check:
- The gas supply valve to the heater is open and other gas appliances work.
- The pilot is lit. If not, relight once following the label; A. O. Smith’s controls need 10 minutes between attempts.
- The base of the heater and its air openings are clear of lint, dust, and stored items, and no flammable liquids are nearby.
- On power-vent models, the outdoor vent termination is clear.
If a reset button keeps tripping, see A. O. Smith reset keeps tripping. If you suspect the control itself, see A. O. Smith gas control valve.
Electric tank models
Most no-heat problems on an electric tank are a tripped breaker, a failed element, or a thermostat or high-limit fault. Check that the heater’s double-pole breaker is fully on; reset it once if it has tripped, and leave it off if it trips again. If your model has a digital display, note the code and look it up in the manual for your model; we cover reported meanings of E02 and E55. Testing elements and thermostats involves 240-volt wiring and is a technician’s job. If hot water runs out fast, the lower element is a common cause; see water heater element not working.
Hybrid heat pump models
The display explains most problems. A. O. Smith’s earlier hybrid manual lists codes such as SF (dirty air filter), Edr (tank not full), EUC and ELC (upper and lower element), and ICE (defrosting, normal). Owners can clean the filter, check the mode is not set to Vacation, and keep the condensate drain clear. See A. O. Smith hybrid problems for both code styles and humming noise for sounds.
Tankless models
A. O. Smith’s gas tankless models show a numeric code. On the 110, 310 and 510 models, for example, A. O. Smith lists 11 as ignition failure, 12 as loss of flame, and 99 as imperfect combustion. A lockout clears by cycling power, which only helps once the cause is fixed. See A. O. Smith tankless reset and A. O. Smith tankless with no hot water.
Leaks on any model
Dry the area and look again before assuming the tank has failed. A. O. Smith’s bulletin on puddles around a heater (opens in a new tab) explains that most water comes from connections, the relief valve, condensation, or other appliances. A leak from the tank shell itself means replacement; see water leaking from the bottom of the tank.
When to repair and when to replace
Pilot assemblies, thermopiles, elements, thermostats, filters, and sensors are routine repairs. A gas control, a hybrid compressor, or a tankless heat exchanger costs more; weigh the heater’s age (see how to tell a water heater’s age) and warranty before approving one. A leaking tank is always a replacement.
Frequently Asked Questions
Q: Where do I find the manual for my A. O. Smith heater? A: A. O. Smith’s support page (opens in a new tab) lets you look up documents by model number. Many heaters also have the manual in a pocket on the side of the tank.
Q: Is my A. O. Smith the same as my State or American heater? A: Often the controls and parts are shared, but model numbers and code tables can differ. Always use the documents for the model number on your rating plate.
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 service handbook 327726: residential FVIR gas water heaters (opens in a new tab)A. O. Smith GCV, GCVH, GVR, GCVL, GVRL, GCVT and related series 300/301 standing-pilot gas models.
- A. O. Smith hybrid electric heat pump water heater use and care guide (326880) (opens in a new tab)Earlier A. O. Smith hybrid heat pump models with letter codes.
- A. O. Smith on-demand water heater owner's guide: 110, 310 and 510 models (opens in a new tab)A. O. Smith 110, 310 and 510 gas tankless models.
- 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 technical bulletin 51: puddles around a heater (opens in a new tab)Common water-leak sources and the distinction between fittings and a failed tank.
- PG&E: recognizing and responding to a gas leak (opens in a new tab)Emergency actions for suspected fuel-gas leaks.
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