State parts are sold through AO Smith distribution (Ferguson, Hajoca, Winsupply) plus authorized State installers. Amazon stocks high-volume DIY parts (anode rods, elements, thermostats, thermocouples). State and AO Smith Signature share most internal parts — same factories produce both.
The State parts catalog
- Anode rod — protects the tank from corrosion. The single highest-ROI maintenance task. Replace every 4-7 years
- Heating element — electric tanks only. Upper and lower. DIY-replaceable
- Thermostat — electric upper and lower; gas integrated into the gas valve
- Gas valve — gas units; integrated with thermostat and ECO. Dealer-only replacement
- Thermocouple — standing-pilot gas units. Behind most 2-flash faults. DIY-replaceable
- Igniter — electronic ignition gas units
- Dip tube — broken dip tube = hot water runs out fast. DIY-replaceable
Where to buy
- Amazon — anode rods, elements, thermostats, thermocouples, dip tubes
- Lowe\'s — strong State parts presence (since State is Lowe\'s primary water heater brand)
- Plumbing wholesaler — Ferguson, Hajoca, Winsupply (AO Smith distribution)
- State authorized installer — full catalog access
Common multi-part repair kits
- Annual maintenance kit: anode rod + T&P valve + drain valve cap. $40-60
- Pilot rebuild kit: thermocouple + pilot tube gasket. $20-40
- Element + thermostat kit (electric): matched pair. $60-100
State vs AO Smith Signature parts compatibility
Most State and AO Smith Signature parts are interchangeable — same manufacturing facilities produce both. Exceptions:
- Gas valves are model-specific (check the part number on the valve before ordering)
- Electronic ignition modules differ between State and Signature trim levels
- Premier Hybrid heat pump compressors are specific to the HPX chassis (Voltex compressors aren\'t direct swaps)
Warranty considerations
State parts warranty: 6 years on ProLine, 8 years on XE, 10 years on Premier Hybrid. OEM State/AO Smith parts during warranty period maintain coverage; aftermarket parts void the warranty on the affected system.
Bottom line
Anode rod, element, thermostat, thermocouple, dip tube — all DIY-replaceable. Gas valve replacement goes through a State-authorized installer.