AO Smith residential water heater warranties run from 6 years on commodity ProMax and Signature 100 models to 10 years on the ProLine Master and Voltex hybrid heat pump line, and 15-year heat exchanger warranty on the ProLine Tankless. Knowing your tier, registration status, and how to file a claim saves real money — warranty parts on AO Smith run $80–$320 per part.
Quick warranty lookup
You need the model number and serial number from the data plate. Both are visible without disassembly — photograph the sticker before calling. Then:
- Online lookup: visit hotwater.com / register-your-product (AO Smith's warranty portal) — enter serial number and get coverage status
- Phone lookup: 1-800-527-1953 (AO Smith residential water heater customer service)
- Through your installer: if Lowe's installed it or an AO Smith-network plumber, they should have the registration on file
Warranty terms by AO Smith tier
| Tier | Tank warranty | Parts warranty |
|---|---|---|
| ProLine Master (plumber channel) | 10 years | 10 years |
| Voltex Hybrid HP | 10 years | 10 years (incl. compressor) |
| Signature Premier (Lowe's flagship) | 9 years | 9 years |
| Vertex (Power Direct Vent) | 8 years | 6 years |
| ProLine | 6 years (9-year upgrade available) | 6 years |
| ProMax / Signature 100 | 6 years | 6 years |
| ProLine Tankless | 15-year heat exchanger | 5 years |
| Cyclone Xi commercial | 3 years | 1 year |
Registering a new AO Smith water heater
AO Smith warranty activation requires registration within 90 days of installation. Unregistered units default to a 6-year baseline that supersedes the tier warranty. A Signature Premier 9-year warranty becomes a 6-year warranty if you skip registration. Register at hotwater.com/register or have your installer do it.
Filing an AO Smith warranty claim
- Confirm coverage via online lookup or phone
- Identify the failed part — photograph the part and the unit's data plate
- Call AO Smith: 1-800-527-1953 with serial number ready
- Receive RMA / part replacement authorization within 1–3 business days
- Schedule labor — labor is your responsibility on residential AO Smith warranties (parts only)
- Install replacement within 30 days; document with photo
Tank-shell failure
If the tank shell fails (rust streaks on base, persistent shell leak), AO Smith ships a complete replacement unit through a distributor. You pay labor and disposal ($400–$900); AO Smith covers the new unit.
Bottom line
AO Smith warranties are competitive when registered. The Coregard anode + Hydrojet on Signature Premier helps real-world tank longevity exceed the 9-year warranty period. Register within 90 days. For troubleshooting before deciding to file a claim, see our troubleshooting hub. For the contractor-channel ProLine Master 10-year warranty, see the ProLine Master line hub.