A.O. Smith vs Noritz: Full-Line Tank Brand vs Tankless-Only Manufacturer
A.O. Smith publishes tank, tankless, and hybrid heat pump electric water heaters in one catalog. Noritz publishes gas tankless water heaters exclusively and does not sell tank models in the US. The comparison only applies once tankless has already been chosen.
Updated August 2026
Who wins what
Homeowners still deciding between tank, tankless, and heat pump formats.
Basis: A.O. Smith publishes tank, tankless, and hybrid heat pump electric lines; Noritz publishes gas tankless water heaters exclusively in the US.
Homeowners who have already committed to gas tankless and want a manufacturer with no tank product line to divide its published engineering focus.
Basis: Noritz's entire published US catalog is gas tankless water heaters, with no tank line.
Everyone, since neither publishes installed pricing.
Basis: Neither manufacturer publishes a combined equipment-plus-labor installed price.
Key differences at a glance
Core product focus
A.O. Smith- A.O. Smith
- Full catalog: tank, tankless, and hybrid heat pump electric water heaters
- Noritz
- Gas tankless water heaters exclusively; no published US tank line
Tankless heat exchanger warranty
Even- A.O. Smith
- Published 12-year heat exchanger, 5-year parts on residential condensing tankless models
- Noritz
- Published 12-year heat exchanger, 5-year parts on residential condensing tankless models
Fuel type coverage
A.O. Smith- A.O. Smith
- Gas, electric, and heat pump electric
- Noritz
- Gas only
Distribution
Even- A.O. Smith
- Retail, online, wholesale, and contractor
- Noritz
- Wholesale and contractor, with more limited retail presence than larger tank manufacturers
Full scorecard
| Metric | A.O. Smith | Noritz | Edge |
|---|---|---|---|
| Tank warrantyRow excluded from direct comparison since Noritz has no published tank product | 6 to 12 years by tier, registered | Not applicable; Noritz does not publish a US tank line | Even |
| Parts warrantyManufacturer limited warranty documentation | 5 years on A.O. Smith's residential tankless models | 5 years on Noritz's residential tankless models | Even |
| First-hour rating or flow rateManufacturer spec sheets | Tank models publish first-hour rating (GPH); tankless models publish flow rate (GPM) by model | Flow rate (GPM) published by model and groundwater temperature | Even |
| Fuel typeManufacturer product catalogs | Gas, electric, and heat pump electric | Gas only | A.O. Smith |
Which one is right for you?
Choose A.O. Smith if…
- You want a single manufacturer that publishes tank, tankless, and heat pump electric options, rather than Noritz's tankless-only catalog.
- You need an electric or heat pump water heater, which Noritz does not publish at all.
- You want a standard tank replacement rather than a tankless system.
Choose Noritz if…
- You have already decided on gas tankless and want a manufacturer whose entire published catalog is tankless.
- Your contractor is a certified Noritz installer with established parts access.
- Your published warranty comparison for the specific models quoted is essentially even, and installer familiarity is the deciding factor.
Choose neither if…
- Your gas meter, gas line sizing, and venting run have not yet been evaluated by a licensed contractor for either brand's condensing tankless unit.
- Your current tank is under warranty and the failure traces to a low-cost part, not the tank itself, so neither an A.O. Smith nor a Noritz tankless swap is justified yet.
- You have not compared written quotes for A.O. Smith and Noritz from the same local installer before assuming either brand's price.
The short answer
A.O. Smith publishes tank, tankless, and heat pump water heaters in one catalog. Noritz sells gas tankless water heaters exclusively in the US, with no published tank line. On comparable condensing tankless models, published warranty terms are close. Neither company publishes installed pricing or independent reliability data.
Cost breakdown
| Line item | A.O. Smith | Noritz |
|---|---|---|
| Condensing tankless unit, mid-capacity residential | Listed at some retailers; wholesale pricing also common | Not published by the manufacturer |
| Venting and gas line modification | Set by the contractor; often required for tankless conversions | Set by the contractor; often required for tankless conversions |
| Installation labor | Set by the installer | Set by the installer |
| Permits | Set by your jurisdiction | Set by your jurisdiction |
Neither brand publishes an installed price bundling equipment and labor. A tankless conversion from a tank often requires gas line upsizing or new venting, which a licensed contractor should price as a separate line item from the unit itself.
Decision framework
A.O. Smith publishes all three formats; Noritz publishes gas tankless only.
Noritz does not publish a tank or electric water heater in its US catalog.
Noritz's entire published catalog is gas tankless water heaters.
Between A.O. Smith and Noritz, warranty service is tied to whichever brand your installer is certified to support.
- Assuming Noritz sells any tank or electric water heater; its published US catalog is gas tankless exclusively.
- Comparing A.O. Smith's entry-tier tankless warranty against Noritz's mid-tier model and calling the gap a brand-wide difference.
- Assuming A.O. Smith's or Noritz's tankless unit will slide into your current tank's footprint without a contractor first checking gas line sizing and venting.
- Assuming a retail-listed A.O. Smith price or a Noritz contractor quote already includes venting, gas line work, and old tank disposal.
- Not confirming that a licensed plumber, rather than a general handyman, handles the gas line and venting work for either an A.O. Smith or Noritz tankless swap.
Tools and next steps
Frequently compared next
Frequently asked questions
Does Noritz make tank water heaters?
No. Noritz's published US catalog is gas tankless water heaters exclusively; it does not sell a tank product line in the US market.
Does A.O. Smith make gas tankless water heaters?
Yes. A.O. Smith's published catalog includes residential gas tankless models, including condensing units, alongside its tank and hybrid heat pump electric lines, unlike Noritz's tankless-only lineup.
Which brand has the longer tankless warranty?
Published tankless warranty terms are similar on comparable residential condensing models from both brands, commonly a 12-year heat exchanger and 5-year parts tier. Confirm the exact tier for the model quoted.
Is one brand more reliable than the other?
We found no independent public dataset ranking A.O. Smith against Noritz for reliability or repair frequency, so we do not publish a ranking.
Can I replace an existing tank with either brand's tankless unit without other changes?
Not always. Switching to an A.O. Smith or Noritz tankless unit can require a larger gas line, new venting, or an added electrical circuit; have a licensed contractor assess your home before quoting either brand.
Is gas line or venting work involved in either installation safe to do myself?
No, for either an A.O. Smith or a Noritz tankless conversion. Gas line, venting, and combustion-related work should be evaluated and performed by a licensed plumbing or HVAC contractor in accordance with local plumbing and mechanical codes. Do not attempt gas line, flue, or venting modifications yourself.
Verify these details yourself
- Installed price for either brand in your local market.
- Whether your local contractor stocks both brands or only one.
- Real-world reliability or failure rates; no independent dataset was found.
- Exact warranty terms for the specific model line quoted, which vary within each brand's catalog.
- Whether your existing gas line and venting can support a tankless conversion without upsizing.
Methodology and sources
Specifications, pricing, warranties, and availability may change. We verify key details against official or reputable public sources and note where information is estimated or not publicly disclosed. HomeownerAnswers does not perform product testing.
- A.O. Smith water heater warranty documentation - Official manufacturer, checked 2026-08-03, confidence: high
- Noritz residential tankless warranty documentation - Official manufacturer, checked 2026-08-03, confidence: high
- ENERGY STAR water heater criteria - Government, checked 2026-08-03, confidence: high
- Department of Energy water heater efficiency guidance - Government, checked 2026-08-03, confidence: high
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