Last updated: July 2026
Picking a water heater brand feels like it shouldn’t be this complicated. But when you’re staring at a $900–$1,800 purchase decision — something that’ll run every day for the next 8–12 years — getting it right matters. Rheem and A.O. Smith are the two biggest names in residential water heaters, and I’ve seen both perform well and fail spectacularly depending on the model and installation.
Here’s the honest breakdown. No brand loyalty, no fluff — just what you actually need to know.
Rheem vs. A.O. Smith: The Quick Verdict
| Category | Rheem | A.O. Smith |
|---|---|---|
| Price range (50-gal tank) | $600–$1,100 | $700–$1,200 |
| Warranty (residential) | 6–12 years | 6–12 years |
| Availability | Home Depot exclusive | Lowe’s, plumbing supply |
| EF/UEF rating | 0.93–0.95 (standard) | 0.92–0.95 (standard) |
| Smart/connected models | Yes (EcoNet) | Yes (iCOMM) |
| Installer preference | Very common | Slightly preferred by pros |
| Parts availability | Excellent | Excellent |
Bottom line up front: Both brands make reliable water heaters at similar price points. A.O. Smith has a slight edge in build quality on upper-tier models. Rheem wins on retail accessibility and mid-range value. Your installer’s familiarity with one brand often matters more than the brand itself.
Brand History: Who Actually Makes These
Rheem has been around since 1925, headquartered in Atlanta. What most homeowners don’t know: Rheem also manufactures Ruud — the contractor-grade brand plumbers install. Same factory, same core components, different label.
A.O. Smith has been making water heaters since 1936, based in Milwaukee. They produce water heaters under brand names including State, American, Reliance, Whirlpool, and Kenmore. If you have one of those brands, it’s likely an A.O. Smith under the hood.
Both companies have enormous manufacturing scale and parts networks. Neither brand will leave you stranded for replacement parts.
Want to see how water heater costs break down overall? Check out our complete water heater installation cost guide for detailed pricing by type and size.
Tank Water Heaters: Head-to-Head Comparison
This is where most homeowners are shopping — a standard 40–80 gallon gas or electric tank unit. Here’s how the two brands compare on models you’ll actually find at the store.
Mid-Range: Rheem Performance vs. A.O. Smith Signature Series
Rheem Performance Series (50 gal, gas):
- Price: $650–$750 at Home Depot
- First Hour Rating (FHR): ~89 gallons
- Warranty: 6-year tank, 1-year parts
- UEF: 0.59
A.O. Smith Signature Series (50 gal, gas):
- Price: $680–$780 at Lowe’s
- First Hour Rating (FHR): ~88 gallons
- Warranty: 6-year tank, 1-year parts
- UEF: 0.60
At this tier, they’re nearly identical. The specs are within margin of error. Your decision should come down to which store is more convenient and who your plumber prefers to install.
Premium Models: Rheem Prestige vs. A.O. Smith ProLine Master
Rheem Prestige Series (50 gal, gas):
- Price: $950–$1,100
- Warranty: 12-year tank, 3-year parts
- Self-cleaning system (dip tube design)
- EcoNet smart connectivity
- UEF: 0.70
A.O. Smith ProLine Master (50 gal, gas):
- Price: $1,000–$1,200
- Warranty: 12-year tank, 3-year parts
- Dynaclean diffuser dip tube
- iCOMM smart connectivity
- UEF: 0.70
At the premium level, A.O. Smith’s build quality is marginally better — the glass lining on their tanks is thicker and the anode rod design is more effective at preventing corrosion long-term. That said, Rheem’s 12-year warranty is equally solid and their EcoNet smart home integration is more user-friendly in practice.
Weighing whether the premium upgrade is worth it? Our breakdown of water heater replacement costs explains what drives the price differences.
Tankless Water Heaters: A.O. Smith’s Edge
Both brands have serious tankless lineups, and this is where they diverge more meaningfully.
Rheem RTGH-95DVLN (9.5 GPM):
- Price: $1,100–$1,300
- UEF: 0.93
- Warranty: 5-year parts, 12-year heat exchanger
- EcoNet compatible
A.O. Smith Signature 700 (9.5 GPM):
- Price: $1,200–$1,400
- UEF: 0.95
- Warranty: 5-year parts, 15-year heat exchanger
- Built-in scale detection
- Better cold-climate performance
For tankless units, A.O. Smith’s 15-year heat exchanger warranty vs. Rheem’s 12-year is a meaningful difference. The heat exchanger is the most expensive component to replace — that extra 3 years of coverage is real money. In hard water areas especially, A.O. Smith is the lean here.
Curious whether tankless is worth the investment? Our guide on whether a tankless water heater saves money runs the real numbers.
Heat Pump Water Heaters: Federal Tax Credits Apply to Both
Heat pump water heaters (HPWHs) are the biggest financial opportunity for homeowners right now. The federal tax credit under the Inflation Reduction Act covers 30% of the purchase and installation cost — up to $2,000 — for qualifying heat pump water heaters. Both Rheem and A.O. Smith have ENERGY STAR certified models that qualify.
Rheem ProTerra Hybrid (50 gal):
- Price: $1,300–$1,500 before tax credit
- UEF: 3.75
- EcoNet smart connectivity
- Estimated annual operating cost: ~$165
A.O. Smith Voltex Hybrid (50 gal):
- Price: $1,350–$1,550 before tax credit
- UEF: 3.70
- Built-in leak detection
- Estimated annual operating cost: ~$170
Both are excellent units. The Rheem ProTerra has a slight efficiency edge. The A.O. Smith Voltex’s built-in leak detection is genuinely useful. After the tax credit, either unit typically pays for itself in energy savings within 3–5 years compared to a standard electric resistance heater.
For the full picture on available credits and rebates, see our guide to heat pump water heater tax credits in 2026.
Warranty Comparison
| Model Tier | Rheem Warranty | A.O. Smith Warranty |
|---|---|---|
| Entry-level tank | 6-yr tank / 1-yr parts | 6-yr tank / 1-yr parts |
| Mid-range tank | 9-yr tank / 2-yr parts | 9-yr tank / 2-yr parts |
| Premium tank | 12-yr tank / 3-yr parts | 12-yr tank / 3-yr parts |
| Tankless — parts | 5 years | 5 years |
| Tankless — heat exchanger | 12 years | 15 years |
| Heat pump | 10-yr tank / 10-yr parts | 10-yr tank / 10-yr parts |
One important note on both brands: warranty registration matters. Some extended warranty periods require registration within 30 days of installation. Your plumber should handle this — confirm it. An unregistered unit may only have base 6-year coverage even if you bought a 12-year model.
What Plumbers Actually Think
Here’s what installers say about both brands — the honest version.
On Rheem: Most commonly available. Easy to get parts same-day at Home Depot. Entry-level models had issues with the plastic pilot assembly in gas units (2019–2022 era) — the newer models have addressed this. EcoNet app is solid but occasionally has connectivity glitches.
On A.O. Smith: Plumbing supply houses tend to stock them, which means faster delivery for contractor-grade units. The anode rod is more accessible for maintenance. Historically slightly fewer warranty claims on the anode rod side. Some contractors find A.O. Smith easier to troubleshoot because of consistent component placement across their model lines.
The difference between a good and bad water heater outcome is almost always installation quality, not brand.
Which One Should You Buy?
Buy Rheem if:
- You’re buying retail at Home Depot
- You want the widest selection of heat pump models
- Budget is tight and you want the best mid-range value
Buy A.O. Smith if:
- You’re going tankless and want the longer heat exchanger warranty
- Your plumber sources from a plumbing supply house
- You’re in hard water territory
- You want built-in leak detection on a heat pump unit
If you need help sizing your unit, our water heater sizing guide walks through the calculation step by step.
Frequently Asked Questions
Is Rheem or A.O. Smith more reliable?
Statistically, they’re very similar in reliability at the same price tier. Differences between model tiers matter more than brand differences.
Why is A.O. Smith more expensive?
At equivalent tiers, A.O. Smith runs $50–$150 more than Rheem. You’re getting slightly better internal components and a longer heat exchanger warranty on tankless models. For most homeowners in the tank segment, the premium isn’t necessary.
Does Rheem make A.O. Smith?
No — they’re separate companies. Rheem makes Ruud. A.O. Smith makes State, American, Reliance, and others.
Which brand is better for hard water?
A.O. Smith’s anode rod design is slightly more effective in hard water. But in very hard water (above 120 mg/L hardness), a water softener matters more than brand choice.
Can I get federal tax credits on either brand?
Yes — both Rheem and A.O. Smith make ENERGY STAR certified heat pump water heaters that qualify for the 30% IRA tax credit (up to $2,000). Confirm ENERGY STAR certification before purchasing.
Get a Free Quote from a Local Plumber
Whichever brand you choose, installation quality matters as much as the unit itself. A typical water heater replacement runs $900–$1,800 for a standard 50-gallon tank unit — parts, labor, permits, and disposal included. Know what you should be paying before you commit.
