Two brands account for more than 70 percent of residential water heaters sold in the United States. If you are standing in the aisle at Home Depot or Lowe’s comparing Rheem and AO Smith, you are looking at the two most-installed names in the country. Both have been building water heaters for decades. Both make gas tanks, electric tanks, tankless units, and heat pumps. Neither is a bad product. But they make different tradeoffs on price, efficiency, warranty, and availability, and those differences are real enough to matter for your wallet over the next 10 years. Here is the honest breakdown from someone who has installed hundreds of both.
Rheem vs AO Smith: Brand Overview
Rheem was founded in 1925 in Richmond, California. Today it is one of the largest water heater manufacturers in North America, producing everything from builder-grade 40-gallon tanks to premium WiFi-connected heat pumps. Rheem products are sold primarily through Home Depot, HVAC wholesalers, and contractor supply houses. Their EcoNet smart platform is one of the better app-connected systems in the residential water heater category.
AO Smith was founded in 1874 in Milwaukee, Wisconsin. They started as a steel fabricator and got into water heaters in 1939. By some measures, AO Smith is now the largest water heater manufacturer in the world by volume. Their residential products are sold primarily through Lowe’s, plumbing wholesalers, and contractor accounts. AO Smith has a consistent reputation for reliable build quality and customer service that actually answers the phone.
Both brands sell into the same price tiers. Both have ENERGY STAR certified models. Both have wide parts availability through plumbing supply houses. The differences show up when you get into specific categories.
Model Lineup: What Each Brand Offers
| Category | Rheem Models | AO Smith Models |
|---|---|---|
| 40-gal gas tank | Performance XG40T12DU38U0 (~$600) | ProLine XE GCN-40 (~$550) |
| 50-gal gas tank | Performance Plus XG50T12DU38U0 (~$800) | ProLine XE GCN-50 (~$700) |
| 80-gal gas tank | Performance Plus XG80T12DU38U0 (~$1,200) | ProLine XE GCN-80 (~$1,100) |
| Gas tankless | Performance Plus RTGH-95DVLN 9.5 GPM (~$900) | ProLine XE GNDH-10 10 GPM (~$900) |
| Heat pump hybrid | ProTerra PROPH50 T2 50-gal (~$1,300) | Voltex HPTU-50N 50-gal (~$1,100) |
Both brands also offer contractor-only professional lines not available at retail. Rheem’s Professional Classic and Classic Plus series and AO Smith’s Signature Premier and ProLine Elite series are specified by plumbers and HVAC contractors and carry additional warranty tiers and component upgrades. If your plumber sources from a supply house rather than a big-box store, you may end up with a higher-grade unit than what you see on the shelf.
Key Comparisons: Category by Category
Price Range: Roughly Equal, With AO Smith Slightly Cheaper on Tanks
On standard gas and electric tank models, the price gap between brands is narrow. A 50-gallon gas AO Smith tank at Lowe’s typically runs $50 to $150 less than the equivalent Rheem at Home Depot. That is a real difference but not a decisive one for most buyers.
The gap grows on heat pump units. AO Smith’s Voltex HPTU-50N runs approximately $1,000 to $1,200 at Lowe’s. Rheem’s ProTerra 50-gallon hybrid runs $1,200 to $1,500 at Home Depot. Whether the efficiency difference covers that gap depends on your utility rate and how long you own the unit. Winner: AO Smith on upfront cost.
Energy Efficiency (UEF): Rheem Wins on Gas Tanks
Uniform Energy Factor (UEF) measures how efficiently a water heater converts energy into hot water. Higher is better.
| Type | Rheem UEF | AO Smith UEF | Winner |
|---|---|---|---|
| Gas tank (50 gal) | Up to 0.93 | 0.64 to 0.70 | Rheem |
| Electric tank (50 gal) | 0.92 to 0.95 | 0.92 to 0.95 | Tie |
| Gas tankless | Up to 0.99 | 0.92 to 0.95 | Rheem |
| Heat pump hybrid | 3.75 to 3.8 | 3.45 to 4.0 | Tie (model-dependent) |
The gas tank efficiency gap is meaningful. A Rheem gas tank at 0.93 UEF versus an AO Smith at 0.70 UEF translates to real dollar savings annually, particularly in homes with high hot water demand. Over 10 years, that difference can more than offset any upfront price gap. If you are buying a gas tank unit, Rheem’s efficiency lead is the most important single number in this comparison. Winner: Rheem on gas tank and tankless efficiency.
Warranty: Split by Product Type
| Product Type | Rheem Warranty | AO Smith Warranty |
|---|---|---|
| Gas/electric tank | 6 to 12 years (tank and parts) | 6 to 12 years (tank and parts) |
| Heat pump hybrid | 12 years (tank, parts, compressor) | 10 years (tank and parts) |
| Gas tankless | 5 years (heat exchanger), 1 year parts/labor | 6 to 15 years (heat exchanger), 5 years parts |
On heat pump units, Rheem’s 12-year warranty edges out AO Smith’s 10 years. On tankless, AO Smith’s longer heat exchanger warranty is the better deal since the heat exchanger is the most expensive component to replace. On standard tanks, they are equivalent at most price tiers. Winner: Split. Rheem for heat pumps, AO Smith for tankless.
Availability: Depends Where You Shop
Rheem’s primary retail channel is Home Depot. AO Smith’s primary retail channel is Lowe’s. Both are also available through plumbing wholesalers and contractor supply houses. In rural areas, one chain often has significantly better stock than the other, so check local inventory before committing. Winner: Tie
Smart Home Features: Rheem EcoNet vs AO Smith iCOMM
Rheem’s EcoNet platform connects to their hybrid and select tank models via WiFi. The app shows real-time energy usage, allows remote temperature adjustment, runs vacation mode, and integrates with Alexa and Google Home. AO Smith’s iCOMM WiFi app allows remote control and scheduling but is less polished than EcoNet, though newer AO Smith models have improved significantly. Winner: Rheem
Customer Service Reputation: AO Smith Wins
AO Smith’s reputation for warranty claims processing and technical support is consistently better than Rheem’s. Their technical support line picks up faster and warranty claims get resolved with less back-and-forth. Some contractors report more friction on Rheem warranty claims for premium models. Winner: AO Smith
Installation Complexity: Tie
Both brands are comparable on installation complexity at equivalent product tiers. Neither requires special tools or unusual procedures. Gas line sizing, venting requirements, and electrical needs are all standard. Any licensed plumber familiar with one brand can install the other without a learning curve. Winner: Tie
Best Pick for Each Use Case
Best budget gas tank: AO Smith ProLine XE. Lower upfront cost, solid 6-year warranty, available at Lowe’s. Straightforward replacement for most homes.
Best premium gas tank: Rheem Professional Prestige series (contractor-sourced). The 0.93 UEF gas tank with 12-year warranty and EcoNet connectivity. Worth the premium for large households with high hot water demand planning to stay put for 12-plus years.
Best tankless: Rheem RTGH-95DVLN (9.5 GPM, 0.96 UEF) for mid-range whole-house gas. Solid efficiency rating and wide parts availability. AO Smith GNDH-10 is a worthy alternative if your plumber has a preferred supplier relationship with their wholesaler.
Best heat pump hybrid: AO Smith Voltex HPTU-50N if budget is the priority (roughly $200 less than Rheem with competitive UEF). Rheem ProTerra PROPH50 T2 if you want the longer 12-year warranty and EcoNet integration. Either qualifies for the federal 30 percent tax credit up to $2,000 under IRA Section 25C.
Real Cost Comparison: Purchase, Installation, and 10-Year Operating Cost
| Scenario | Rheem | AO Smith |
|---|---|---|
| 50-gal gas tank (unit + install) | $1,300 to $2,200 | $1,200 to $2,000 |
| 50-gal gas tank (10-yr energy) | ~$2,500 at 0.93 UEF | ~$3,350 at 0.70 UEF |
| 50-gal gas tank 10-yr total | ~$3,800 to $4,700 | ~$4,550 to $5,350 |
| Heat pump hybrid (unit + install) | $2,200 to $3,000 | $2,000 to $2,700 |
| Heat pump 10-yr energy cost | ~$900 to $1,200 | ~$900 to $1,200 |
| Heat pump 10-yr total (after $2K credit) | ~$1,100 to $2,200 | ~$900 to $1,900 |
The gas tank 10-year math is where Rheem’s efficiency advantage becomes most concrete. Even though the AO Smith tank costs less upfront, the lower UEF means you are burning more gas every day for 10 years. Rheem’s higher efficiency can save $600 to $850 in energy costs over a decade, which more than covers the upfront price difference on most models.
For heat pump units, the energy costs are close enough that price difference and warranty become the deciding factors. The federal tax credit applies to both brands equally. For state rebates that stack on top, see our guide to state water heater rebates for 2026. For the full federal credit breakdown, see our water heater tax credits guide.
For the full tank versus tankless economic comparison, see our tankless vs tank water heater cost comparison. For regional installation cost data, see our water heater installation costs by state guide.
Frequently Asked Questions
Is Rheem or AO Smith more reliable?
Both brands are reliable at comparable price tiers. AO Smith has a slightly better long-term reliability reputation based on installer feedback, particularly for gas tank models. Rheem reliability is strong on premium models but more variable on builder-grade units. Buy the 12-year warranty version of either brand and you are well covered.
Where can I buy Rheem and AO Smith water heaters?
Rheem is the primary brand at Home Depot. AO Smith is the primary brand at Lowe’s. Both brands also sell professional-grade models through plumbing wholesalers like Ferguson, which are not available at big-box stores. If your plumber is sourcing from a supply house, ask specifically whether they are getting the retail or the professional line.
Which brand qualifies for the federal tax credit in 2026?
Both brands have qualifying models. Heat pump water heaters from Rheem and AO Smith that are ENERGY STAR certified qualify for the 30 percent federal tax credit up to $2,000 under IRA Section 25C. Gas tankless models with a UEF of 0.95 or higher qualify for up to $600. Standard gas and electric tank models do not qualify. For state-level incentives that stack on top, see our heat pump water heater rebates by state guide.
Can I install a Rheem or AO Smith water heater myself?
A like-for-like electric tank replacement is legally DIY in some jurisdictions. Gas water heater installation requires a licensed plumber in most states, and pulling a permit is required almost everywhere for gas work. Heat pump units require both a licensed plumber and proper electrical work. Do not skip the permit. An unpermitted installation voids your manufacturer warranty and creates insurance complications if water damage occurs.
How long do Rheem and AO Smith water heaters last?
Standard gas and electric tank models from both brands last 8 to 12 years in typical use. Rheem premium gas tanks can run 12 to 15 years. AO Smith tanks average 10 to 12 years. Heat pump units from both brands are designed for 15 or more years. Tankless units from either brand can last 20 years with annual descaling maintenance.
Does water hardness affect which brand to choose?
Yes. In hard water areas above 11 grains per gallon, both brands benefit from a water softener or dedicated scale protection. Neither brand has a clear edge here. Ask your plumber about powered anode rods, which both brands support on their premium lines. Annual sediment flushing is non-negotiable regardless of brand.
Get Installation Quotes from Licensed Local Plumbers
The installed cost of any water heater depends on your home’s existing gas line size, venting setup, and electrical configuration. A quote based on the unit price alone will almost always be wrong. Get two or three quotes from licensed local plumbers who can assess your specific situation before you commit to a brand or model.
Use the form at the top of this page to connect with licensed plumbers in your area. They can tell you whether your current infrastructure needs upgrades, what permits are required in your jurisdiction, and what the installed cost will actually be for your specific home.
