Two of my wife’s coworkers replaced their tank water heaters within a month of each other last year. One went with the Rheem RTEX-24, the other with the EcoSmart ECO 27. Both are happy, and both paid about the same amount for an electrician. That’s actually the most honest starting point for this comparison: these two units are closer in real-world performance than either brand’s marketing suggests.
The Rheem RTEX-24 (24kW, up to 5.9 GPM, $549) and the EcoSmart ECO 27 (27kW, up to 6.5 GPM, $595 to $619 depending on retailer) are both well-reviewed whole-home electric tankless water heaters, with the ECO 27 offering slightly more flow capacity for a similar or slightly higher price. The right choice mostly comes down to your electrical panel’s available breaker capacity and which brand’s parts and support network you’d rather deal with long term.
Side-by-Side Comparison
| Spec | Rheem RTEX-24 | EcoSmart ECO 27 |
|---|---|---|
| Power | 24 kW | 27 kW |
| Max flow rate | Up to 5.9 GPM | 2.7 to 6.5 GPM (varies by inlet temp) |
| Voltage/Amperage | 240V | 240V, 112.5 Amps |
| Breakers required | 3 x 40 AMP | 3 x 30 AMP |
| Dimensions | 18.25”H x 17.63”W x 3.5”D | 17”H x 17”W x 3.5”D |
| Price (2026) | $549.00 (Amazon) | $595.00 to $619.00 |
| Home Depot rating | 3.9 stars (2,814 reviews) | 4.2 stars (2,067 reviews) |
| Efficiency claim | Not independently certified | Up to 99.8% (per manufacturer) |
The ECO 27 actually needs a lower breaker amperage per circuit (30 amp vs 40 amp) despite having a higher kW rating, which is worth understanding: that’s a function of how EcoSmart distributes the load across its three elements rather than a sign of lower power draw overall. Total amperage draw across both units ends up in a similar range once you account for all three circuits combined.
Flow Rate: The ECO 27 Has an Edge on Paper
The ECO 27’s rated range tops out at 6.5 GPM versus the RTEX-24’s 5.9 GPM, a real but modest difference. Both figures come with the same asterisk: actual flow rate depends heavily on incoming water temperature, and both manufacturers publish their top-end numbers based on warmer climate conditions. In practice, the difference between 5.9 and 6.5 GPM matters more on paper than in daily use for most households, since few homes run enough simultaneous fixtures to hit either ceiling regularly.
Reviews: A Closer Look at the Numbers
Home Depot’s review data shows the ECO 27 slightly ahead at 4.2 stars across 2,067 reviews, compared to 3.9 stars across 2,814 reviews for the Rheem unit on the same platform. That’s a real gap, but it’s also a smaller sample size difference than it first appears, and both units land solidly in “generally well-reviewed” territory rather than showing any major red flag.
Independent review site DIYs.com notes the ECO 27 requires a professional plumber for installation as a listed con, which applies just as much to the Rheem RTEX-24 given its similar electrical demands. Neither unit is a casual DIY project if your panel needs upgrading.
Brand and Support Considerations
Rheem has been manufacturing water heating equipment since 1925 and is currently the largest water heater manufacturer in North America. That scale means widely available replacement parts (heating elements, sensors, control boards) and a large enough installed base that plumbers and electricians are generally familiar with the RTEX line specifically.
EcoSmart is a newer, more tankless-specific brand with a strong reputation in the DIY electric tankless space, and its own certifications claim up to 99.8% energy efficiency. Both brands carry a limited warranty, though the specific terms and length vary, so check current warranty documentation directly from each manufacturer before deciding based on that factor alone.
Which One Should You Actually Buy?
If your priority is buying from the most established, widely serviced brand with the broadest parts ecosystem, the Rheem RTEX-24 is the safer long-term bet, especially if you want to be confident that replacement elements or control boards will still be easy to find in five years.
If your priority is squeezing out slightly more flow rate for a similar price, and you’re comfortable with a newer but well-reviewed brand, the EcoSmart ECO 27 is a reasonable pick, particularly if Home Depot’s review data (4.2 vs 3.9 stars) matters to your decision.
Either way, the electrical prep work is nearly identical: three double-pole breaker circuits, adequate panel capacity, and likely a licensed electrician for the hookup. Don’t let the brand choice distract from confirming your home can actually support either unit before you buy.
For more on what the RTEX-24 specifically requires from your electrical panel, see our electrical requirements guide.
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater - Check Current Price on Amazon
The Bottom Line
The Rheem RTEX-24 and EcoSmart ECO 27 are closely matched units serving the same market: whole-home electric tankless heating for small to mid-size households. The ECO 27 edges ahead slightly on flow rate and Home Depot review scores, while the RTEX-24 wins on brand longevity and parts availability. Either is a defensible choice once your electrical panel is confirmed ready.
Frequently Asked Questions
Which is better, the Rheem RTEX-24 or EcoSmart ECO 27? Both are well-reviewed and similarly priced. The ECO 27 offers slightly higher flow rate (6.5 vs 5.9 GPM) and a higher Home Depot review score, while the RTEX-24 benefits from Rheem’s larger manufacturing scale and parts availability.
Is the EcoSmart ECO 27 more powerful than the Rheem RTEX-24? Yes, by kW rating (27kW vs 24kW), though the practical flow rate difference is modest for most households.
Do both units need the same electrical setup? Both need three double-pole breaker circuits, though the ECO 27 uses 30-amp breakers while the RTEX-24 uses 40-amp breakers per circuit.
Which brand has been around longer? Rheem, founded in 1925, has a much longer manufacturing history and is currently the largest water heater manufacturer in North America.
Is the EcoSmart ECO 27 cheaper than the Rheem RTEX-24? Prices are close and fluctuate by retailer. As of 2026, the ECO 27 runs $595 to $619 depending on where you buy, compared to $549 for the RTEX-24 on Amazon.
Can I install either unit myself? Both require significant electrical work (three double-pole breaker circuits) that most manufacturers and reviewers recommend leaving to a licensed electrician.
Which unit has better reviews? On Home Depot’s platform, the EcoSmart ECO 27 holds a 4.2-star average across 2,067 reviews, compared to 3.9 stars across 2,814 reviews for the Rheem RTEX-24.
Does the EcoSmart ECO 27 work in cold climates? Like the RTEX-24, its flow rate drops as incoming water gets colder. EcoSmart’s published range of 2.7 to 6.5 GPM reflects that variability directly.
Are replacement parts easier to find for one brand over the other? Rheem’s larger market presence generally means wider availability of replacement heating elements and parts, though EcoSmart parts are also readily available through major retailers.
Which one should I choose for a larger household? If flow rate is your main concern and your panel supports it, the EcoSmart ECO 27’s slightly higher GPM ceiling may serve a larger household marginally better, though the difference is modest enough that either unit works for most mid-size homes.
References
- EcoSmart ECO 27 official specifications, ecosmartus.com, accessed July 2026: https://www.ecosmartus.com/product/ecosmart-eco-27
- Home Depot customer review data for both Rheem RTEX-24 and EcoSmart ECO 27 listings, accessed July 2026
- Rheem RTEX-24 official product specifications, Amazon.com, accessed July 2026: https://www.amazon.com/dp/B01MS9DVEE