EcoSmart ECO 11
#5 in ElectricFull review
For a single shower or a pair of sinks in a warm climate, with a lifetime warranty if a pro installs it.
Amazon $244.78$244.78
The EcoSmart ECO 11 is the better tankless water heater overall, rated 3.4 to 2.9. The EcoSmart ECO 11 leads on warranty and value. The EcoSmart ECOS 18 wins on efficiency and heating power. The EcoSmart ECO 11 costs $204.22 less ($244.78 vs $449).
EcoSmart ECOS 18
#14 in ElectricFull review
For a small home or apartment in a warm climate that wants whole house hot water on two breakers. Amazon stock was low when checked.
Amazon $449$449
Prices were last checked October 31, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Which should you buy?
- Choose the EcoSmart ECO 11 for warranty (limited lifetime heat exchanger warranty vs 5-year heat exchanger warranty) and value ($18.83 per kW ($244.78, 13 kW) vs $24.94 per kW ($449, 18 kW)).
- Choose the EcoSmart ECOS 18 for efficiency (0.96 UEF vs 0.92 UEF) and heating power (18 kW vs 13 kW).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every electric tankless water heater; a clear win is highlighted. How we rank explains each one.
| Factor weight | EcoSmart ECO 11 | EcoSmart ECOS 18 |
|---|---|---|
| Overall rating | 3.4/5 | 2.9/5 |
| Value 35% | 66 $18.83 per kW ($244.78, 13 kW) | 45 $24.94 per kW ($449, 18 kW) |
| Heating power 25% | 8 13 kW | 28 18 kW |
| Efficiency 15% | 25 0.92 UEF | 75 0.96 UEF |
| Warranty 25% | 100 limited lifetime heat exchanger warranty | 29 5-year heat exchanger warranty |
Specifications
| EcoSmart ECO 11 | EcoSmart ECOS 18 | |
|---|---|---|
| Heating | ||
| Fuel | Electric | Electric |
| Electric power | 13 kW | 18 kW |
| Max flow | 3.2 GPM | 4.4 GPM |
| UEF | 0.92 | 0.96 |
| Installation | ||
| Voltage | 240 V | 240 V |
| Breakers | 60 A total | 80 A total |
| Weight | 6.5 lb | 9.3 lb |
| Features | ||
| Built-in recirculation | No | No |
| Wi-Fi | No | No |
| Heat exchanger warranty | Limited lifetime | 5 years |
| Parts warranty | - | 1 year |