EcoSmart ECO 36
#1 in ElectricFull review
For a large home with 300 A service that wants all electric hot water. The lifetime warranty and low price per kilowatt make it a strong value if a pro installs it.
Amazon $699$699
The EcoSmart ECO 36 is the better tankless water heater overall, rated 4.3 to 3.3. The EcoSmart ECO 36 leads on warranty and heating power. The EcoSmart ECOS 27 costs $150 less ($549 vs $699).
EcoSmart ECOS 27
#7 in ElectricFull review
A low cost whole home heater for a two bathroom house in a warm climate. The short warranty is the tradeoff for the price.
Amazon $549$549
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 36 for warranty (limited lifetime heat exchanger warranty vs 5-year heat exchanger warranty) and heating power (36 kW vs 27 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 36 | EcoSmart ECOS 27 |
|---|---|---|
| Overall rating | 4.3/5 | 3.3/5 |
| Value 35% | 64 $19.42 per kW ($699, 36 kW) | 60 $20.33 per kW ($549, 27 kW) |
| Heating power 25% | 100 36 kW | 64 27 kW |
| Efficiency 15% | 50 0.94 UEF | 50 0.94 UEF |
| Warranty 25% | 100 limited lifetime heat exchanger warranty | 29 5-year heat exchanger warranty |
Specifications
| EcoSmart ECO 36 | EcoSmart ECOS 27 | |
|---|---|---|
| Heating | ||
| Fuel | Electric | Electric |
| Electric power | 36 kW | 27 kW |
| Max flow | 8.8 GPM | 6.6 GPM |
| UEF | 0.94 | 0.94 |
| Installation | ||
| Voltage | 240 V | 240 V |
| Breakers | 160 A total | 120 A total |
| Weight | 18.4 lb | 10.9 lb |
| Features | ||
| Built-in recirculation | No | No |
| Wi-Fi | No | No |
| Heat exchanger warranty | Limited lifetime | 5 years |
| Parts warranty | - | 1 year |