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
The EcoSmart ECOS 27 is the better tankless water heater overall, rated 3.3 to 3.0. The EcoSmart ECOS 27 leads on value, heating power and efficiency.
Rheem RTEX-24
#12 in ElectricFull review
A mainstream whole home heater for a two bathroom house in a warm climate. The Stiebel Tempra 24 Trend costs about the same with a longer warranty.
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 ECOS 27 for value ($20.33 per kW ($549, 27 kW) vs $22.88 per kW ($549, 24 kW)), heating power (27 kW vs 24 kW) and efficiency (0.94 UEF vs 0.93 UEF).
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 ECOS 27 | Rheem RTEX-24 |
|---|---|---|
| Overall rating | 3.3/5 | 3.0/5 |
| Value 35% | 60 $20.33 per kW ($549, 27 kW) | 51 $22.88 per kW ($549, 24 kW) |
| Heating power 25% | 64 27 kW | 52 24 kW |
| Efficiency 15% | 50 0.94 UEF | 38 0.93 UEF |
| Warranty 25% | 29 5-year heat exchanger warranty | 29 5-year heat exchanger warranty |
Specifications
| EcoSmart ECOS 27 | Rheem RTEX-24 | |
|---|---|---|
| Heating | ||
| Fuel | Electric | Electric |
| Electric power | 27 kW | 24 kW |
| Max flow | 6.6 GPM | 5.9 GPM |
| UEF | 0.94 | 0.93 |
| Installation | ||
| Voltage | 240 V | 240 V |
| Breakers | 120 A total | 120 A total |
| Weight | 10.9 lb | - |
| Features | ||
| Built-in recirculation | No | No |
| Wi-Fi | No | No |
| Heat exchanger warranty | 5 years | 5 years |
| Parts warranty | 1 year | 1 year |