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
2.9/5
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.
- 18 kWHeating power
- 4.4 GPMMax flow
- 0.96UEF
- 5 yearsHeat exchanger warranty
Check price at Amazon$449
Price checked October 31, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Runs a shower and a sink at once in warm climates
- Only two breakers, so it fits panels that cannot take three more
- Light enough for one person to hang
Cons
- Only a 5 year leak warranty and 1 year on parts
- Not enough for a whole home where inlet water is cold
The EcoSmart ECOS family
Every EcoSmart ECOS model we rank, smallest first. Ratings compare each against its own fuel.
| Model | Heating power | Rating | Price |
|---|---|---|---|
| EcoSmart ECOS 18 (this one) | 18 kW | 2.9/5 | $449 |
| EcoSmart ECOS 27 | 27 kW | 3.3/5 | $549 |
How it scores
The rating comes from 4 measured or published factors, each scored 0-100 against fixed reference points for its fuel. How we rank explains each one.
Specifications
| Model number | ECOS 18 |
|---|---|
| Heating | |
| Fuel | Electric |
| Electric power | 18 kW |
| Max flow | 4.4 GPM |
| UEF | 0.96 |
| Installation | |
| Voltage | 240 V |
| Breakers | 80 A total |
| Weight | 9.3 lb |
| Features | |
| Built-in recirculation | No |
| Wi-Fi | No |
| Heat exchanger warranty | 5 years |
| Parts warranty | 1 year |
Alternatives in this fuel
Camplux TEW18
#13 in ElectricFull review
A budget whole home heater for a small home in a warm climate. Buyers who want published flow and efficiency figures should pay more for a Stiebel or EcoSmart.
Amazon $278.95$278.95
Bosch Tronic 4000 C 10
#15 in ElectricFull review
For a busy kitchen sink or a pair of sinks that need more flow than a small point of use heater gives.
Amazon $251.99$251.99
Compare
Compare the EcoSmart ECOS 18 with any other tankless water heater →
More from EcoSmart: every EcoSmart product ranked.