Bosch Tronic 4000 C 8
#18 in ElectricFull review
For instant hot water at a kitchen or bathroom sink far from the main heater.
Amazon $229$229
The Bosch Tronic 4000 C 8 is the better tankless water heater overall, rated 2.5 to 2.4. The Rheem RTEX-06T wins on efficiency. The Rheem RTEX-06T costs $40 less ($189 vs $229).
Rheem RTEX-06T
#20 in ElectricFull review
For instant hot water at a single bathroom or kitchen sink on a budget.
Amazon $189$189
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 Rheem RTEX-06T for efficiency (0.94 UEF vs 0.92 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 | Bosch Tronic 4000 C 8 | Rheem RTEX-06T |
|---|---|---|
| Overall rating | 2.5/5 | 2.4/5 |
| Value 35% | 39 $26.94 per kW ($229, 8.5 kW) | 33 $29.08 per kW ($189, 6.5 kW) |
| Heating power 25% | 0 8.5 kW | 0 6.5 kW |
| Efficiency 15% | 25 0.92 UEF | 50 0.94 UEF |
| Warranty 25% | 50 heat exchanger warranty not published (neutral score used) | 29 5-year heat exchanger warranty |
Specifications
| Bosch Tronic 4000 C 8 | Rheem RTEX-06T | |
|---|---|---|
| Heating | ||
| Fuel | Electric | Electric |
| Electric power | 8.5 kW | 6.5 kW |
| Max flow | 1.6 GPM | 1.6 GPM |
| UEF | 0.92 | 0.94 |
| Installation | ||
| Voltage | 240 V | 240 V |
| Breakers | 40 A total | 30 A total |
| Weight | 4.4 lb | 4 lb |
| Features | ||
| Built-in recirculation | No | No |
| Wi-Fi | No | No |
| Heat exchanger warranty | - | 5 years |
| Parts warranty | - | 1 year |
| Released | 2023-01 | - |