Rheem AM004120T vs Shenzhen Cansirong Trading Co., Ltd RX-021: which uses less energy?
At the very small draw pattern the Shenzhen Cansirong Trading Co., Ltd RX-021 uses 622 kWh a year and the Rheem AM004120T 628 — 7 kWh (1%) less, about 66 kWh over ten years. Both are filed as an electric tankless unit, so the comparison holds. Enter your ZIP below to price the difference.
Side by side
Compared within one class only: models filed as an electric tankless unit at the very small draw pattern.
| Figure | Rheem AM004120T | Shenzhen Cansirong Trading Co., Ltd RX-021 |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.94 | 0.95 (better) |
| Energy use per year (kWh) | 628 | 622 (better) |
| Max flow (GPM) | 0.3 | 0.3 |
| Installed cost range | $1,300–$1,790 | $1,303–$1,814 |
| ENERGY STAR certified | not matched | not matched |
What it costs to run
Reliability
Not published: Reliability, failure rates and each model’s actual warranty term.
The registries these figures come from certify energy performance under a federal test; none of them records how long a unit lasts or how often it fails, so this page does not rank the two on reliability.
What is here instead:
- The filed efficiency, capacity and tank size of both models, side by side below.
- The actual warranty term is printed in each model’s documentation, not in any registry.
Which should you pick?
- Pick the Shenzhen Cansirong Trading Co., Ltd RX-021 if running cost matters most: it uses 7 kWh less a year on the same test.
- Pick the Rheem AM004120T if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Shenzhen Cansirong Trading Co., Ltd RX-021.
- Neither if you need more than 0.3 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.
Each model on its own
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Rheem AM004120T
Its filed figures, class position and running cost on your ZIP.
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Shenzhen Cansirong Trading Co., Ltd RX-021
Its filed figures, class position and running cost on your ZIP.