eyoo EO8K-W vs Mizudo FDG-CS120S: which uses less energy?
At the medium draw pattern the Mizudo FDG-CS120S uses 134 therms a year and the eyoo EO8K-W 135 — 2 therms (1%) less, about 16 therms over ten years. Both are filed as a gas 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 a gas tankless unit at the medium draw pattern.
| Figure | eyoo EO8K-W | Mizudo FDG-CS120S |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.82 | 0.83 (better) |
| Energy use per year (therms) | 135 | 134 (better) |
| Max flow (GPM) | 3.2 | 3.3 |
| Installed cost range | $1,745–$2,687 | $1,792–$2,743 |
| 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 Mizudo FDG-CS120S if running cost matters most: it uses 2 therms less a year on the same test.
- Pick the eyoo EO8K-W if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Mizudo FDG-CS120S.
- Neither if you need more than 3.3 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.
Each model on its own
-
eyoo EO8K-W
Its filed figures, class position and running cost on your ZIP.
-
Mizudo FDG-CS120S
Its filed figures, class position and running cost on your ZIP.