Mizudo FDG-CS100 vs Mizudo FDG-CS80: which uses less energy?
At the low draw pattern the Mizudo FDG-CS100 and the Mizudo FDG-CS80 use the same energy, 95 therms a year each, on the same federal test. Both are filed as a gas tankless unit, so the comparison holds; what separates them is below. Enter your ZIP to price either one on your own rate.
Side by side
Compared within one class only: models filed as a gas tankless unit at the low draw pattern.
| Figure | Mizudo FDG-CS100 | Mizudo FDG-CS80 |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.81 | 0.81 |
| Energy use per year (therms) | 95 | 95 |
| Max flow (GPM) | 2.5 | 2.1 |
| Installed cost range NLR REMDB | $1,698–$2,632 | $1,698–$2,632 |
| CPSC recall naming it CPSC | none on file | none on file |
DOE CCD · 2026-09-19 NLR REMDB · 2026-04-01 CPSC · 2026-09-24
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 above.
- No CPSC recall on file names either model (list checked 2026-09-24).
- The actual warranty term is printed in each model’s documentation, not in any registry.
Which should you pick?
- Pick the Mizudo FDG-CS100 if you run more fixtures at once: it lists 2.5 GPM against 2.1.
- Neither if you need more than 2.5 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.
Each model on its own
- Mizudo FDG-CS100 95 therms a year
- Mizudo FDG-CS80 95 therms a year