A. O. SMITH ACTH-199M-(N,P) 1** vs VESTA VHP-199: which uses less energy?
At the high draw pattern the A. O. SMITH ACTH-199M-(N,P) 1** and the VESTA VHP-199 use the same energy, 178 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 high draw pattern.
| Figure | A. O. SMITH ACTH-199M-(N,P) 1** | VESTA VHP-199 |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.95 | 0.95 |
| Energy use per year (therms) | 178 | 178 |
| Max flow (GPM) | 5.8 | 5.7 |
| Installed cost range | $2,358–$3,405 | $2,358–$3,405 |
| ENERGY STAR certified | yes | not matched |
| On the market since | 2026-06-16 | not filed |
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 A. O. SMITH ACTH-199M-(N,P) 1** if its price or availability suits you — on energy the two are level.
- Pick the VESTA VHP-199 if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the A. O. SMITH ACTH-199M-(N,P) 1**.
- Neither if you need more than 5.8 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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A. O. SMITH ACTH-199M-(N,P) 1**
Its filed figures, class position and running cost on your ZIP.
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VESTA VHP-199
Its filed figures, class position and running cost on your ZIP.