A. O. SMITH GUC-30 4** vs RELIANCE WATER HEATERS FMDV-30 2**: which uses less energy?
At the medium draw pattern the RELIANCE WATER HEATERS FMDV-30 2** uses 182 therms a year and the A. O. SMITH GUC-30 4** 188 — 6 therms (3%) less, about 62 therms over ten years. Both are filed as a gas tank, 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 tank at the medium draw pattern.
| Figure | A. O. SMITH GUC-30 4** | RELIANCE WATER HEATERS FMDV-30 2** |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.59 | 0.61 (better) |
| Energy use per year (therms) | 188 | 182 (better) |
| First hour rating (gal) | 62 | 60 |
| Rated storage volume (gal) | 29 | 29 |
| Installed cost range | not published | not published |
| 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 RELIANCE WATER HEATERS FMDV-30 2** if running cost matters most: it uses 6 therms less a year on the same test.
- Pick the A. O. SMITH GUC-30 4** if you need more hot water in your busiest hour: it lists a first hour rating of 62 gallons against 60.
- Neither if your household's busiest hour needs more than 62 gallons of hot water — neither lists more. Check whether a 30-gallon heater is enough.
Each model on its own
-
A. O. SMITH GUC-30 4**
Its filed figures, class position and running cost on your ZIP.
-
RELIANCE WATER HEATERS FMDV-30 2**
Its filed figures, class position and running cost on your ZIP.