A. O. SMITH HPTU-66N 1 vs RELIANCE WATER HEATERS HPTV-66 2: which uses less energy?

At the high draw pattern the A. O. SMITH HPTU-66N 1** uses 1,438 kWh a year and the RELIANCE WATER HEATERS HPTV-66 2** 1,550 — 112 kWh (7%) less, about 1,123 kWh over ten years. Both are filed as an electric tank, 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 tank at the high draw pattern.

Filed and computed figures
Figure	A. O. SMITH HPTU-66N 1**	RELIANCE WATER HEATERS HPTV-66 2**
UEF (Uniform Energy Factor)	3.45 (better)	3.2
Energy use per year (kWh)	1,438 (better)	1,550
First hour rating (gal)	79	76
Rated storage volume (gal)	67	68
Installed cost range	$3,703–$4,308	$3,707–$4,067
ENERGY STAR certified	yes	yes
Sound level (dB)	not filed	45
Refrigerant	R-134a, GWP 1430	R-513A, GWP 630
On the market since	2019-04-05	2023-07-10

DOE CCD · 2026-09-19

What it costs to run

A. O. SMITH HPTU-66N 1** — 1,438 kWh a year RELIANCE WATER HEATERS HPTV-66 2** — 1,550 kWh a year

A. O. SMITH HPTU-66N 1** is 112 kWh a year lower than RELIANCE WATER HEATERS HPTV-66 2**.

DOE CCD · 2026-09-19

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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.
Both are ENERGY STAR certified, which requires a manufacturer warranty of at least six years; the actual term for each model is not published.
Time on the market, as filed with ENERGY STAR: the A. O. SMITH HPTU-66N 1** since 2019-04-05, the RELIANCE WATER HEATERS HPTV-66 2** since 2023-07-10. A sale date, not a lifespan.

Which should you pick?

Pick the A. O. SMITH HPTU-66N 1** if running cost matters most: it uses 112 kWh less a year on the same test.
Pick the RELIANCE WATER HEATERS HPTV-66 2** 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 HPTU-66N 1**.
Neither if your household's busiest hour needs more than 79 gallons of hot water — neither lists more. Check whether a 65-gallon heater is enough.

Each model on its own

A. O. SMITH HPTU-66N 1**

Its filed figures, class position and running cost on your ZIP.
RELIANCE WATER HEATERS HPTV-66 2**

Its filed figures, class position and running cost on your ZIP.