DoesTheMath

AMERICAN GCFL-40 1** vs Rheem PROG40S-36N RH67 PV: which uses less energy?

At the medium draw pattern the AMERICAN GCFL-40 1** uses 168 therms a year and the Rheem PROG40S-36N RH67 PV 171 — 3 therms (2%) less, about 26 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.

Filed and computed figures
Figure AMERICAN GCFL-40 1** Rheem PROG40S-36N RH67 PV
UEF (Uniform Energy Factor) 0.66 (better) 0.65
Energy use per year (therms) 168 (better) 171
First hour rating (gal) 65 66
Rated storage volume (gal) 38 39
Installed cost range $1,760–$3,064 $1,716–$2,950
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

AMERICAN GCFL-40 1**: 168 therms a year Rheem PROG40S-36N RH67 PV: 171 therms a year

AMERICAN GCFL-40 1** — 168 therms a year Rheem PROG40S-36N RH67 PV — 171 therms a year

AMERICAN GCFL-40 1** is 3 therms a year lower than Rheem PROG40S-36N RH67 PV.

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.
  • The actual warranty term is printed in each model’s documentation, not in any registry.

Which should you pick?

  • Pick the AMERICAN GCFL-40 1** if running cost matters most: it uses 3 therms less a year on the same test.
  • Pick the Rheem PROG40S-36N RH67 PV if you need more hot water in your busiest hour: it lists a first hour rating of 66 gallons against 65.
  • Neither if your household's busiest hour needs more than 66 gallons of hot water — neither lists more. Check whether a 40-gallon heater is enough.

Each model on its own