DoesTheMath

AMERICAN GCBL-40 4** vs Rheem XG40T06EC36U1: which uses less energy?

At the medium draw pattern the Rheem XG40T06EC36U1 uses 191 therms a year and the AMERICAN GCBL-40 4** 194 — 3 therms (2%) less, about 34 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 GCBL-40 4** Rheem XG40T06EC36U1
UEF (Uniform Energy Factor) 0.57 0.58 (better)
Energy use per year (therms) 194 191 (better)
First hour rating (gal) 68 68
Rated storage volume (gal) 38 38
Installed cost range not published $1,293–$1,862
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

AMERICAN GCBL-40 4**: 194 therms a year Rheem XG40T06EC36U1: 191 therms a year

AMERICAN GCBL-40 4** — 194 therms a year Rheem XG40T06EC36U1 — 191 therms a year

Rheem XG40T06EC36U1 is 3 therms a year lower than AMERICAN GCBL-40 4**.

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 Rheem XG40T06EC36U1 if running cost matters most: it uses 3 therms less a year on the same test.
  • Pick the AMERICAN GCBL-40 4** if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Rheem XG40T06EC36U1.
  • Neither if your household's busiest hour needs more than 68 gallons of hot water — neither lists more. Check whether a 40-gallon heater is enough.

Each model on its own