DoesTheMath

ELIOS MGWH150IXNN vs ThermoMate JSLG44-26VE1(2"): which uses less energy?

At the high draw pattern the ELIOS MGWH150IXNN uses 178 therms a year and the ThermoMate JSLG44-26VE1(2") 184 — 6 therms (3%) less, about 58 therms over ten years. Both are filed as a gas tankless unit, 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 tankless unit at the high draw pattern.

Filed and computed figures
ELIOS MGWH150IXNN ThermoMate JSLG44-26VE1(2")
UEF (Uniform Energy Factor) 0.95 (better) 0.92
Energy use per year (therms) 178 (better) 184
Max flow (GPM) 4.1 4.1
Installed cost range $2,358–$3,405 $2,216–$3,239
ENERGY STAR certified yes not matched
On the market since 2026-01-28 not filed
DOE CCD · 2026-09-19

What it costs to run

ELIOS MGWH150IXNN: 178 therms a year ThermoMate JSLG44-26VE1(2"): 184 therms a year

ELIOS MGWH150IXNN — 178 therms a year ThermoMate JSLG44-26VE1(2") — 184 therms a year

ELIOS MGWH150IXNN is 6 therms a year lower than ThermoMate JSLG44-26VE1(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.
  • The actual warranty term is printed in each model’s documentation, not in any registry.

Which should you pick?

  • Pick the ELIOS MGWH150IXNN if running cost matters most: it uses 6 therms less a year on the same test.
  • Pick the ThermoMate JSLG44-26VE1(2") if the installed price matters more than the running cost: its modeled installed range is $2,216–$3,239 against $2,358–$3,405.
  • Neither if you need more than 4.1 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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