Last reviewed: September 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards
US residential water heater shipments fell on both fuels through July 2026. Gas storage units were down 2.5% year to date at 2,487,389, and electric storage units down 5.2% at 2,877,192.
Efficiency is regulated by Uniform Energy Factor under 10 CFR 430.32(d), and the minimum is not a single number: it is a formula that varies with tank volume and draw pattern, which is why no simple “minimum UEF” figure exists.
What the shipment data shows
| Residential storage water heaters | 2026 YTD | 2025 YTD | Change |
|---|---|---|---|
| Gas | 2,487,389 | 2,550,303 | -2.5% |
| Electric | 2,877,192 | 3,035,356 | -5.2% |
July itself was mixed, with gas up 5.2% to 333,499 units and electric down 3.9% to 385,594. A decent month inside a declining year, the same pattern visible across space conditioning equipment. See our shipment report.
Electric units outship gas in absolute terms, 2,877,192 against 2,487,389 year to date, but are falling faster.
How efficiency is regulated
Water heaters are rated on Uniform Energy Factor, which replaced the older Energy Factor measure. Under 10 CFR 430.32(d), the minimum UEF for water heaters manufactured before May 6, 2029 is expressed as a formula rather than a constant, in the form of a base value minus a coefficient multiplied by rated storage volume.
The formula also varies by draw pattern, which classifies the unit by how much hot water it delivers in a first-hour rating test: very small, low, medium or high. A 40 gallon gas storage heater and an 80 gallon one face different minimums, and the same tank faces different minimums under different draw patterns.
Because there is not one. Any page giving a single “minimum UEF” figure has silently fixed a product class, a tank size and a draw pattern. The regulation sets a family of formulas, which is more precise but harder to summarise, and that difficulty is why the number gets misreported.
For what the standards require when you replace a unit, see our water heater replacement guide.
Frequently asked questions
Are water heater shipments rising or falling?
Falling. Through July 2026, US residential gas storage water heater shipments were down 2.5% year to date at 2,487,389 units and electric storage down 5.2% at 2,877,192, per the AHRI July 2026 Statistical Release, even though gas shipments rose in the month itself.
What is the minimum efficiency for a water heater?
There is no single figure. Under 10 CFR 430.32(d) the minimum Uniform Energy Factor is a formula that varies with rated storage volume and draw pattern, so a 40 gallon and an 80 gallon unit face different minimums, as do units in different draw pattern classes.
What is Uniform Energy Factor?
UEF is the federal efficiency metric for water heaters, replacing the older Energy Factor. It is measured under a draw pattern reflecting typical hot water use, so units are classified as very small, low, medium or high draw, and minimum requirements differ accordingly.
Do more homes use gas or electric water heaters?
In shipments, electric outsells gas: 2,877,192 electric storage units shipped year to date through July 2026 against 2,487,389 gas. Electric shipments are also declining faster, down 5.2% against 2.5% for gas.
Methodology and limitations
Shipment figures are the AHRI July 2026 Statistical Release, published September 11, 2026, retrieved as a PDF from ahrinet.org. Efficiency requirements are quoted from 10 CFR 430.32(d).
- Shipments measure movement into distribution, not installations, and include channel stocking.
- AHRI covers participating manufacturers, close to but not identical with the whole market.
- We do not reproduce the full UEF formula tables. The regulation is the authority.
- Shipment counts are not the same as installed base. RECS covers installed water heating separately.
Sources
- Air-Conditioning, Heating, and Refrigeration Institute, July 2026 Statistical Release.
- US Department of Energy, 10 CFR 430.32(d), water heater standards.
The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.
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