Every certified water heater, sorted by what the test measured

The list holds 1,138 model numbers from 69 brands, grouped into 187 distinct rating sets. Filter by type, size and first-hour output, then compare.

Highest UEF among heat-pump sets

Each dot is one rating set, on the measure that matters most for that kind.

Holds 609 model numbers in 101 rating sets

UEF of each set; compare within one draw pattern

Holds 367 model numbers in 40 rating sets

Max flow, gal/min at a 67 °F rise

Holds 134 model numbers in 19 rating sets

First-hour rating, gal

Holds 28 model numbers in 27 rating sets

Collector area, sq ft

88%

of the certified model numbers share every rating with a model sold under another brand name: 1,005 of 1,138.

Each square is one model number; copper squares sit in a multi-brand rating set.

What a first-hour rating tells you
Equal tank sizes, unequal first hours: medians per rated gallon by type.
UEF explained, from 0.86 to 4.50
Why heat pumps and gas units sit on different scales, draw pattern by draw pattern.
Draw patterns, the label behind every UEF
How the test sorts each heater into very small, low, medium or high.
Heat-pump subtypes: 120-volt, 240-volt and split
What the ratings show for each heat-pump type.
Identical ratings, different brand names
How the 1,138 listings reduce to 187 distinct rating sets.
Tankless max flow at a 67 °F rise
Reading the flow figure against gas input.
Compressor cut-off and refrigerants
Where heat-pump compressors stop, and which refrigerants the list uses.