The Navien NWP500SxxAUMB line holds three certified rating sets of 240 V integrated heat-pump water heaters, 3 model numbers sold as Navien, listed by Navien. Rated volume runs from 44 to 74 gal, and the first-hour rating runs from 65 to 85 gal. UEFs compare only within a draw pattern; the two high-draw sets rate UEF from 4.03 to 4.05. Navien NWP500S080AUMB, the set with the most model numbers, rates 0.17 above the median UEF of the 58 high-draw heat-pump sets (3.88).
UEF ranks compare sets of the same draw pattern only.
Navien NWP500SxxAUMB: first-hour rating against rated volume
Navien NWP500SxxAUMBOther heat-pump sets
First-hour rating, gal
Filled: the three sets of Navien NWP500SxxAUMB; open circles: the other 98 heat-pump sets. Dashed lines mark 1× and 1.5× the rated volume; the highest ratio in the line is 1.48×, on Navien NWP500S050AUMB.
Across the sizes
From Navien NWP500S050AUMB to Navien NWP500S080AUMB, rated volume grows by 30 gal and the first-hour rating by 20 gal: 0.67 gal of first-hour output for each added rated gallon.
The sizes test at different draw patterns (two high and one medium), so UEF and annual energy compare only between sizes that share a pattern (why).
Strongest placings, size by size
Measure
Value
Median of the group
Placing
Compared with
UEFNavien NWP500S050AUMB
3.85
3.56
sixth highest of 38
38 medium-draw heat-pump sets
Rated electricity useNavien NWP500S050AUMB
840 kWh/yr
894 kWh/yr
sixth lowest of 38
38 medium-draw heat-pump sets
Compressor cut-offNavien NWP500S065AUMB
41 °F
36.3 °F
seventh highest of 90, three tied
90 heat-pump sets that report one
UEFNavien NWP500S065AUMB
4.03
3.88
17th highest of 58, two tied
58 high-draw heat-pump sets
Compressor cut-offNavien NWP500S080AUMB
41 °F
36.3 °F
seventh highest of 90, three tied
90 heat-pump sets that report one
UEFNavien NWP500S080AUMB
4.05
3.88
14th highest of 58, three tied
58 high-draw heat-pump sets
Model numbers
The line covers 3 model numbers, first certified 2025-04-21 and most recently 2025-04-22.