Both are heat pump water heaters. Efficiency is nearly identical. The NWP500S050AUMB saves $1/year to operate. All figures from published specs and EIA energy prices.
Performance
| Spec | NWP500S050AUMB Navien · Heat Pump | PROPH50 T2 RH400-30 Rheem · Heat Pump |
|---|---|---|
| UEF | 3.85 | 3.88Difference: 0.03 |
| Capacity | 44 gal | 45 galDifference: 1 gal |
| First Hour Rating | 65 gal | 67 galDifference: 2 gal |
| kW Input | 5 kW | 4.50 kWDifference: 0.50 kW |
But does it fit? Sizing guide
Physical dimensions
| Dimension | NWP500S050AUMB | PROPH50 T2 RH400-30 |
|---|---|---|
| Height | 63" | 61.75"Difference: 1.25" |
| Width | 21.70"Difference: 0.55" | 22.25" |
| Depth | 21.70"Difference: 0.80" | 22.50" |
| Weight | 181 lbsDifference: 4 lbs | 185 lbs |
Fit checked. Now the operating cost.
Operating cost
| Cost | NWP500S050AUMB | PROPH50 T2 RH400-30 |
|---|---|---|
| Annual Operating Cost | $145/yrDifference: $1/yr | $146/yr |
| 10-Year Operating Cost | $1,450Difference: $10 | $1,460 |
| Annual Energy | 840 kWhDifference: 6 kWh | 846 kWh |
10-year modeled difference is $10. At this scale, local energy rates, usage patterns, and install costs matter more than the efficiency delta.
Costs vary by state. The NWP500S050AUMB ranges from $93/yr (ND) to $350/yr (HI). The PROPH50 T2 RH400-30 ranges from $93/yr (ND) to $352/yr (HI).
$1/yr separates them. Install requirements determine the upfront gap. Installation accessories
Installation requirements
| Requirement | NWP500S050AUMB | PROPH50 T2 RH400-30 |
|---|---|---|
| Voltage | 240Videntical | |
| Amperage | 23A | 21ADifference: 2A |
| Breaker | 30Aidentical | |
| Condensate Drain | Yesidentical | |
Same electrical requirements. Swapping between these units should not require electrical changes.
Warranty
| Coverage | NWP500S050AUMB | PROPH50 T2 RH400-30 |
|---|---|---|
| Tank | 10 yridentical | |
| Parts | 10 yridentical | |
| Labor | 1 yr | — |
Features
| Feature | NWP500S050AUMB | PROPH50 T2 RH400-30 |
|---|---|---|
| Wi-Fi / Smart | Yesidentical | |
| Noise Level | 45 dB | — |
| Refrigerant | R-134aidentical | |
Common accessories for this type of installation.
Common install considerations for heat pump units
What is required depends on your existing installation, local code, and installer preference.
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Related
Sources. ENERGY STAR, manufacturer spec sheets, EIA average energy prices.Methodology