Both are heat pump water heaters. The NWP500S050AUMB is more efficient (UEF 3.85 vs 3.46). The NWP500S050AUMB saves $17/year to operate. All figures from published specs and EIA energy prices.
Performance
| Spec | NWP500S050AUMB Navien · Heat Pump | NHP50 Noritz · Heat Pump |
|---|---|---|
| UEF | 3.85Difference: 0.39 | 3.46 |
| Capacity | 44 gal | 47 galDifference: 3 gal |
| First Hour Rating | 65 galDifference: 7 gal | 58 gal |
| kW Input | 5 kW | 4.50 kWDifference: 0.50 kW |
The NWP500S050AUMB leads on efficiency. But does it fit? Sizing guide
Physical dimensions
| Dimension | NWP500S050AUMB | NHP50 |
|---|---|---|
| Height | 63" | 58.30"Difference: 4.70" |
| Width | 21.70"Difference: 6.30" | 28" |
| Depth | 21.70"Difference: 6.30" | 28" |
| Weight | 181 lbs | — |
The NWP500S050AUMB is taller. Fit checked. Now the operating cost.
Operating cost
| Cost | NWP500S050AUMB | NHP50 |
|---|---|---|
| Annual Operating Cost | $145/yrDifference: $17/yr | $162/yr |
| 10-Year Operating Cost | $1,450Difference: $170 | $1,620 |
| Annual Energy | 840 kWhDifference: 98 kWh | 938 kWh |
10-year modeled difference is $170. 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 NHP50 ranges from $103/yr (ND) to $390/yr (HI).
$17/yr separates them. Install requirements determine the upfront gap. Installation accessories
Installation requirements
| Requirement | NWP500S050AUMB | NHP50 |
|---|---|---|
| Voltage | 240Videntical | |
| Amperage | 23Aidentical | |
| Breaker | 30Aidentical | |
| Condensate Drain | Yes | — |
Same electrical requirements. Swapping between these units should not require electrical changes.
Warranty
| Coverage | NWP500S050AUMB | NHP50 |
|---|---|---|
| Tank | 10 yridentical | |
| Parts | 10 yr | — |
| Labor | 1 yr | — |
Features
| Feature | NWP500S050AUMB | NHP50 |
|---|---|---|
| Wi-Fi / Smart | Yes | — |
| Noise Level | 45 dBDifference: 9 dB | 54 dB |
| Refrigerant | R-134aidentical | |
Decision split
Pick this one if...
Navien NWP500S050AUMB
- Minimizing energy cost matters (saves $17/yr)
- You need quiet operation (45 dB vs 54 dB)
- You want smart home / Wi-Fi control
- Peak efficiency is the priority (UEF 3.85)
Pick this one if...
Noritz NHP50
- Your ceiling or space is under 63"
Neither if...
- Your home only has 120V service and you cannot upgrade the panel
- Your install space is under 700 sq ft of open air
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