Model specs
NWP500S050AUMB
Navien / 44-Gallon Heat Pump Water Heater
Lower running cost than standard electric, but height, 240V, and condensate still decide fit.
UEF3.85Certified efficiency
First hour65 galHot water delivery
Footprint63" × 21.7"Height × depth
Running cost~$147/yrU.S. average electricity
Estimated annual savings: $467 compared to a standard standard electric tank. Based on U.S. average energy prices. See all heat pump models
NWP500S050AUMB operating cost
This unit saves roughly $467 every year compared to the standard electric tank it replaces
NWP500S050AUMB
$147/yr
Std tank (0.92 UEF)
$613/yr
~2.6year payback
At $467/yr in savings, the upfront premium pays for itself in about 2.6 years. Over 10 years: roughly $3,470 in net savings.
Your state changes the math. Annual cost ranges from ~$92/yr (ND) to ~$334/yr (HI).
U.S. avg electricity: 17.4¢/kWh (EIA, Jan 2026). The federal tax credit of up to $2,000 under IRA Section 25C expired December 31, 2025. State and utility rebates may still apply.
Your state changes the cost. Ranges from $92/yr to $334/yr depending on your state's electricity rate.
NWP500S050AUMB cost by state
Ranges from $92/yr to $334/yr depending on your state's electricity rate. U.S. average: $147/yr.
Alabama$135/yr16.1¢/kWhAlaska$214/yr25.5¢/kWhArizona$131/yr15.6¢/kWhArkansas$104/yr12.3¢/kWhCalifornia$254/yr30.3¢/kWhColorado$138/yr16.4¢/kWhConnecticut$238/yr28.3¢/kWhDelaware$139/yr16.5¢/kWhDistrict of Columbia$199/yr23.7¢/kWhFlorida$134/yr15.9¢/kWhGeorgia$121/yr14.5¢/kWhHawaii$334/yr39.8¢/kWhIdaho$101/yr12.1¢/kWhIllinois$137/yr16.4¢/kWhIndiana$136/yr16.2¢/kWhIowa$108/yr12.8¢/kWhKansas$120/yr14.3¢/kWhKentucky$120/yr14.3¢/kWhLouisiana$105/yr12.5¢/kWhMaine$258/yr30.7¢/kWhMaryland$173/yr20.6¢/kWhMassachusetts$262/yr31.2¢/kWhMichigan$164/yr19.5¢/kWhMinnesota$126/yr15.0¢/kWhMississippi$120/yr14.2¢/kWhMissouri$99/yr11.8¢/kWhMontana$108/yr12.9¢/kWhNebraska$99/yr11.8¢/kWhNevada$117/yr14.0¢/kWhNew Hampshire$221/yr26.3¢/kWhNew Jersey$194/yr23.1¢/kWhNew Mexico$123/yr14.7¢/kWhNew York$238/yr28.4¢/kWhNorth Carolina$115/yr13.7¢/kWhNorth Dakota$92/yr10.9¢/kWhOhio$148/yr17.6¢/kWhOklahoma$106/yr12.6¢/kWhOregon$123/yr14.7¢/kWhPennsylvania$170/yr20.2¢/kWhRhode Island$253/yr30.1¢/kWhSouth Carolina$129/yr15.4¢/kWhSouth Dakota$114/yr13.6¢/kWhTennessee$110/yr13.1¢/kWhTexas$132/yr15.7¢/kWhUtah$108/yr12.9¢/kWhVermont$196/yr23.3¢/kWhVirginia$133/yr15.9¢/kWhWashington$116/yr13.8¢/kWhWest Virginia$124/yr14.8¢/kWhWisconsin$153/yr18.2¢/kWhWyoming$108/yr12.8¢/kWh
Based on 840 kWh/yr (ENERGY STAR rated) at each state's residential electricity rate (EIA, Jan 2026). Click a state for rebates, code requirements, and model rankings.
NWP500S050AUMB in the 50-gallon heat pump class: #3 of 8 on efficiency.
Should this be on your shortlist?
Best for
shallowest footprint, lightest unit in class, 10-year tank warranty (class-leading)
- Why it makes shortlists: top-half efficiency in a 8-model class
Shortlist alternatives in 50-gallon heat pump:
Bradford White RE2HP50-1NCTTUEF 3.89 · 46.1" tallRheem PROPH50 T2 RH400-30UEF 3.88 · 61.8" tallA. O. Smith HPTS-50-2UEF 3.8 · 63" tallWithin Navien's 50-gallon heat pump lineup, this page fills a specific role.
Where it sits in the Navien lineup
- On efficiency, Navien NWP500S080AUMB sits higher in Navien's 50-gallon heat pump lineup at 4.05 UEF versus 3.85 here.
- For heavier simultaneous demand, Navien NWP500S080AUMB is higher at 85 first-hour gallons versus 65 here.
- Fit is strongest where height is tight: this is the shortest published option in Navien's 50-gallon heat pump lineup at 63 inches.
The bill may work. Now check what actually changes on install day before you let the shortlist settle.
Switching to the NWP500S050AUMB
From a standard electric tank
Same voltage (240V). Verify breaker size matches unit requirements (30A typical).
Taller unit (63"). Measure overhead clearance.
Condensate drain needed. Floor drain or condensate pump.
Air space needed around the unit for heat exchange.
Fewest install changes of any upgrade path. Scope depends on existing wiring, clearances, and condensate routing.
From a gas tank
New 240V/30A circuit required. Hire an electrician.
Gas line capped. No more gas bill for hot water.
Existing flue/vent can be removed.
Condensate drain needed.
Two trades needed (plumber + electrician).
From an older heat pump
Same electrical. Same condensate drain.
Check height. This unit is 63" tall.
Standard water connections.
Similar installation profile. Verify dimensions, clearances, and condensate routing match your existing setup.
Height, electrical service, condensate, and noise. These are the four things that determine whether a heat pump fits your space and your quote.
NWP500S050AUMB installation specifications
Dimensions
Height63 in
Width21.7 in
Depth21.7 in
Weight181 lbs
Connections3/4 inch NPT
Electrical
Voltage240V
Amperage23A
Breaker30A dedicated
Heat Pump
Min ambient temp41°F
Max ambient temp113°F
RefrigerantR-134a
Noise45 dBA
Safety and installation warnings
These warnings apply to this water heater type. Always follow the manufacturer's installation instructions and local building codes. Hire a licensed professional for installation.
T&P relief valve. Every tank-type water heater has a temperature and pressure relief (T&P) valve. This is a critical safety device that prevents tank rupture by releasing water if temperature exceeds 210°F or pressure exceeds 150 PSI. The discharge pipe must run to within 6 inches of the floor or to an exterior drain. Never cap or plug the T&P valve. Test it annually.
Scald prevention. The recommended maximum water temperature is 120°F to prevent scalding. Higher temperatures (130-140°F) reduce Legionella bacteria risk but require a thermostatic mixing valve at the outlet to deliver safe temperatures at fixtures. Some jurisdictions require mixing valves when the tank is set above 120°F.
Cold-climate performance. Below 41°F ambient air temperature, the heat pump compressor shuts off and the unit falls back to electric resistance heating at much lower efficiency. The rated UEF assumes DOE test conditions (67°F ambient, 58°F inlet water). In cold climates or unconditioned spaces (garages, unfinished basements), actual annual efficiency will be lower than the rated UEF, and energy costs will be higher than the estimates shown above.
Cold exhaust air. Heat pump water heaters extract heat from surrounding air and exhaust cold, dehumidified air. Do not install in a space that is already difficult to heat. The unit will lower the room temperature by several degrees, which may increase HVAC costs or reduce heat pump efficiency in winter.
Common install considerations for heat pump units
What is required depends on your existing installation, local code, and installer preference.
Warranty
Coverage
Tank10 yr
Parts10 yr
Labor1 yr
Class rankings: 50-gallon heat pump water heaters
Rankings
Efficiency (UEF) higher is better
#3Top TierEfficiency · 8 models tested
1
Bradford White RE2HP...
2
Rheem PROPH50 T2 RH4...
3
Navien NWP500S050AUMB
4
A. O. Smith HPTS-50-2
5
Rinnai REHP50BM
6
A. O. Smith HPTA-50-2
7
Noritz NHP50
8
Bradford White RE2H50S
Height shortest to tallest
#5of 8Compactness
1
Bradford White RE2HP...
2
Noritz NHP50
3
Bradford White RE2H50S
4
Rheem PROPH50 T2 RH4...
5
A. O. Smith HPTA-50-2
6
A. O. Smith HPTS-50-2
7
Navien NWP500S050AUMB
8
Rinnai REHP50BM
First Hour Rating higher means more hot water
#3Top TierHot Water Delivery · 8 models tested
1
Rinnai REHP50BM
2
Rheem PROPH50 T2 RH4...
3
A. O. Smith HPTA-50-2
4
A. O. Smith HPTS-50-2
5
Bradford White RE2H50S
6
Bradford White RE2HP...
7
Navien NWP500S050AUMB
8
Noritz NHP50
Starting May 2029, new federal standards require heat pump technology for electric water heaters over 35 gallons. Electric tanks 35 gal and under can still use resistance elements. Every heat pump on this list already exceeds the future standard. Read the full DOE 2029 analysis
Common questions about the Navien NWP500S050AUMB
From manufacturer specs, EIA energy data, and DOE regulations.
How much does the NWP500S050AUMB cost to run per year?
~$147/yr at the U.S. average electricity rate. That is roughly $467/yr less than a standard electric tank.
How much hot water does the NWP500S050AUMB deliver?
65 gallons in the first hour from a 44-gallon tank. Suitable for a household of 1 to 3 people at medium draw.
Will the NWP500S050AUMB fit in my space?
63" tall, 21.7" wide, 21.7" deep. Measure your space including clearances before ordering.
What electrical circuit does the NWP500S050AUMB need?
240V, 30A dedicated circuit. Check your electrical panel before installation.
Does the NWP500S050AUMB work in cold climates?
The heat pump operates down to 41°F ambient temperature. Below that, it switches to standard electric resistance mode, losing the efficiency advantage. In cold climates, install inside the heated building envelope, not in an unheated garage.
What warranty does the NWP500S050AUMB come with?
10-year tank warranty, 10-year parts. Register with Navien after installation to activate full coverage.
Is the NWP500S050AUMB eligible for rebates?
ENERGY STAR certified heat pump water heater. The federal tax credit (IRA Section 25C, up to $2,000) expired December 31, 2025. State and utility rebates may still apply depending on your location.
Is this unit future-proof under the 2029 DOE standards?
Yes. Starting May 2029, electric water heaters over 35 gallons must use heat pump technology. This unit already exceeds that standard.
Full specifications
| Performance | |
| UEF | 3.85 |
|---|---|
| First Hour Rating | 65 gal |
| kW Input | 5 kW |
| Draw Pattern | Medium |
| Est. Annual Energy | 840 kWh/yr |
| Capacity | |
| Storage Volume | 44 gal |
| Physical | |
| Height | 63 in |
| Width | 21.7 in |
| Depth | 21.7 in |
| Weight | 181 lbs |
| Connections | 3/4 inch NPT |
| Electrical | |
| Voltage | 240 V |
| Amperage | 23 A |
| Breaker | 30A dedicated |
| Heat Pump | |
| Type | 240 Volt Integrated HPWH |
| Min Ambient | 41 °F |
| Max Ambient | 113 °F |
| Refrigerant | R-134a |
| Sound Level | 45 dBA |
| Warranty | |
| Tank | 10 yr |
| Parts | 10 yr |
| Labor | 1 yr |
| Certifications | |
| ENERGY STAR | Certified |
| Markets | United States, Canada |
Keep the route moving
Other Navien models and the full heat pump guide, if this one isn't the right fit.
- NPE-210S2 5.3 GPM condensing tankless
- NPE-240S2 5.8 GPM condensing tankless
- NWP500S065AUMB 61-gal heat pump
- NWP500S080AUMB 74-gal heat pump
Sources. ENERGY STAR, Navien, Retailer listing. Specs last verified 2026-03-17.Methodology
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