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California heat pump guideLocal rates, rebates, and operating costs.Colorado heat pump guideLocal rates, rebates, and operating costs.Massachusetts heat pump guideLocal rates, rebates, and operating costs.Oregon heat pump guideLocal rates, rebates, and operating costs.Washington heat pump guideLocal rates, rebates, and operating costs.DOE 2029 standardsWhat changes in 2029 and which product classes move first.

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A.O. Smith Water HeatersPublished models, product lines, and brand coverage.Bradford White Water HeatersPublished models, product lines, and brand coverage.Navien Water HeatersPublished models, product lines, and brand coverage.Noritz Water HeatersPublished models, product lines, and brand coverage.Rheem Water HeatersPublished models, product lines, and brand coverage.Rinnai Water HeatersPublished models, product lines, and brand coverage.Takagi Water HeatersPublished models, product lines, and brand coverage.
Model specs

NWP500S050AUMB

Navien / 44-Gallon Heat Pump Water Heater
Lower running cost than standard electric, but height, 240V, and condensate still decide fit.
ShortlistRunning costInstall changeFull specs
UEF3.85Certified efficiency
First hour65 galHot water delivery
Footprint63" × 21.7"Height × depth
Running cost~$145/yrU.S. average electricity
Estimated annual savings: $461 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 $461 every year compared to the standard electric tank it replaces
NWP500S050AUMB
$145/yr
Std tank (0.92 UEF)
$606/yr
~2.6year payback
At $461/yr in savings, the upfront premium pays for itself in about 2.6 years. Over 10 years: roughly $3,410 in net savings.
Your state changes the math. Annual cost ranges from ~$93/yr (ND) to ~$350/yr (HI).
U.S. avg electricity: $0.17/kWh (EIA, Dec 2025). The federal tax credit of up to $2,000 under IRA Section 25C expired December 31, 2025. State and utility rebates may still apply.
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" tall
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

Common install considerations for heat pump units

What is required depends on your existing installation, local code, and installer preference.

Thermal Expansion Tank Often required by code Check on Amazon (paid link)
Water Heater Drain Pan Often required by code Check on Amazon (paid link)
Earthquake Straps (Seismic Restraints) Often required by code Check on Amazon (paid link)
Full accessories list

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...
3.89
2
Rheem PROPH50 T2 RH4...
3.88
3
Navien NWP500S050AUMB
3.85
4
A. O. Smith HPTS-50-2
3.8
5
Rinnai REHP50BM
3.75
6
A. O. Smith HPTA-50-2
3.68
7
Noritz NHP50
3.46
8
Bradford White RE2H50S
3.44
Height shortest to tallest
#5of 8Compactness
1
Bradford White RE2HP...
46.1"
2
Noritz NHP50
58.3"
3
Bradford White RE2H50S
59.1875"
4
Rheem PROPH50 T2 RH4...
61.75"
5
A. O. Smith HPTA-50-2
63"
6
A. O. Smith HPTS-50-2
63"
7
Navien NWP500S050AUMB
63"
8
Rinnai REHP50BM
66.4"
First Hour Rating higher means more hot water
#3Top TierHot Water Delivery · 8 models tested
1
Rinnai REHP50BM
73 gal
2
Rheem PROPH50 T2 RH4...
67 gal
3
A. O. Smith HPTA-50-2
65 gal
4
A. O. Smith HPTS-50-2
65 gal
5
Bradford White RE2H50S
65 gal
6
Bradford White RE2HP...
65 gal
7
Navien NWP500S050AUMB
65 gal
8
Noritz NHP50
58 gal
⚡
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?
~$145/yr at the U.S. average electricity rate. That is roughly $461/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
UEF3.85
First Hour Rating65 gal
kW Input5 kW
Draw PatternMedium
Est. Annual Energy840 kWh/yr
Capacity
Storage Volume44 gal
Physical
Height63 in
Width21.7 in
Depth21.7 in
Weight181 lbs
Connections3/4 inch NPT
Electrical
Voltage240 V
Amperage23 A
Breaker30A dedicated
Heat Pump
Type240 Volt Integrated HPWH
Min Ambient41 °F
Max Ambient113 °F
RefrigerantR-134a
Sound Level45 dBA
Warranty
Tank10 yr
Parts10 yr
Labor1 yr
Certifications
ENERGY STARCertified
MarketsUnited States, Canada
Keep the route moving

Other Navien models and the full heat pump guide, if this one isn't the right fit.

Head-to-head comparisons
Heat Pump guideAll Navien modelsSizing guideInstallation accessoriesAll models
Sources. ENERGY STAR, Navien, Retailer listing. Data compiled March 2026.Methodology
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