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Start with a common tank-size range or choose any exact size on an individual card. You may compare different capacities when that tradeoff matters; every selected capacity stays clearly labeled. Open any review for noise, dimensions, room-air and electrical facts, warranty, controls, daily-verified seller prices, pros, cons, and source documents.

Manufacturer reviews

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Showing the closest available 50–58 gallon model from each manufacturer.

ManufacturerA. O. Smith
A. O. Smith HPTA-50 heat pump water heater

ENERGY STAR 46 gal / 240 V

A. O. Smith HPTA-50

Choose exact size
Rated storage
46 gal
First hour
65 gal
Input voltage
240 V
UEF
3.68
Noise level (dBA)
45 dBA
Sound evidencemanufacturer operation statement; measurement distance/mode not stated Source for the selected size (opens in a new tab)
Minimum room air
450 ft³; 84 ft³ w/ air exchange
Requirement detailsThe current HPTA Series 210 manual requires at least 450 ft³ without added air exchange. Enclosures from 84–449 ft³ are permitted only with one of the manual's transfer-air arrangements: fully louvered door; upper and lower wall grilles; or upper grille plus a 3/4-in door undercut / at least 18 in² net free opening. Each wall grille must be at least 22 × 6 in or 130 in² net free area. Factory duct adapters are also supported; follow the duct section rather than treating 84 ft³ as an unconditional minimum. Source for the selected size (opens in a new tab)
Dimensions
63 in H × 22 in diameter
Open full review
ManufacturerAriston
Ariston ARIHPWH-50 heat pump water heater

ENERGY STAR 45 gal / 240 V

Ariston ARIHPWH-40-T

Choose exact size
Rated storage
37 gal
First hour
65 gal
Input voltage
240 V
UEF
3.55
Noise level (dBA)
45.0 dBA at 6 ft
Sound evidencethird-party certified test procedure stated by exact-model-set specification This exact-model-set document is hosted by a major plumbing distributor, not on the current Ariston domain. The Ariston-domain non-T Side-Connect document reports 49.1 dBA for different model identifiers and is not substituted for these -T choices. Source for the selected size (opens in a new tab)
Minimum room air
700 ft³; smaller w/ ventilation/ducting
Requirement detailsWithout ducts, a room of at least 700 ft³ needs no added ventilation. Below 700 ft³, the official manual requires a fully louvered door or top-and-bottom louvers; its small-closet arrangement requires an 18 in² / 0.75-in under-door opening plus an exhaust-height louver and exhaust within 12 in of the door. With only inlet or outlet ducting, an 18 in² / 0.75-in under-door opening is required. With both inlet and outlet ducted, the manual permits any room size with no added ventilation. No lower universal numeric volume is stated. Source for the selected size (opens in a new tab)
Dimensions
56 1/2 in H × 22 3/4 in diameter
Open full review
ManufacturerBosch
Bosch GreenTronic 7000 T heat pump water heaters

ENERGY STAR 47 gal / 240 V

Bosch TR7000T-50US

Choose exact size
Rated storage
47 gal
First hour
69 gal
Input voltage
240 V
UEF
3.75
Noise level (dBA)
49 dBA
Sound evidenceENERGY STAR sound_pressure_level; manufacturer family operating-sound claim Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Minimum room air
700 ft³; 84 ft³ w/ louvers
Requirement detailsThe model-specific table sets 700 ft³ for an enclosed, not-fully-ducted room with no transfer opening. A fully louvered door, upper/lower louvers, or upper louver plus undercut door permits 84 ft³. An upper louver or undercut plus one duct, or both inlet and outlet ducted, has 'None' in the manual's minimum-space column. That 'None' is configuration-specific and does not waive clearances or duct rules. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
66 1/2 in H × 21 3/4 in diameter
Open full review
ManufacturerBradford White
Bradford White AeroTherm heat pump water heater

ENERGY STAR 45 gal / 240 V

Bradford White RE2H50S10-1NCTT

Choose exact size
Rated storage
45 gal
First hour
65 gal
Input voltage
240 V
UEF
3.44
Noise level (dBA)
<50 dBA avg.
Sound evidencemanufacturer AeroTherm series operating-sound statement The brochure names the core models but does not separately publish the curated -1NCTT suffix variants. Source for the selected size (opens in a new tab)
Minimum room air
700 ft³; smaller w/ ≥240 in² louvers/ducting
Requirement detailsThe manual says the unit is designed for an indoor space of at least 700 ft³. A smaller room is allowed with a fully louvered door or two louvered sections at the top and bottom of the door/wall; louvers should provide at least 240 in² open airflow area. The official ducting kit is another documented alternative for rooms below 700 ft³ or without louvered doors. No lower universal numeric volume is stated. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
59 3/8 in H × 21 3/4 in diameter
Open full review
ManufacturerGE Profile
GE Profile GeoSpring PH50S10BNY01 heat pump water heater

ENERGY STAR 50 gal / 240 V

GE Profile PH50S10BNY

Choose exact size
Rated storage
50 gal
First hour
75 gal
Input voltage
240 V
UEF
4.5
Noise level (dBA)
41 dBA
Sound evidenceENERGY STAR exact-record sound_pressure_level; NEEA 8.1 manufacturer context Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Minimum room air
700 ft³; smaller w/ ≥240 in² louvers/ducting
Requirement detailsGE requires at least 700 ft³ for the common indoor installation. A smaller room is allowed with a fully louvered door, two louvered sections at the top and bottom, or the GE duct kit. Louvers must provide at least 240 in² / 0.15 m² open area. The manual does not state a lower universal numeric volume. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
68 1/4 in H × 24 in diameter
Open full review
ManufacturerLG
LG APHWC501M heat pump water heater

ENERGY STAR 53 gal / 240 V

LG APHWC501M

Choose exact size
Rated storage
53 gal
First hour
76 gal
Input voltage
240 V
UEF
3.93
Noise level (dBA)
42–45 dBA by mode
Sound evidencemanufacturer dB(A) table by operating mode Source for the selected size (opens in a new tab)
Minimum room air
700 ft³ minimum
Requirement detailsLG's official installation instructions state a 700 ft³ minimum room size. No manufacturer-approved smaller-room louver or duct alternative was found in the reviewed owner/installation manual, so do not imply one. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
63 31/32 in H × 22 27/32 in W × 22 29/32 in D
Open full review
ManufacturerRheem
Rheem PROPH40 T2 RH375-SO heat pump water heater

Official manufacturer details

Rheem PROPH40 T2 RH375-SO

Choose exact size
Rated storage
36 gal
First hour
60 gal
Input voltage
240 V
UEF
3.75
Noise level (dBA)
49 dBA
Sound evidencemanufacturer exact-model table; distance/mode not stated Source for the selected size (opens in a new tab)
Minimum room air
700 ft³; smaller w/ ventilation/ducting
Requirement detailsUnducted rooms above 700 ft³ need no added ventilation. Below 700 ft³ use a fully louvered door or top/bottom louvers; the small-closet arrangement requires an 18 in² / 0.75-in door gap plus an exhaust-height louver and exhaust within 12 in of the door. One-duct layouts require the stated transfer opening; both inlet and outlet ducted permits any-size room with no added ventilation. No lower universal numeric volume is stated. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
62 5/16 in H × 20 1/4 in diameter
Open full review
ManufacturerRinnai
Rinnai REHP80BM heat pump water heater

ENERGY STAR 75 gal / 240 V

Rinnai REHP50

Choose exact size
Rated storage
46 gal
First hour
73 gal
Input voltage
240 V
UEF
3.75
Noise level (dBA)
49 dBA
Sound evidenceENERGY STAR exact-record sound_pressure_level Source for the selected size (opens in a new tab)
Minimum room air
700 ft³; 84–700 ft³ w/ louvers
Requirement detailsThe official 2026 manual says rooms above 700 ft³ need no added ventilation. Unducted rooms larger than 84 ft³ and below 700 ft³ require a fully or double-louvered door with 250 in² total net free area and 5 ft grille separation. It also documents a separate unducted 'room smaller than 450 ft³' arrangement with no numeric minimum, a 24 in² under-door air gap, an exhaust-height louver, and exhaust within 12 in of the door. Fully ducted rooms below 85 ft³ have no stated minimum; partially ducted rooms below 85 ft³ have no stated minimum but require the page-16 transfer-air arrangement. The overlapping 84/85/450 wording is preserved verbatim rather than silently normalized. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
66.4 in H × 21.7 in diameter
Open full review
ManufacturerSANCO2
SANCO2 heat pump and hot water storage tanks

ENERGY STAR 83 gal / 230 V

SANCO2 GS5-45HPC HP + ECO-83SSAQB

Choose exact size
Rated storage
83 gal
First hour
121 gal
Input voltage
230 V
UEF
3.8
Noise level (dBA)
37 dBA outdoor unit
Sound evidenceoutdoor GS5-45HPC sound level, not indoor tank/whole-system sound This is the outdoor heat-pump component value, not a tank-generated or whole-system indoor acoustic measurement. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Minimum room air
N/A — outdoor heat pump
Requirement detailsThe official GS5 manual requires the GS5-45HPC heat-pump unit outdoors; the separate storage tank may be indoors or outdoors. Therefore an integrated-HPWH indoor room-volume minimum does not apply to these systems. Outdoor airflow clearances, an outdoor location, and the manual's maximum tank-to-heat-pump distance still apply. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
68 7/8 in H × 24 1/2 in diameter
Open full review
ManufacturerStiebel Eltron
Stiebel Eltron Accelera heat pump water heaters

Official manufacturer details

Stiebel Eltron Accelera 220 E

Choose exact size
Rated storage
58 gal
First hour
51 gal
Input voltage
208–240V
UEF
3.115
Noise level (dBA)
45–52 dBA @ 1 m
Sound evidencesound pressure at 3.3 ft (1 m) versus sound power; do not compare as one metric The 45 dBA value conflicts with the current 2.2024 technical specification's 52 dBA value at the same stated distance. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Minimum room air
800 ft³ minimum
Requirement detailsThe official Accelera 220 E / 300 E manual says not to install in a room with less than 800 cubic feet total volume. The diagram labels the same example '800 ft2' but immediately gives 10 × 10 × 8 ft and the narrative explicitly says 800 cubic feet; this report follows the unambiguous volume statement. No manufacturer-approved duct/louver exception was found in the reviewed manual. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
60 7/8 in H × 27 1/8 in diameter
Open full review
ManufacturerCala Systems
Cala Systems RDH6524M1 heat pump water heater

ENERGY STAR 65 gal / 240 V

Cala Systems RDH6524M1

Choose exact size
Rated storage
65 gal
First hour
79 gal
Input voltage
240 V
UEF
3.61
Noise level (dBA)
48 / 49–52 dBA
Sound evidenceexact-model manufacturer sources with different test/disclosure context This range conflicts with the 48 dBA qualified internal test in the September 2025 specification. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Minimum room air
700 ft³; smaller w/ louvers/ducting
Requirement detailsCala says ducting is not required if the room is larger than 700 ft³. Below 700 ft³, ducting is also not required with a fully louvered door, top-and-bottom door louvers, or a top louver aligned with and facing the outlet plus at least 20 in² open area under the door. Otherwise the installer must determine an approved duct configuration. No lower universal numeric volume is stated. Source for the selected size (opens in a new tab) Second source for the selected size (opens in a new tab)
Dimensions
67 in H × 24 in diameter
Open full review
How these manufacturers were selected

Different manufacturers were selected for a brand-diverse comparison. Current ENERGY STAR facts are shown where an exact or declared-series catalog binding exists; otherwise the missing catalog match is explicit.

This is a brand-diverse comparison—not a sales ranking, quality score, household-fit result, price claim, or recommendation. Sources reviewed 2026-08-28; refresh required before 2026-08-31.

See the manufacturers in one quick table
One representative heat-pump water-heater model from each featured manufacturer, compared using current ENERGY STAR-listed facts when available
Manufacturer and modelRated storageFirst hourInput voltage120V line optionUEFListed annual use
A. O. Smith
HPTA-50 210		46 gal65 gal240 VYes — separate exact model3.68883 kWh/year
Ariston
ARIHPWH-50		45 gal68 gal240 VN/A3.75867 kWh/year
Bosch
TR7000T – 50US		47 gal69 gal240 VN/A3.75855 kWh/year
Bradford White
RE2H50S10-1NCTT		45 gal65 gal240 VN/A3.44944 kWh/year
GE Profile
PH50S10BNY01		50 gal75 gal240 VYes — separate exact model4.51102 kWh/year
LG
APHWC501M		53 gal76 gal240 VN/A3.931262 kWh/year
Rheem
PROPH40 T2 RH375-SO		N/AN/AN/AYes — separate exact modelN/AN/A
Rinnai
REHP80BM		75 gal91 gal240 VN/A41225 kWh/year
SANCO2
GS5-45HPC HP + ECO-83SSAQB		83 gal121 gal230 VN/A3.81313 kWh/year
Stiebel Eltron
Accelera 220 E		N/AN/AN/AN/AN/AN/A
Cala Systems
RDH6524M1		65 gal79 gal240 VN/A3.61N/A
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  • Certification record

    AMERICAN STANDARD WATER HEATERS ASHPWH-50*****

    ENERGY STAR ID
    2408487
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.75
    Storage volume
    45 gal
    First-hour rating
    68 gal
    Listed annual electric usage
    867 kWh/year

  • Certification record

    AMERICAN STANDARD WATER HEATERS ASHPWH-65*****

    ENERGY STAR ID
    2683732
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.85
    Storage volume
    62 gal
    First-hour rating
    78 gal
    Listed annual electric usage
    1289 kWh/year

  • Certification record

    AMERICAN STANDARD WATER HEATERS ASHPWH-80*****

    ENERGY STAR ID
    2408486
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    4.01
    Storage volume
    73 gal
    First-hour rating
    87 gal
    Listed annual electric usage
    1238 kWh/year

  • Certification record

    Arctic Arctic-HP-Hot Water-KA06-50

    ENERGY STAR ID
    4576901
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.88
    Storage volume
    44.5 gal
    First-hour rating
    65 gal
    Listed annual electric usage
    837 kWh/year

  • Certification record

    Arctic Arctic-HP-Hot Water-KA06-80

    ENERGY STAR ID
    4576902
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    4.14
    Storage volume
    71 gal
    First-hour rating
    81 gal
    Listed annual electric usage
    1199.7 kWh/year

  • Certification record

    Ariston ARIHPWH-40

    ENERGY STAR ID
    3942613
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.58
    Storage volume
    37 gal
    First-hour rating
    66 gal
    Listed annual electric usage
    907 kWh/year

  • Certification record

    Ariston ARIHPWH-40-T

    ENERGY STAR ID
    4518065
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.55
    Storage volume
    37 gal
    First-hour rating
    65 gal
    Listed annual electric usage
    915 kWh/year

  • Certification record

    Ariston ARIHPWH-50

    ENERGY STAR ID
    3942616
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.75
    Storage volume
    45 gal
    First-hour rating
    68 gal
    Listed annual electric usage
    867 kWh/year

  • Certification record

    Ariston ARIHPWH-50-T

    ENERGY STAR ID
    4437414
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.83
    Storage volume
    45 gal
    First-hour rating
    69 gal
    Listed annual electric usage
    848 kWh/year

  • Certification record

    Ariston ARIHPWH-65

    ENERGY STAR ID
    3942614
    Type
    240 Volt Integrated HPWH
    Uniform Energy Factor
    3.85
    Storage volume
    62 gal
    First-hour rating
    78 gal
    Listed annual electric usage
    1289 kWh/year