Water heaters
Tank, tankless and heat pump water heaters.
Buyer's guide: Water heaters: heat pump, tankless, or conventional tankWe hold full sourced data on 22 water heaters, each with a specification traced to its source and cross-checked against owner reports.
All the water heaters we have data on
Ranked by what owners report, then efficiency and price. Answer the questions above to rank for your house.
Heat pump water heaters
GE Profile GeoSpring Smart Hybrid
GE's flagship heat pump water heater, relaunched under the Profile line with FlexCAPACITY mixing and Wi-Fi control. ENERGY STAR-certified at UEF 4.50 -- the highest efficiency figure in this catalogue at any size.
Rheem ProTerra Hybrid
The default heat pump water heater for most US households: 50 gallons, UEF 3.75, widely stocked and widely serviced.
Owners: 2 watch-out2 mixed 11 reports across the line →A.O. Smith ProLine XE Voltex AL
66-gallon heat pump water heater with a UEF of 4.02 -- among the highest in our water heater set, just behind GE's Profile GeoSpring Smart Hybrid at 4.50. Sold under A. O. Smith's 'ProLine XE Voltex AL / Smart Hybrid' line — a different, retail-exclusive 'Signature Series' name is used for a different model-number family at Lowe's, so don't cross-shop the names.
Owners: 1 watch-out2 mixed 12 reports across the line →Bradford AeroTherm Series G2
Bradford White's second-generation 50-gallon heat pump water heater pairs a 3.89 UEF with app controls and a 10-year tank warranty. It is sold mainly through plumbing suppliers rather than big-box stores.
Owners: 1 good1 mixed 4 reports across the line →Heat pump water heaters (split system)
A.O. Smith Voltex X
Outdoor CO2 split-system heat pump water heater introduced in August 2026, with a 47-gallon indoor tank and a model-specific UEF of 3.52.
SANCO2
Split-system CO2 refrigerant heat pump water heater rated to operate down to -25°F ambient, with a UEF of 3.75.
Owners: 3 good2 mixed 13 reports across the line →Gas tank water heaters
Bradford Defender Safety System
Bradford White's baseline pro-channel natural-gas tank, atmospheric vent, with the Defender flammable-vapor-resistant (FVIR) burner chamber. UEF 0.63 — confirmed as UEF, not an older Energy Factor rating, on Bradford White's own current spec sheet, though some retailers mislabel the same number 'EF'.
Owners: 1 watch-out1 mixed 6 reports across the line →Rheem Performance Platinum
Rheem's step-up atmospheric natural gas tank: 50 gallons, UEF 0.64, a 77-gallon first-hour rating, and a 12-year tank-and-parts warranty (versus 6 years on Rheem's value-tier Performance gas tank).
Owners: 1 watch-out 13 reports across the line →Rheem Performance Gas
Rheem's baseline atmospheric natural gas tank: 50 gallons, UEF 0.63, an 85-gallon first-hour rating, and a 6-year tank-and-parts warranty.
Electric tank water heaters
Rheem Marathon
Conventional resistance-element electric tank with a lifetime-warranted, non-metallic fiberglass tank — no compressor, no heat pump efficiency, but a tank that structurally can't rust through.
Owners: 1 mixed 4 reports across the line →Rheem Performance Electric
Rheem's baseline resistance-electric tank: 50 gallons ('Medium' height configuration), UEF 0.93, dual 4500W elements, a 61-gallon first-hour rating, and a 6-year tank-and-parts warranty.
Owners: 1 watch-out 5 reports across the line →Gas tankless water heaters
Bradford Infiniti GR
New 150,000 BTU/h Infiniti GR tankless family launched in August 2026 with a built-in recirculation pump and gas or propane configurations.
Navien NPE-A2
Condensing gas tankless water heater, UEF 0.95, 11.2 GPM at a 35°F rise — Navien's mid-large residential model, ENERGY STAR certified.
Owners: 1 watch-out1 mixed 2 reports across the line →Rinnai RX Series
Condensing gas tankless water heater, UEF 0.93, endless hot water with no standby loss.
Owners: 1 good1 watch-out1 mixed 7 reports across the line →Rheem RTG-R
9.5 GPM non-condensing tankless gas water heater introduced in March 2026 with an integrated recirculation pump and EcoNet Wi-Fi.
Rinnai RE Series
Rinnai's non-condensing indoor gas tankless: 8.5 GPM max flow, UEF 0.82, 180,000 BTU/h, a 5-year parts warranty with a separate 15-year heat-exchanger term. Not ENERGY STAR rated.
Electric tankless water heaters
Rheem Performance RETEX
Rheem's 24kW retail electric tankless delivers 4.68 GPM at a 35°F rise, but it needs three 40-amp double-pole breakers. It carries a 5-year heat-exchanger warranty and just 1 year on parts.
Owners: 1 watch-out 15 reports across the line →Stiebel Tempra 24 Plus
Stiebel Eltron's Advanced Flow Control electric tankless: 24kW, UEF 0.93, roughly 4.68 GPM at a 35°F-equivalent rise, a 3-year parts warranty (7-year limited).
Owners: 1 watch-out 11 reports across the line →What the specifications mean
UEF
Uniform Energy Factor -- the DOE-standard measure of water heater efficiency.
Values above 1.0 are only possible for heat pump water heaters, which move heat rather than create it. A UEF of 3.5 means the unit delivers 3.5 units of water heating per unit of electricity.
Tank capacity (gal)
Storage volume.
First hour rating (gal)
Gallons of hot water deliverable in the first hour starting from a full tank.
More useful than raw tank size for judging whether the household runs out of hot water.
Minimum ambient air temperature (°F)
Coldest surrounding air temperature at which a heat pump water heater runs in heat pump mode.
A heat pump water heater in an unconditioned garage in a cold climate spends the winter on resistance backup, which erases its efficiency advantage.
Durability is read from objective signals only — the weakest link in the warranty, the refrigerant's service outlook, and what trade and owner reports say about parts and service. How we research → · Comparing whole system types, not just this category? Run the recommender →