A. O. Smith Voltex Review
Three 66-gallon heat pump water heaters wearing nearly the same name. The differences are an anode, a valve and about half a UEF point.
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Verdict: buy the Voltex AL for running cost, the Voltex MAX for delivery, and the ProLine XE only if the water is soft. The AL publishes 4.02 UEF and an 82-gallon first-hour rating, and is NEEA Tier 4 qualified. The MAX publishes 3.84 UEF and 83 gallons first hour, runs at 45 dBA, and adds a smart valve A. O. Smith rates at up to 40% more hot water. The ProLine XE is the same 66 gallons at 3.42 UEF and a 6-year anode rating instead of the Voltex line's heavy-duty rod.
A. O. Smith sells three 66-gallon hybrid electric water heaters whose names differ by one word, and retail listings do a poor job of explaining what you give up as the price falls. This page is the comparison the product pages do not make.
The three units, side by side
| Voltex AL (HPTS-66) | Voltex MAX (HPTA-66) | ProLine XE Voltex | |
|---|---|---|---|
| Nominal capacity | 66 gallons | 66 gallons (68 gal rated storage) | 66 gallons |
| Efficiency | 4.02 UEF | 3.84 UEF | 3.42 UEF |
| First-hour rating | 82 gallons | 83 gallons | 79 gallons |
| NEEA qualification | Tier 4 | Tier 3 | Not published |
| Elements | Not published | Dual 4,500 W copper | Not published |
| Electrical | Not published | 208 – 240 V, 23.6 A | Not published |
| Noise | Not published | 45 dBA | Not published |
| Leak protection | Detection, with optional automatic shutoff | Smart Leak Protection with alerts; optional automatic cold-water shutoff valve | Not published |
| Anode | Heavy-duty smart anode, adapts to local water; rated 10 years | Stainless steel CoreGard rod | Heavy-duty, rated 6 years |
| Extra delivery feature | None | Hot Water+, three levels, up to 40% more hot water | None |
| Connectivity | iCOMM with app and display | iCOMM with app | Not published |
| Dimensions | Not published | 64.5 in H x 26.5 in dia | Not published |
| Warranty | 10-year limited | 10-year limited tank and parts | Not published |
| Certification | ENERGY STAR | ENERGY STAR | ENERGY STAR |
The blank cells are deliberate. A. O. Smith publishes a full data sheet for the MAX and a much thinner one for the AL and the ProLine XE, and we do not fill a gap with a figure borrowed from a sibling model. Where a row says Not published, assume nothing and ask the supplier. How we pick.
Voltex AL: the efficiency pick
4.02 UEF is the highest published figure of any water heater in this registry, heat pump or otherwise. Against an electric resistance tank at 0.93 UEF, that is roughly a quarter of the electricity for the same hot water — not a better number, a different order of running cost. A. O. Smith advertises annual savings of up to $607 against a standard electric model, which is a marketing figure built on assumed rates rather than a specification, so treat the UEF as the fact and the dollars as the brochure.
Two things make the AL more interesting than the headline. The first is its NEEA Tier 4 qualification, which is the Northern Climate Specification tier — the same tier the Rheem ProTerra meets, and the credential that speaks to whether the compressor keeps working rather than handing over to the resistance element when the garage gets cold. A. O. Smith does not publish a numeric ambient operating range for the AL the way Rheem does for the ProTerra, so the tier is the strongest cold-climate evidence available for it.
The second is the anode. The AL's heavy-duty rod is rated to protect the tank for ten years and A. O. Smith describes it as adapting to local water conditions. Anode life is what decides when a tank leaks, so a ten-year rating is a durability claim with teeth — and it is precisely what the cheaper ProLine XE gives up.
Voltex MAX: the delivery pick
An 83-gallon first-hour rating from 66 gallons of storage is the largest delivery figure on this page, and it beats the 78 gallons of a conventional 80-gallon electric resistance tank while using a fraction of the electricity. The mechanism is Hot Water+, a smart valve with three settings that A. O. Smith rates at up to 40% more hot water — in plain terms, it stores hotter and blends down, which is the same trick a thermostatic mixing valve performs manually on an ordinary tank, done in the appliance.
The MAX is also the only unit here with a published noise figure: 45 dBA. That is a genuinely useful number in a category where the complaint that arrives in week two is almost always the fan and the compressor, and where almost nobody publishes anything. It does not make the unit silent — a storage tank makes no noise at all, and that is the comparison your household will actually make — but it is evidence where the rest of the market offers adjectives. Heat pump water heater noise covers placement and the four fixes that work.
The trade against the AL is efficiency: 3.84 UEF versus 4.02, and NEEA Tier 3 rather than Tier 4. You are buying delivery and a quieter published number at the cost of some running cost and some cold-climate credential.
ProLine XE Voltex: the price pick, with a condition
Same 66 gallons, a 79-gallon first-hour rating, 3.42 UEF — still roughly three and a half times a resistance tank — for less money. On paper the step down looks like half a UEF point. It is not. It is the anode.
The ProLine XE's heavy-duty anode is rated to protect the tank for six years against the Voltex line's ten. In neutral or soft water that is a reasonable saving. In hard water, and especially in softened water — which is more aggressive toward a sacrificial anode, not less — six years is the figure that comes back as a leaking tank in year eight. If your water is hard, softened, or from a private well, the AL's ten-year anode is the cheaper appliance over its life. Best water heaters for hard water and best water heaters for well water.
The three Voltex units in full
Pick 1 — Highest published heat pump efficiency
A. O. Smith Voltex AL, 66 gal
The efficiency leader on this page at 4.02 UEF, in the capacity that suits a five- or six-person household, with a heavy-duty anode rated to protect the tank for 10 years.
| Capacity | 66 gallons |
|---|---|
| Efficiency | 4.02 UEF |
| First-hour rating | 82 gallons |
| Cold-climate rating | NEEA Northern Climate Specification Tier 4 qualified |
| Anode | Heavy-duty smart anode, adapts to local water conditions; rated to protect the tank for 10 years |
| Connectivity | iCOMM smart connectivity with app and display |
| Leak protection | Leak detection, with an optional automatic water shutoff |
| Warranty | 10-year limited |
| Certification | ENERGY STAR certified |
What is good
- 4.02 UEF is the highest figure of any unit in this registry, and an 82-gallon first-hour rating with it
- 66 gallons removes the recovery anxiety that a 50-gallon heat pump creates in a big household
- The 10-year anode is a real durability claim, not a marketing one
- ENERGY STAR certification keeps it inside most utility rebate lists
What is not
- 66 gallons is a tall, wide cabinet — measure the space before you order
- Sold mainly through wholesale, so availability is slower than big-box
- No numeric ambient operating range is published, so cold-garage suitability rests on the NEEA Tier 4 qualification rather than on a stated lower limit
Skip it if: Skip it if your install space is a closet. A 66-gallon heat pump needs air volume to work, and starving a heat pump water heater of air is how you end up running on the backup element and paying resistance rates for a premium appliance.
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Specifications above from Auer Steel listing, A. O. Smith HPTS-66 Voltex AL; A. O. Smith Voltex AL introduction; First Supply listing, A. O. Smith HPTS-66 Voltex AL. We have not tested this unit ourselves.
Pick 2 — Largest first-hour rating
A. O. Smith Voltex MAX, 66 gal
An 83-gallon first-hour rating at a 3.84 UEF — the heat pump water heater for a household that runs several showers back to back and still wants the running cost of a heat pump.
| Capacity | 66 gallons nominal, 68 gallons rated storage |
|---|---|
| First-hour rating | 83 gallons |
| Efficiency | 3.84 UEF |
| Cold-climate rating | NEEA Northern Climate Specification Tier 3 qualified |
| Elements | Dual 4,500 W copper |
| Electrical | 208 - 240 V, 23.6 A |
| Noise | 45 dBA |
| Dimensions | 64.5 in H x 26.5 in diameter |
| Delivery feature | Hot Water+ smart valve, three levels, rated up to 40% more hot water |
| Leak protection | Smart Leak Protection detection and alerts; optional automatic cold-water shutoff valve |
| Tank protection | Blue Diamond glass lining, stainless CoreGard anode, DynaClean sediment cleaning |
| Warranty | 10-year limited tank and 10-year limited parts |
| Certification | ENERGY STAR certified |
What is good
- 83 gallons in the first hour beats an 80-gallon resistance tank
- 3.84 UEF is still roughly four times a resistance tank
- 66 gallons of storage plus fast recovery is the combination big households actually need
- ENERGY STAR certified for rebate eligibility
What is not
- Lower UEF than the Voltex AL at the same capacity — you are trading some efficiency for delivery
- Large footprint
- Wholesale distribution
Skip it if: Skip it if two people live in the house. You would be buying 66 gallons and an 83-gallon first-hour rating to serve a demand a 50-gallon unit covers, and paying standby losses on the difference every day for a decade.
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Specifications above from First Supply listing, A. O. Smith HPTA-66 Voltex MAX; A. O. Smith product page, Voltex MAX HPTA-66. We have not tested this unit ourselves.
Pick 3 — Cheapest route into a large heat pump
A. O. Smith ProLine XE, 66 gal
The entry point into 66-gallon heat pump capacity: 3.42 UEF and a 79-gallon first-hour rating, with a 6-year anode instead of the Voltex line's 10.
| Capacity | 66 gallons |
|---|---|
| First-hour rating | 79 gallons |
| Efficiency | 3.42 UEF |
| Anode | Heavy-duty, rated to protect the tank for 6 years |
| Certification | ENERGY STAR certified |
What is good
- 79-gallon first-hour rating for the lowest price of the three 66-gallon units here
- 3.42 UEF is still a step change from any resistance tank
- ENERGY STAR certified
- Same large capacity as the Voltex models
What is not
- The 6-year anode rating is the clearest difference from the Voltex line, and anodes are what tanks die from
- Lowest UEF of the heat pump units listed here
- Wholesale distribution
Skip it if: Skip it if your water is hard or softened. Anode life is what decides when the tank leaks, and in aggressive water the 6-year anode rating is the figure that will come back to bite you — pay for the Voltex AL's 10-year anode instead.
No live price feed on this site, so we show none. #ad
Specifications above from First Supply listing, A. O. Smith FPTU-66 ProLine XE Voltex. We have not tested this unit ourselves.
What all three share
Everything that makes a heat pump water heater a different appliance from the tank it replaces applies equally to all three, and none of it is a brand difference:
- Air volume. Roughly 700 cubic feet, or louvered doors on a closet. Starve one and it runs on the resistance element, which means paying premium money for resistance running costs.
- A condensate drain, continuously, not occasionally.
- Headroom. The MAX is 64.5 inches tall and 26.5 inches in diameter — wider than a resistance tank of similar capacity. Measure the alcove before you order, because 66-gallon heat pump cabinets are what most replacement spaces cannot take.
- It cools the room it stands in. Useful in a humid garage, a direct loss in a basement you heat.
- Slow recovery by design, which is exactly why 66 gallons of storage exists in this line rather than 50.
The full advantage-and-disadvantage ledger is at heat pump water heater pros and cons.
Who the Voltex line suits
- A five- or six-person all-electric household with a garage, unfinished basement or real utility space. This is the capacity the line exists for.
- Anyone whose deciding factor is running cost, where 4.02 UEF on the AL is the best published figure available.
- Anyone who needs an 80-gallon tank's delivery without an 80-gallon tank's bill, which is the MAX's whole argument.
- Anyone buying through a plumbing supplier anyway, since this line goes mainly through wholesale rather than big-box retail.
- Hard-water households willing to pay for the ten-year anode, which is the AL.
Who should buy something else
- Anyone replacing a 50-gallon tank in its existing alcove. A 66-gallon heat pump cabinet frequently will not fit. A 50-gallon Rheem ProTerra will.
- Anyone installing in an unheated garage in a cold-winter state. The AL's Tier 4 qualification is good evidence, but Rheem publishes an actual 37 to 145°F ambient range, and a number beats a tier. Rheem ProTerra vs A. O. Smith Voltex.
- A two-person household. You would be buying 66 gallons and paying standby losses on the difference every day for a decade. Water heater size for a family of 2.
- Anyone whose only install location is a heated room they occupy. The unit will steal heat your furnace then replaces, and the efficiency you paid for leaves through the same wall.
- Anyone with no 240 V capacity. A 120 V plug-in model is the version of this appliance you can actually install. Best 120V plug-in heat pump water heaters.
- Anyone with working natural gas and a sound flue. The comparison then is against gas rather than against resistance, and it is a much narrower argument about local fuel prices. Gas vs electric water heaters.
What goes in with it
A water heater is a system, not a box. These are the parts that go in with it, and the ones people discover they need halfway through the job.
- Drain pan
A heat pump water heater makes condensate continuously, so this one is not optional.
- Leak detector
A condensate line that blocks will overflow long before you notice it.
- Expansion tank
Same closed-system rule as any other storage tank.
What we did and did not do
We read A. O. Smith's own product documentation for the Voltex MAX, distributor and ENERGY STAR listings for the AL and the ProLine XE, and compared the published figures against the competing units in this registry. Where A. O. Smith publishes nothing for a model we left the cell blank rather than borrowing a sibling model's number. We have not installed, run or measured any of these units. How we pick.