AO Smith Voltex
Hybrid Water Heaters
Review and Buying Tips

Check out how hybrid technology, found in AO Smith Voltex water heaters, delivers excellent benefits and lots of savings to the homeowners - including water heating, cooling, and dehumidifying the surrounding air. This article reviews the positives and negatives found in the Voltex heat pumps from the AO Smith manufacturer.

What makes the AO Smith heat pump better

The Voltex series is a group of hybrid water heaters that utilize both electric technology and heat pump integrated into the top of the tank. The heat pump technology is used as the primary source for high-efficient water heating, while the set of two electric heating elements is utilized as the backup and for faster hot water recovery. Models from the HPTU series, for example, are dual voltage capable, so they can operate using 208 and 240 volts.

Hybrid water heating is what makes AO Smith Voltex ultra-efficient, while the increased storage enables plenty of hot water when demand is high. Such design brings the operating costs down, which is over 70% in energy savings.

The major difference between AO Smith and its competitors is that Voltex is built in three sizes (most others have only one) and utilizes storage tanks with a higher capacity than main competitors: GeoSpring from GE and Rheem.

AO Smith electric heat pumps are available in tank sizes of 50, 66, and 80 gallons, serving on average to large houses with up to 3 showers used simultaneously. Users can enjoy a maximum shower time of up to 55 min, with a maximum energy factor of 3.45, making the unit very efficient and Energy Star approved.

According to the manufacturer, Voltex provides savings of approximately $350 per annum or $3500 during the provided warranty of 10 years.

Models review

Heat pumps are coming from the Proline XE series, which is promoted as "BEST". There are six models total – three HPTU models with the 10-year warranty and three FPTU models with the 6-year warranty:

  • HPTU-50N – 50-gal model
  • HPTU-66N – 66-gal model
  • HPTU-80N – 80-gal model
  • FPTU-50 – 50-gal model
  • FPTU-66 – 66-gal model
  • FPTU-80 – 80-gal model

All the hybrids utilize an advanced electronic user interface with a large LCD display, status icons, touch-buttons, safety lock features, and diode indicators. You can even connect your hybrid water heater to the home management applications via the communication port.

Great flexibility

AO Smith Voltex comes with four operating modes to maximize efficiency and savings and is used for different hot water demand and climate:

High-Efficiency mode - uses heat pump technology only for water heating and maximum efficiency.

Hybrid mode – a water heater utilizes the heat pump for efficiency and heating elements for faster recovery during the high hot water demand.

Electric mode - this is the mode when only heating elements operate. It is recommended to use electric-power heating during periods of cold weather as the heat pump operates with a minimum efficiency. Backup electric elements consist of the lower and upper 4.5 kW elements, both protected from dry firing.

Vacation mode - is the mode used during the period of absence, such as a vacation. This is when the unit is more inactive than active, which reduces the operating costs to the minimum while protecting it during the cold, freezing days.

AO Smith Voltex is a "green" product; it uses an environment-friendly refrigerant and has high efficient heating - so there is less waste. Heat pumps can provide the same amount of hot water as the traditional tank-type model – and are meant for family sizes of four and up, all that for less money.

Smart technology

AO Smith uses a computerized system that makes the usage more convenient, reliable, and safer.

Using the control panel, push-buttons, and its large LCD display, you will have access to its diagnostics system with error codes, temperature control, mode selection, and other useful features.

You can see the heating element or heat-pump functioning icon, on the LCD display, set the temperature in C or F, also the efficiency status, mode indicator, and the panel lock icon.


Two of the main complaints found in user's reviews about AO Smith Voltex are the noise and high upfront cost. The complaint about the noise was coming from the users whose heat pump was installed either in the closet or attached garage, close to the bedroom. As for the other negative complaints, yes, hybrid units are expensive, but according to the manufacturer and presented savings, it seems that the unit pays for itself in two to four years.


Model/Feature Capacity UEF First Hour Rating (GPH) Warranty Dimensions (Inches)
HPTU-50N 50 3.45 66 10 63x22
HPTU-66N 66 3.45 79 10 61x27
HPTU-80N 80 3.45 86 10 69x27
FPTU-50N 50 3.42 66 6 63x22
FPTU-66N 66 3.35 79 6 61x27
FPTU-80N 80 3.45 84 6 69x27


AO Smith Voltex heat pump is ideal for larger families, where electricity is the only power source. It is more expensive than the electric unit, but it is also more than three times efficient and is usually eligible for all kinds of savings, such as utility company rebates or federal tax breaks. This is the only electric water heater that comes with increased thermal efficiency and Energy Star approval.

It has a similar footprint as the standard models, and the installation is as easy. It can be very beneficial if installed in rooms with higher temperatures (attic, utility room with a furnace, or boiler) as it is cooling and dehumidifying the surrounding air.

If you need help with the installation, contact your local plumber.


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