AO Smith ProMax Review

Gas powered direct vent, high efficiency and high recovery ProMax models

Explore the popular models from AO Smith Promax series; direct vent, power vent, high efficiency and high recovery gas-powered water heaters and its advanced features.



Advanced features

FVIR protection system

FVIR or Flammable Vapor Ignition Resistance technology is used to keep the flammable vapors safely inside the gas combustion chamber, where specially designed flame arrestor prevents the flame or sparks leaving the unit.

DynaClean self-cleaning system

DynaClean system is a system that is very benefitial for the water heater, as it reduces the lime and sediment build up; and therefore, allowing the system to keep its efficiency and maximize hot water output.

PermaGlass and CoreGard anti-rust system

PermaGlass and CoreGard are two mechanisms that are designed for durability of water heater tanks and to keep the rust away from the tank. The manufacturer uses the special glass coating on the inner tank surface and the exclusive aluminum anode rod with a stainless steel core.

Eco-friendly gas burner

Green Choice gas burner is the eco-friendly burner as it produces less NOx gases when burning the gas (33% lower emission) than standard type burners.


AO Smith Promax Models

ProMax line of AO Smith water heaters is the biggest and most diverse group from this manufacturer:

ProMax Ultra Low NOx

ao smith water heater ultra low nox

AO Smith ProMax Ultra Low NOx series of gas water heaters is equipped with the improved gas burner, which allow these units to meet strict standards for low NOx emission. As the burner is made of the stainless steel for a longer life and safety, it utilizes a combination of radiant heat and excess air to meet high standards.

There are five ProMax models that are "green" and environment friendly. Natural gas models have the capacity range from 30 to 50 gallons, energy efficiency from 0.58 to 0.62, and gas input 30,000 and 40,000 BTU.

ProMax Plus High Recovery

ao smith water heater promax high recovery

AO Smith ProMax Plus is the group of water heaters with the highest recovery and the first hour ratings. The tank capacity is in a range from 38 to 98 gallons, energy factor from 0.57 to 0.60 and BTU gas input from 50,000 to 75,100. They are the right solution for large families and homes with the high hot water demand.

Comparison: ProMax model FCG-100 has a capacity of 98 gallons and gas input of 75,100 BTU and is able to get recovery rate up to 81 gallons per hour and deliver up to 150 gallons of hot water in the first hour.

Rheem, Fury Heavy Duty, 42V100F model, has a capacity of 98 gallons and gas input of 75,000 BTU, can get recovery up to 75.8 gallons per hour and deliver max. 135 gallons of hot water in the first hour.

All AO Smith ProMax models are designed with Flammable Vapor Ignition Resistant C3 technology except tanks with 74 and 98 gallons capacity. Discover the benefits of C3 Technology, "Eco-friendly" burner and Dynaclean dip tube on 50-gallon high recovery A.O. Smith GCVX-50. Models such as the Promax SL are designed for heating not only a potable water buy space heating as well.


emergency plumber

ProMax Plus High Efficiency

ao smith water heater promax high efficiency

All AO Smith ProMax Plus High Efficiency models, with capacities 30, 40 and 50 gallons, were Energy Star qualified, with the energy factors 0.62 and 0.63 and gas input 35,500 and 40,000 BTU. Since the requirements for the Energy Star approval are changed (EF should be at least 0.67) the above units are not qualified anymore). But they are still high efficient, save on energy and eligible for some rebates.

50-gallon, A.O. Smith GPVH-50, is the pefect example; it is designed with all the powerfull features AO Smith offers; C3 technology, FVIR, Dynaclean diffuser dip tube, Green Choice gas burner, hot surface ignition and has a good 0.65 energy factor.

Specially design heat traps and 2 inch thick foam insulation are making these ProMax Plus units energy efficient, plus reducing NOx emission by 33% due to eco-friendly Green Choice gas burner (compared to the standard burners).

Example: 40 gallons high efficiency water heater has the first-hour rating 71 gallons and 41 recovery rate, while high recovery ProMax models, the same size water heater, has 88 gallons first-hour rating and 48 recovery rate.

ProMax Closed Combustion
Power Direct Vent

For closed combustion water heater operation the outside air has to be delivered in sufficient volume as the indoor air is not enough for proper combustion. This is why these gas models have two-pipe system, one to direct flue gases out and the other to draw the air inside the water heater.

AO Smith ProMax models with the closed combustion and power direct vent are flexible in venting installation; permitting combined horizontal and vertical venting and air intake up to 45 ft or 15 m, using PVC, ABS and CPVC inexpensive pipes.

Since these ProMax units are power direct-vent, they are using a quiet modular blower for this venting operation.

Another great feature is Intelli-Vent gas control with a very hard to break hot surface igniter, advanced electronics for precise water temperature control and simplified diagnostics' system.

Available models are with a capacity of 40, 50 and 75 gallon tanks, 40,000 to 70,000 BTU input per hour and EF from 0.58 to 0.60.

Other models

If among described AO Smith water heaters, you didn't find what are you looking for, look at the ProMax models below for more options:

  • ProMax Power Vent - electrical power needed for flexible venting system.
  • ProMax Direct Vent - one pipe for venting and air intake, no electrical power needed. A.O. Smith GDV-50 is one of the direct vent models that are using one pipe, dual channel closed system. This is a 50-gallon water heater that can vent up to 40 feet that takes the outside air for combustion so no worries about insufficient indoor ventilation.
  • ProMax SL - for recirculating hot water loop systems.
  • ProMax SL Direct Vent - closed combustion two-pipe vent system, no electrical power required.
  • ProMax SL Power Direct Vent - closed combustion two pipe system to draw the air in and vents outside your home.
  • AO Smith ProMax SL Standard Vent.

Related Articles

(All pictures are courtesy of AO Smith)