AO Smith ENT-40 ProLine® 40-Gallon Electric Water Heater

The ProLine® Standard Electric water heater is the reliable choice when you are looking to maximize your hot water output and is designed with environmentally-friendly insulation to reduce standby heat loss.

With a 40-gallon tank delivering 4,500 watts, the ENT-40 delivers a first-hour rating of 50 gallons at an Energy Factor of 0.95. The Coregard™ sacrificial anode helps protect the tank from the corrosive effects of water and is accompanied by a 6-year limited tank warranty.


Enhanced Heating Elements

Dual 4500 watt elements for the fastest recovery and reliable operation.

Incoloy stainless steel elements last longer than standard copper elements.

DynaClean™ Diffuser Dip Tube

Helps reduce lime and sediment buildup, maximizes hot water output. Made from long lasting PEX cross-linked polymer.

High Energy Factors

Eco-friendly non-CFC foam insulation, heat traps and specially designed combustion chamber combine to produce a high Energy Factor for maximum savings on operating costs.

CoreGard™ Anode Rod

Our anode rods have a stainless steel core that extends the life of the anode rod allowing superior tank protection far longer than standard anode rods.

How it Works

Cold water enters the water heater through an internal “dip tube” which forces the cold water to the bottom of the tank and pushes hot water out through the outlet connection.

This arrangement provides the most hot water for a given tank size. There are two thermostats on a typical residential water heater. The thermostat at the bottom controls the lower heating element while the top thermostat controls the upper heating element.

Usually, only one heating element is active at a time. Because the lower element sees the cold water first, the lower heating element does most of the work, while the upper heating element is used only when the entire tank is cold.

Because water can corrode the steel tank, we glass line the inside of the tank and install an anode rod to help reduce corrosion.

The temperature and pressure relief valve is a safety device designed to open if the internal temperature or pressure of the tank exceeds certain limits.

Water heaters should be large enough to provide adequate hot water even when temperatures are cold and household demand is greatest.