There are three types of electric hot water heaters: traditional tank-type models, heat pump water heaters, and tankless units.
Tank-Type Electric Hot Water Heaters
Traditional electric tank-style hot water heaters are very simple water heating devices. They basically consist of a storage tank that contains two electric heating elements. Models differ, however, in tank capacity, efficiency and recovery rate, and they have different lifespans.
When purchasing an electric tank hot water heater, most families size their water heater on the basis of tank capacity. Although this is important, a more important consideration is its First Hour Rating (FHR). The FHR, which appears on a new water heater’s Energy Guide label, is the amount of hot water that your water heater can produce during one hour of continuous use. The FHR is a function of both the water heater’s capacity and its recovery rate. The recovery rate is dependent on the power of the water heater’s elements, and is the amount of water the heater can heat in one hour. For example one 50 gallon electric water heater could have a FHR of 67 gallons and a less powerful model might only have a FHR of 57 gallons.
Because the heating elements are immersed in the water, nearly all of the electrical energy drawn by the heating elements goes towards the heating of the water. The difference in efficiency ratings of different models, is largely dependent upon the extent of the heat losses through the walls of the tank. These heat losses are, in turn, dependent on the type and thickness of the insulation around the tank. The efficiency of a water heater is expressed as an Energy Factor (EF), which you can find on the water heater’s Energy Guide Label.
Although traditional tank-style electric hot water heaters look the same from the outside, beneath the surface there are important differences. As a general guide, you will find that models with a 9 to 12 year warranty, have larger heating elements, thicker insulation, a more corrosion resistant tank lining and larger anode rods.
Warranty length is, however, of little value, if the manufacturer provides a poor warranty service. Consumer reviews seem to indicate that Bradford White and Rheem/Ruud offer the best warranty service.
Recommended high efficiency electric tank models that you may want to consider, are Rheem’s “Imperial Electric Series”. These models have a 10 year warranty. They have glass-lined tanks with stainless steel elements, and a good FHR. The Self-cleaning Richmond 12E water heaters and the Reliance 1212 models have a 12 year warranty. The Richmond water heater models include a heat trap and a pipe insulation kit to reduce heat losses. Both the Richmond and the Reliance water heater models include several advanced feature that contribute to the longevity of their tanks. The AO Smith “Conservationist” water heaters have a 10 year warranty. They have very efficient, durable heating elements, and a dip tube that prevents sediment build-up.
There are some electric hot water heaters that offer a lifetime warranty against the tank leaking. Rheem’s Marathon water heater cannot leak or rust because it has a plastic tank. The outer shell is a rugged polyethylene jacket that resists wear and tear. The wide gap between the inner tank and the outer jacket, is filled with insulation. This insulation is so effective that the Marathon water heaters have the highest efficiency rating of all electric tank hot water heaters.
Whether or not the high efficiency tank models are economically justifiable is debatable, but they will minimize environmental degradation. If you cannot afford these water heaters, you could reduce the operating costs of a standard tank electric tank water heater by putting an insulation jacket around the tank, and using a water heater timer, so that the water is only heated just prior to peak usage times. You could also insulate your water pipes, and add a heat trap.
Heat Pump Electric Hot Water Heaters
If you are looking for the best electric hot water heater, you should consider purchasing a heat pump water heater. This super-efficient, environmentally friendly water heater, will substantially lower your water heating bills,. Heat pumps have been used in HVAC applications for some time now, but have only recently been utilized for water heating.
A heat pump works like an air conditioner in reverse. It does not create heat, but absorbs heat from the surrounding air. This heat is intensified and used to heat hot water in a tank. The tank is actually a traditional electric tank water heater, and its heating elements are used as a back-up for times of high demand. With the combinational of electric elements and a heat pump, these units are actually hybrid water heaters. The GE hybrid water heater and the Rheem heat pump water heater can reduce your water heating bills from 50% to 70%.
Instead of purchasing a heat pump water heater you can convert your traditional electric tank unit to a heat pump water heater, by purchasing a stand-alone heat pump made for this purpose, such as AirGenerate’s Air Tap A7.
Tankless Electric Hot Water Heaters
A tankless electric hot water heater is not limited by the capacity of a storage tank, and can deliver an unlimited amount of hot water. It is also not subject to standby heat losses, because it doesn’t store water. It is a very small unit, and because of its compactness, it can easily be mounted beneath a sink, and it is widely used as a point-of-use water heater. It is also used as a whole house water heater, but its capacity precludes applications in medium to large homes in cold climates. If you need a higher heating capacity, you can link two or more units together in a manifold configuration. If you are thinking of replacing your tank unit with a tankless model, you will need to upgrade your electrical supply to a 240V, 200 Amp service, and you will need to install a dedicated double pole breaker for each heating element. Electric tankless hot water heaters cost more than most tank models, but they have a lifespan of at least 20 years.