A review of the electric water heaters for residential whole-house and point-of-use water heating, with the focus on tank-type and tankless heaters.
Find out how electric models work, advantages, about main components, manufacturers, best models, and are if they are a good investment or not.
To size the electric water heater correctly and avoid an oversized model, which can further lead to higher costs or insufficient hot water delivery, consider the following tips:
The most common sizes are 40, 50, and 60 gallons, but if you were happy with the performance and amount of hot water in your old unit, then go with that size.
For 2-3 people, the recommendation is to buy a 40-gal unit; for 4-5 people, buy a 50-gal unit, and for more than five people, go with the 60- or even 80-gal unit.
In the case of the tankless, it is essential to know the temperature rise (desired outgoing temperature minus (–) incoming (ground) water temperature) and how much hot water is needed per application:
If the temperature of the groundwater is 50 F and you would like to have hot water with a temperature of 140 F, and planning to run a shower, washing machine, and dishwasher simultaneously, look for a tankless unit which can provide 6 GPM (2+2+2) of hot water with a temperature rise of 90 F (140-50).
For the shower, you will need an average of 20 gallons, for shaving 2 gallons, hands and face washing 4 gallons, food preparation 5 gallons, and an automatic dishwasher 14. Keep in mind that only 70% of the available capacity can be used. So if you need 50 gallons of hot water, you would buy a 60-80-gal unit.
Electric hot water heaters with the storage tank are the most popular type in the US and Canada. They are big, heavy, but reliable, utilizing proven technology. There are various types such as the conventional tall, medium or short, Lowboy, Tabletop, POU (point-of-use), where the models with a 50-gallon capacity are the most popular.
Users and plumbers love this type because they are simple, easy to operate, service, and troubleshoot. There is no venting required, they are cheap and can be used in most homes.
The following components are used in most of the traditional type heaters:
Conventional electric water heaters utilize one or two heating elements (lower and upper) for water heating and corresponding thermostats for temperature control. As the heating elements are fully immersed, they can transfer more than 90% (even 99%) of heat.
No matter is the tap open or not, water inside the tank is being heated and kept at the pre-set temperature.
Cold water from the home plumbing fills the tank through the dip tube, which is submerged almost to the bottom of the tank.
One of the heating elements is turned ON when the thermostat senses that the water temperature is below the set value. Every heating element carries the thermostat, which is mounted against the tank surface.
When the hot water tap is open, hot water from the top of the tank is drawn, and since the level drops, fresh but cold water gets inside the tank. The lower temperature initiates the heating elements to heat the water to the set value. Once it reaches the set value, the thermostat turns the heating element OFF, waiting for another "call."
Electric hot water heaters are equipped with safety elements as well, such as a high limit switch that prevents water from boiling or reaching the temperatures over the given on the thermostat, and if the thermostat fails.
Tankless electric water heaters are small, wall-hanging, and provide hot water only when there is demand. These are often installed under the sink and used at the point of service while delivering hot water in an endless and continuous supply.
As they heat water while it is moving through the heat exchanger, there is no standby heat loss. With on-demand heating, water is always fresh, delivered fast, and with substantial energy savings.
Electric water heaters with tankless technology heat water on demand. They don't utilize the tank, but the heat exchanger where water is heated. They are small, compact and lightweight, often installed on the wall.
Tankless models produce endless hot water and only when there is demand. A great example is Stiebel Eltron and its popular model Tempra, DHC, and DHC-E models.
When there is a "call" for hot water (the tap is open), cold water passes over the heating element and is heated instantaneously. Based on its power, the tankless water heater can supply one or more fixtures at the same time while working as the point-of-use or whole-house heater.
Heat pumps or hybrid heaters are ultra-efficient electric heaters that provide high energy factors of two or more, are Energy Star compliant, and eligible for tax credits and rebates. Heat pumps are great for the attic, garage, and basement installation. It is the favorite type of those homeowners who are looking to go "green." The most popular are AO Smith, GE GeoSpring, and Rheem.
Note: See here how electric water heaters work
When searching for the best electric water heaters, look for high-efficient models. These units save energy, heat fast but are not Energy Star compliant. None of the electric tank- and tankless-type heaters are eligible for government grants unless they utilize heat pump technology. Heat pumps are the only electrical appliances that are Energy Star approved.
If you prefer proven technology and a traditional, bulky water heater, and your family has 4-5 members go with the 50-60-gal unit. This type will be enough to deliver hot water to every application of your home. Our recommendation is Marathon.
If your home lacks space and you would like to have an endless supply of hot water, which is heated on-demand only, go with the tankless option. Tempra and EcoSmart are good options.
Tankless never runs out of hot water, as long as you have an electric connection, it conserves energy and water as you don’t have to wait for the heater to heat up, it is convenient to use, easy to install, and very safe. Also, it costs less.