All You Need to Know about Electric Water Heaters

All You Need to Know about Electric Water Heaters
August 2, 2012 Lorelie

When it comes to water heaters for residential use, the most popular type is the electric water heater.  Depending on the size of your home and your needs, you can actually find electric water heater units that come in various sizes ranging from the small size such as the point-of-use or lowboy, medium size such as the tankless, and the big tank-type that is utilized for commercial and residential water and radiant heating.

Electric Point-of-use Water Heaters

Electric point-of-use water heaters, the tank-type, typically have small capacities that are commonly installed in bathrooms, kitchens and under the sink.  This type of water heater is sufficient enough for small on-demand hot water jobs such as shaving, hand washing and dishwashing.

Electric Tankless Water Heaters

Electric tankless water heaters are typically popular in many homes because they can provide hot water on demand, which means that the water never runs out.  Generally, these electric tankless water heater units have a compact, small design which saves a whole lot of space.  You can practically install them wherever you like – in the kitchen, bathroom, closet, or even under the sink.

Due to the fact that these electric tankless water heaters are less likely to leak and are not prone to sediments and hard water, they maintain their efficiency for a very long time.

Electric Tank-Type Water Heaters

Main Parts of an Electric Tank-Type Water Heater

  • Cylindrical steel tank – holds the hot water.  Sizes for residential homes are 40, 50, 60 and 80 gallons.  In order to keep the rust out of the water, the steel tank is equipped with a bonded glass liner.
  • Insulation – helps keep the heat inside the tank longer.
  • Thermostats that control the water temperature inside of the tank.
  • Cold water inlet and hot water outlet, or pipes.
  • Heating elements that heat the water.  There are usually two of them.
  • Drain valve which allows the user to drain the tank.
  • TPR valve (temperature and pressure relief valve) – a safety device.
  • Sacrificial anode rod – prevents corrosion.

How Does an Electric Tank-Type Water Heater Work?

The process of heating water in an electric tank-type water heater is very simple.  Usually, there are two heating elements which are submerged in the water (one at the bottom and then one in the middle of the tank), and two thermostats (one for each heater).

  • First, the cold water enters the tank heater via the dip tube and fills it from the bottom up.
  • The topmost thermostat which controls the upper heating element and is pressed against the tank, is turned on when there is a need.
  • The cold water then becomes warmer.  By the time it reaches the pre-set temperature, the power is then switched from the upper to the lower heating element.
  • The bottom thermostat which controls the lower heating element, is turned on until the water temperature reaches the pre-set value.
  • A safety device, the high-limit switch, reacts if in case the water becomes too hot by cutting the power to the heating elements.
  • When you open the hot water tap, hot water is drawn from the top of the water tank.  Simultaneously, cold water enters the tank, and then drops the temperature which triggers the thermostat.  After that, the entire water heating process starts all over again.
  • If in case there is an excessive pressure buildup in the tank caused by a high water temperature, another safety device known as the pressure relief valve reacts to stop it.

Some Basic Things You Must Know about Electric Water Heater Components

The thermostat is a switch that can sense a change in water temperature.  The thermostat switch closes up to let the current flow, and it opens up when the temperature of hot water reaches its pre-set value.

The current passes through the electric-resistant heating elements, power is then delivered and it heats the water to the correct pre-set temperature.

The heating elements continue on carrying the current until the thermostats are contented.  The heating elements are considered to be very efficient as they provide about 99% of the available heat to the surrounding water.

On some tanks, the thermostat possesses a mark that shows the maximum temperature and where to set the temperature that provides scald protection and energy savings.

The advantage of electric water heaters over gas or oil-fired water heaters is that the heating elements have a much longer life expectancy because they tend to wear and tear less.

Tips on How to Save Money on Electric Tank-Type Water Heaters

In order to minimize the loss of heat through the bottom of the electric tank water heater, put the tank over a thick layer of firm thermal insulation.

Lowering the temperature setting by 10 degrees F can save you about 2% to 5% of your electricity costs.

Keep in mind that an electric water heater unit is a much better option than fuel-fired water heater units especially if the installation is limited to the middle part of your home, and the price of an electric water heater is more affordable.

Advantages of Electric Water Heaters

  • Easy to install.
  • It can be installed in many places inside your home.
  • It can be installed close to the actual point-of-use area.
  • Even if it has a low-recovery rate, it has a rather large tank capacity.
  • It comes in various sizes and models.
  • No venting is needed as there are no exhaust gases or fumes produced when in operation.
  • They are cheaper in price as compared to gas water heaters.
  • It has a longer service lifespan.
  • Its energy efficiency can go up to 99%.
  • They are smaller, about 1/3 only as compared to the gas water heater units.
  • They need very little maintenance and they are very easy to clean.
  • If there are any problems in the unit, they are easy to diagnose, troubleshoot and repair.
  • Overall, the unit is practically safe for everyone to use.

Disadvantages of Electric Water Heaters

Low recovery rate.  This means that it takes longer to heat the water.  One simple solution to this actually is to cover them up with a specially-designed blanket or “jacket”.

Expensive to operate, considering electricity cost is more expensive than gas.

They are known to be high-amperage appliances, and when the hot water is used during peak times, their operating cost increases as well.

They lose heat through the tank surface, as a result of standby losses.

Even if the installation is practically little to no cost at all, you still must consider having an adequate electrical supply for it in order to support this high-output hot-water heating device.

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