Panels photovoltaic solar energy

Electric water heater and electric water heater

Electric water heater and electric water heater

The electric heater differs from other types of water heaters because it uses electricity to raise the temperature of the water. 

These heaters have different capacities, so that they can store different amounts of hot water, so that it can be adapted according to the needs of family and domestic consumption.

Electric heaters use an electrical resistance to generate heat. As an electric current circulates through it, the electric charges collide with the resistor atoms and part of their energy is converted into thermal energy. This thermal property is described by Joule's law.

In solar installations, the electric heater is a good option if you have installed photovoltaic panels and you do not want to install solar thermal energy collectors. In both cases, the energy is obtained from renewable energy, but to obtain thermal energy, solar thermal energy offers better energy efficiency. 

In some countries, manufacturers are required to put energy labels on electrical appliances (heaters, heat pumps, household appliances, etc.) so that the consumer can identify their energy class.

Types of electric heaters

There are two types of electric heaters depending on their operation:

  • Electric storage water heater, if it works by collecting water in a tank to heat it for a certain period of time and then keep it warm throughout the day and night. This type of heater is also known as an electric boiler.

  • Instant water heater, if it works by heating water instantly without accumulating it.

Electric water heater

An electric water heater is a device used to heat water using an electrical resistance. The hot water is stored in a thermally insulated boiler or tank for when it is needed in the home.

There are three types of electric water heaters:

  • Vertical electric water heater.

  • Horizontal electric water heater.

  • Reversible or universal electric water heater.

How does an electric water heater work?

Understanding the operation of an electric water heater is very simple and similar to a gas heater but instead of using natural gas or LP gas, it is powered by electricity.

The main components of a thermal heater are: electrical resistance, probe and insulation.

As we already know, these devices can store different capacities of water, which they contain in a single water tank.

The electrical resistance is the main responsible for the transfer of heat to the water. Depending on the model, the maximum temperature it can reach varies between 60 ° C and 70 ° C. When the water has reached its maximum point, it turns off.

Therefore, it is at this point that a temperature sensor is used. When the temperature drops too low it sends a signal to the electrical resistance, which will turn on again so that the water returns to the maximum temperature.

However, the insulation will have the task of keeping the water at its maximum temperature point as long as possible, so that the probe does not have to send its signal to the electrical resistance so quickly.

Components of an electric water heater

The electric storage water heater collects, heats, stores and supplies hot water by means of some elements. In particular, this bulky appliance, whose flow rate can vary from 10 to 120 liters depending on the capacity of the water heater, works thanks to the following components: 

  • An insulating steel housing in which a temperature indicator may be present.

  • An insulated and enameled tank to collect and store water heated to a stable temperature.

  • A hose to connect the boiler to the water tap.

  • A highly conductive metal electrical resistance that can be in direct or indirect contact with cold water to diffuse heat as efficiently as possible.

  • A hose through which hot water can reach the plumbing system.

  • A thermoregulator to regulate resistance. It is a device that deactivates the water heater when the optimum water temperature is reached, which is maintained by the resistance.

  • A flange, a mechanical part to join the pipes; 

  • A safety valve applied to the cold water inlet to expel excess water in case the pressure rises dangerously; 

  • an anti-overheating system.

Regarding the connections of the electric water accumulator, it should be noted that the water enters from the right and then exits from the left.

Instant Electric Water Heater

Instantaneous electric heaters are water heaters equipped with a series of internal electrical resistors to heat the water that passes through an internal circuit.

The main advantages of this system are:

  • They don't need a water tank

  • They only consume energy when hot water is needed.

The electric water heaters can carry two types of electrical resistances: sheathed and armored.

The armored heating elements have a direct contact with the water, and therefore, the heating is faster. However, when they are used in areas with hard water, they deposit limescale from the water directly on the resistance, they lose part of their effectiveness and their useful life is reduced.

How does an instant electric heater work?

The instantaneous electric water heater is a low-consumption appliance that works with an electric induction system to heat the sanitary water of a water system.

This appliance is distinguished by its limited size, the absence of a tank and the immediate heating of the water, by means of a great and powerful resistance, which occurs when the water tap is opened.

In addition, the instant water heater allows you to install it in the smallest spaces, for example above the washing machine or under the sink.

In this regard, it should be noted that the instant electric water heater works with considerable power.

It is also important to emphasize that the instant electric water heater works at full power only when the water tap is turned on and then turned off by closing the tap itself.

Advantages of the instant water heater

The main advantage of having a thermal heater is obvious, because it is about having hot water, however, these devices have other points in their favor:

  • Installs quickly and easily.

  • The water heats up instantly.

  • The water temperature will always be the same, so you can forget about temperature changes while you shower.

  • You can save a lot of water, since you won't need to let it run for a while, until it reaches the desired temperature.

  • Its maintenance is very simple and inexpensive.

Disadvantages of the instantaneous electric heater

While it is good to have a thermal heater at home, this one has some cons:

  • It consumes a lot of electricity, however, this can be minimized if you keep the appliance plugged in while heating the water, so that the changes in your electricity bill are not so high.

  • Hot water is limited, because once the water stored in the tank runs out or cools, you will have to wait for it to reheat; the good news is that this happens very fast.

  • It takes up more space, as they are somewhat larger than other types of water heaters or boilers.

Maintenance tips for your electric water heater.

Here are some simple steps to maintain an electric heater:

  1. Disconnect the water heater from the mains.

  2. Close the cold water inlet.

  3. Place a bucket under the heater to catch the water that will come out of the tank and avoid unwanted spills.

  4. Open the pressure valve by moving the lever. (usually down), when you do this, you will hear and see air and some water vapor escape. If not, you should check the pressure valve as it may be damaged; if so, you will need to replace it.

  5. Disconnect the cold water connection from the drain valve and connect a hose that goes to the bucket.

  6. Open the drain valve and wait for the tank containing the accumulated water to drain completely. Wait for the sediment to come out.

  7. After completing the previous step, close the drain valve, disconnect the hose, and close the pressure valve.

  8. Open all the taps in the house where the hot water comes out and connect the cold water inlet to the heating tank.

  9. When the water comes out of the open taps, you can watch them close one at a time.

  10. Connect the water heater to the mains, turn it on and you are ready to supply hot water again.

Publication Date: October 26, 2021
Last Revision: October 27, 2022