Today there are many models of electric water heaters, but essentially they all work exactly the same. Internally they have some resistors to heat the water, depending on the water temperature, more or less resistors will turn on to have the water at target temperature as soon as possible. The usual thing is to have a thermos with a capacity of about 80L, however, if there are many of you at home, there are also models of up to 150L.
How much does an electric water heater consume?
He consumption of an electric water heater depends on several factorsThe first and most important is the capacity of said electric water heater. It is not the same to heat 150L of water and maintain the operating temperature, than to heat a small thermos of only 50L and maintain the temperature. For this reason, it is highly recommended to pay close attention to the estimated consumption when we are going to buy one of these devices for our home. Another very important aspect that you should take into account is the instantaneous power needed by your resistors to work. In small water heaters, the most common thing is that they have a power of 1000W, the medium ones have about 1500W, and finally, the largest models usually have 2000W of power.
In the example that we are going to give you, we have used a small thermos of 50L and with 1,000W of power. Logically, this instantaneous power is not working continuously, but when the thermos is at rest without heating, the consumption is close to 0Wh, while when it is heating the consumption is 1kWh. In our case, our daily consumption is between 1kWh and 1.5kWh, depending on how we use hot water.
In the following image you can see that the consumption of this electric water heater is around 11kWh per week, therefore, we have an average of approximately 1.5kWh.
Making a quick calculation, in a month our electric water heater will consume approximately 45kWh of energy. We insist that this figure varies greatly depending on the use of hot water and also the size of the thermos. Choosing the device well can help you spend less if you are not really going to need to have a bigger one. In addition, the total cost will be marked by the electricity rate that you have contracted (whether or not it has hourly discrimination), the price of the kWh, etc.
Considering these electricity consumption figures throughout the month, many people wonder if we are really going to save anything if we turn off the electric water heater at night. Next, we explain if you are really going to save something.
How much do I save if I turn it off at night?
The electric water heater turns on its resistors when the water temperature drops below a certain threshold, therefore, it is likely that between midnight and 7 in the morning it can be turned on at some point in order to maintain the target temperature. . This will cause energy consumption at a certain time during the night, if you are one of those who shower in the morning, you could program a smart plug to turn on at approximately 6:00 a.m., to have hot water, thus saving you the “ on” around 3 in the morning.
However, we have verified using a smart plug with energy measurement, that when we turn off the electric water heater at nightwhat we save by skipping those starts, we spend it later if we want to use itsince the thermos will be in operation until it reaches the operating temperature, and if the temperature is lower because we have turned it off, it will spend more until it reaches said temperature.
If you use the electric water heater daily, either first thing in the morning or at night, you will save nothing or almost nothing by turning off the electric water heater. Logically, if you have solar panels and we do not have a battery or virtual battery, then it would be advisable to transfer the consumption of the thermos to the day, and turn it off at night. It must be taken into account that the heat of the water is preserved quite well in this type of equipment, therefore, if you turn it off at 10:00 p.m. and you need hot water at 6:00 a.m., you will have hot water and you will not notice it. After around 10:00 a.m. when there is already solar production, then we proceed to turn on the thermos to make the most of the energy generated by the sun.
In case that you go on vacation, or you are going to be away from home for a couple of daysin these cases Yes, it would be recommended that you turn off the thermos to save, and turn it on when you get home. It doesn’t make sense to waste electrical energy to maintain the water temperature if you’re going to be outside. Keep in mind that, depending on the thermos we have, the water will be hot in about 30 minutes at the most, although logically this will depend on the size of the thermos and the resistances we have.
Therefore, to the question of “does the electric water heater consume more when it is turned on for 24 hours or only for a few hours?”, the answer is that it consumes the same, you will not notice a difference because what you gain by turning it off for a few hours, you “lose” » then by heating the water to the target temperature. The only thing you could do to save something is to reduce the operating temperature, instead of putting it at 50ºC, put it at 40ºC, so the resistance will activate less times.
Of course, as you have seen, it is convenient to turn it off if you are going to be on vacation for a few days. In those cases, you will see significant savings. The device will not consume electricity and you simply turn it on when you return, wait for it to heat up and that’s it. As a recommendation, if we are very strict, wait 2-3 hours if you have left it off for many days, once you turn it on, since stagnant water, at room temperature, has been able to store bacteria and it takes a few hours to eliminate them with the hot water.
