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Energy efficiency and savings in the home > Hot water

Modern water heating systems are of two types: instant water heating is provided by a gas-powered heater that can also be used for a space heating system; storage heating can be provided by a gas-powered system for collective facilities or by electric storage tanks for individual homes. If sufficient space is available, it should always be remembered that a water heating facility based on solar panels with a supporting hot-water generation facility is the most energy-efficient and environment-friendly system. Instant heating systems heat water on demand. Their main disadvantages are listed below: - Considerable amounts of water and energy are wasted before a suitable water temperature is reached at the point of use, especially if it is located at a certain distance from the boiler. - The boiler goes on every time that hot water is required. By going on and off continuously, there is a considerable increase in consumption and the equipment deteriorates more quickly. - These systems usually have a very limited capability of supplying hot water to two points of consumption at the same time. Generally speaking, hot-water storage systems are more recommendable from the standpoint of energy efficiency. They may comprise a heat-generating unit (such as a boiler or a heat pump) with a storage tank, or a storage tank with an electrical resistor. Systems formed by a boiler with a storage tank are those most often used for centralized hot-water storage facilities. With these systems, once the water is heated it is stored in an insulated tank for later use. These systems are more efficient than individual facilities and offer the following advantages: - They are easy to combine with thermal solar panel systems for water heating. - They prevent the continuous turning on and off of the boiler, which operates in one stretch when required and is consequently more efficient. - The amount of power required to supply hot water to a group of users is much lower than the sum of the power consumptions of the individual systems that would be needed to provide the same supply. - The stored hot water can be used at the same time at two or more points of consumption. Electric hot-water storage tanks, on the other hand, are hardly recommendable from the standpoints of energy-efficiency and cost. When the temperature of the water stored in the tank descends to a set temperature, an auxiliary resistor goes into operation. That is why the tank should not only be well insulated but also be controlled by a programmable timer that is set for the hours when it is really necessary, This means that hot-water storage systems are more efficient than systems providing instant water heating without storage. It is very important for the storage tanks, if any, and the hot-water distribution piping to be well insulated. Opening the hot-water tap for only a short time is not efficient: hot water is not supplied instantly and, consequently, water and energy are wasted. It is recommendable to take showers instead of baths since energy and water are saved in this way. As opposed to 30 to 40 litres per shower, a bath uses between 100 and 130 litres (4 to 5 times more water). Additionally, if low-consumption shower heads are used, a 50% saving in water consumption and, consequently, in energy can be achieved. Aerators can be installed in taps to save water and energy. Also, if you still have separate taps for cold and hot water, it is best to change them for a single handle mixer.

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