What is better: an instantaneous water heater or storage tank?
News | 19. 3. 2018
A life of a modern person without hot water is difficult to imagine. But what is the most economical and efficient way of heating water? Unfortunately, there is no universal answer. Choosing a method of heating water depends on several factors: the character of the building, the method of heating, availability of a gas connection, or the number of points of delivery.
However, when the household does not take hot water from a central source, they usually decide between an instantaneous water heater or using an indirectly heated storage tank.
What are the advantages of the aforesaid types of water heating?
Instantaneous Water Heater Saves Space and Money
The instantaneous water heater is called that because it heats water as it is flowing through it, i.e., it only turns on when the hot water is needed. It does not use a large external storage tank where water is heated in advance. That considerably saves space, so this type of water heater can be recommended for flats where it is not possible to install a water tank.
Ideally, the water heater is installed at the point of delivery (bathtub, washbasin, sink) so you do not need to wait for hot water and use too much cold water.
Disadvantages of Instantaneous Water Heater
If you decide to purchase an electric instantaneous water heater or an electric boiler with flow heating, the corresponding low voltage distribution is required at the installation site. The flow water heating is demanding on instantaneous power consumption. However, it is reduced by other electric appliances that you use at home. Therefore, the water heater requires its own circuit breaker. As it is not possible to heat up water in advance when the tariff is low, the operation of an instantaneous water heater is more expensive. You can regulate water temperature within the range from 30 to 60°C.
Condensing Gas Boilers with flow heating of Wather
For gas boiler with water flow heating eliminates the need for equity breaker to heat flow is fully used natural gas. After turning the tap, the boiler automatically closes and the burner under the exchanger starts at full power. Even so, it takes a few seconds for the entire system to heat up, and after the end of consumption, the residual heat remains unused. Therefore, this type of heating is not suitable for places with frequent short-term hot water demand.
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Hot Water in an External Storage Tank
The greatest advantage of an external heated storage tank is in the provision of maximum heat comfort. Unlike the instantaneous water heater, the output temperature of the water does not depend on the actual number of points of delivery. Temperature never drops suddenly, for example, when someone is taking a shower and another person starts washing their hands.
The boiler with a storage tank continuously heats up water, so it does not have high demands on instantaneous energy consumption as the water heater. It also manages gas consumption better. It only turns on when the water temperature in the storage tank drops below the set limit value and heats up the entire contents. It also offers a greater variability in the range of water temperature regulation, which ranges from 30°C to 90°C. The recommended setting for an economical operation is 55°C, during which, among other things, scale that reduces the boiler output does not collect. An external storage tank is the most convenient solution for family homes and households with more members and points of delivery.
Disadvantages of External Storage Tank
The disadvantages include the higher initial investment in the purchase of the storage tank and the space needed for its installation. When it is installed far from the point of delivery (usually in the boiler room), you will have to wait for the hot water. That means that you will need to drain cold water from the pipes first before hot water starts flowing. If the distance between the boiler and the point of delivery is longer, it is better to install the storage tank at the point of delivery, i.e., further away from the boiler. Good insulation of hot water piping is naturally required to prevent any heat losses.
And last, but not least, you need to select an optimal size of the storage tank. If it is too small, you will not have enough hot water. On the other hand, if it is too large, you will be heating up too much water, which will make its operation more costly. The installation company should help with the selection.
Looking for a compromise? It exists!
There is a compromise between both methods of heating and that is a boiler with a built-in storage tank. Such boilers are mostly installed on the wall and they are not much bigger than boilers without a storage tank thanks to their compact design. However, there is an insulated tank under the casing with a capacity of dozens of litres that can cover smaller consumption of hot water (washing hands, brushing teeth, doing the dishes), and when there is a higher consumption demand, the boiler switches to the instantaneous heating mode without reducing the temperature of the delivered water. Our product portfolio includes the PREMIUM Condens boilers where you can also find a boiler with a storage tank. It is the THERM 25 KDZ 5 boiler that uses an integrated stainless storage tank to deliver hot water, with a capacity of 55 litres. This version is suitable both for flats and family homes.