CWU is an abbreviation for "domestic hot water". In every building it is necessary for its functioning, which is why the heating device and the installation are so important. The function of the domestic hot water tank is to store enough water for the household, e.g. for a bath. Which tank should I choose?
What is a DHW tank?
The domestic hot water tank , used to heat and store hot water, is most often supplied with cold water from the water supply. The water is heated in the tank when it reaches the heating device. A special coil placed in the tank supplies water heated by the boiler or heat pump, e.g. from the central heating system. When the water temperature in the tank drops below the temperature set on the programmer, the heating device starts to heat it.
Check out the hot water tanks at the Onninen wholesaler
When choosing a DHW tank, it is worth considering the following parameters:
- capacity - from several to even 500 l; depends on the number of water collection points and the number of people in a given building
- material - and shape, e.g. cylindrical; can be made of steel or stainless steel
- installation - standing, hanging, integrated with the boiler
- insulation - usually polystyrene or polyurethane foam
- additional equipment - e.g. temperature indicator, control system, built-in additional electric heater.
The Onninen wholesaler offers two types of tanks:
- with coil
- layered
The main difference between them is the price - a coil tank is usually cheaper and is used with a single-function boiler. A layered tank, on the other hand - more expensive - is dedicated to the installation of a dual-function boiler. It is also smaller and has a more compact design, compared to a coil tank.
The main difference, however, is that a layered tank contains water arranged in layers - warm at the top, cold at the bottom. Cold water is pumped to the boiler, where it is heated and then released into circulation through an outlet at the top of the tank. In turn, a tank with a coil means heating the water in its entire volume at the same time. Heat exchange here takes place in the coil placed at the bottom of the tank.
Which DHW tank should I choose for a photovoltaic installation?
The domestic hot water tank, in the case of integration with photovoltaics, must be larger than in a traditional installation, supported by a boiler. It is estimated that the tank should be about 1.5-2 times larger than the daily demand for hot water. A too small domestic hot water tank for photovoltaics is not a good solution, because in the summer it will not be able to absorb all the heat from the collector, and too large will be more expensive, will take up more space, and in spring and autumn it may be more difficult for the water to heat up to the desired temperature. It is worth considering the larger size of the tank when planning the boiler room.
In the case of a solar tank, the key element is the system containing the lower and upper coils - the lower one is in direct contact with cold water from the water supply system, while the upper one supplies the boiler necessary to heat the water pre-heated by the lower coil.
Which DHW tank for a heat pump?
The domestic hot water tank for the heat pump, in turn, produces domestic hot water using the heating system in the building. Such a tank is equipped with a spiral coil, which creates two water circuits - the first connected to the heating device, the second to the water supply system. In order to match the tank to the heat pump installation, it should be assumed that the coil surface should not be less than 0.25 m2 per 1 kW of the heat pump. A vertical domestic hot water tank with a capacity of 150 to 300 liters is usually suitable.
At the Onninen wholesaler we can find, among others, such domestic hot water tanks as:
Wolf CEW-1-200 Layer Tank - tank dedicated to connection with heat pump, insulated with hard PU foam, enamelled, with a capacity of 180 l
Galmet 80 l enameled domestic hot water tank - tank insulated with polyurethane foam, compatible with all types of boilers.
Galmet 300 l domestic hot water tank - 300-litre, enamelled vertical tank insulated with polyurethane foam, without spiral coil.
Galmet 1000 l domestic hot water tank - ceramic-enameled and polyurethane foam-insulated vertical tank with a capacity of 1000 l.
BIAWAR heat pump tank - 400 l tank with remote control option.