Tank volume
The total volume of the tank. For models with a storage tank (see “
Storage tank volume”), the full volume is usually indicated, taking into account the storage tank volume; accordingly, the working volume of the tank will be the difference between the total volume and the volume of the storage tank. However, these details for each model should be clarified separately.
The choice for this parameter depends primarily on the scale of the heating system and the power of the heater. Too small a tank will not be able to accumulate enough heat, and too
large a tank will lead to unnecessary energy consumption, and it will take up a lot of space. The most general rule says that for every kilowatt of power of the boiler, there should be from 25 to 50 litres of the working volume of the hot water storage tank. There are more detailed calculation formulas that take into account various additional factors; they can be found in special sources.
Heat exchanger volume
The volume of the heat exchanger(s) with which the storage tank is equipped.
For more information about such equipment and its functions, see "Number of heat exchangers". And the volume of the heat exchanger is a rather specific service parameter, used mainly for some special calculations. It is also believed that the larger the volume of the heat exchanger, the higher the thermal inertia of the system and the more energy is wasted. However, it most often does not play a decisive role.
Max. tank temperature
The maximum allowable temperature of the heating medium in the tank, in other words, the temperature that the tank can withstand without consequences for an unlimited time.
The choice for this indicator depends on the specs of the heating system which is planned to use the tank. The expected temperature of the medium should not be higher than the maximum allowable temperature in the storage tank — otherwise, the latter will experience abnormal loads and may fail at any time.
Max. temperature in heat exchanger
The maximum temperature allowed for the heat exchanger(s) used in the tank.
For details on the heat exchangers, see "Number of heat exchangers". And the temperature of the heating medium supplied to them should not exceed the maximum allowable value. Otherwise, the device may fail at any time.
Max. heat exchanger pressure
The highest pressure allowed for the heat exchanger(s) used in the tank.
For details on the heat exchangers themselves, see "Number of heat exchangers". And the pressure should not exceed the maximum allowable value. Otherwise, the circuit may fail or be damaged at any time.
Number of heat exchangers
The number of heat exchangers provided in the design of the storage tank.
The simplest version of storage tanks are tanks
without heat exchangers. They are designed for traditional use in the heating system — to remove excess heat, equalize the temperature characteristics and provide the system with heat in the event of a malfunction in the heater.
Heat exchangers installed in the storage tank can perform two main functions: removing heat from the tank or providing additional heating. One of the most popular options is to work as a water heater for a hot water supply system (in this case,
one heat exchanger is enough). As an opposite example (additional heating), a heat exchanger connected to a solar collector can be given. There are storage tanks that have several heat exchangers (
2 and
3 heat exchangers) and allow several additional applications at once. Anyway, the specific specialization of heat exchangers for each model should be specified separately.
Insulation material
It is the material of the heat-insulating layer applied in the tank.
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Polyurethane foam. It has excellent performance specs and surpasses all other materials of a similar purpose in terms of the quality of thermal insulation. Polyurethane foam is quite expensive, but it is almost invisible compared to the total cost of storage tanks. Thanks to all this, this option is perhaps the most popular in modern storage tanks.
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Polyester fibre. Thermal insulation based on synthetic fibre made of polyester. The actual capabilities of such insulation directly depend on the density of the fibre, and the cost of the filler also depends on the density. Therefore, when assessing the overall quality of such thermal insulation, it is worth looking first of all at the price category of the tank. In general, the insulating specs of polyester fibre are average, somewhat inferior to expanded polystyrene.
— Styrofoam. One of the remarkable features of this material is its very low weight (because more than 90% of the volume of polystyrene foam is air). In terms of thermal insulation coefficient, it is one and a half to two times inferior to polyurethane foam; however, it is also cheaper.
— Mineral wool. Thermal insulation based on fibres formed from minerals and a binder (eg. phenol). It has a low cost and fairly decent heat-insulating specs. At the same time, mineral wool tends to
...accumulate moisture, and this leads to a loss of insulating abilities; in addition, there is evidence that such a filler can release harmful substances. Therefore, when using a heat accumulator with such insulation, special care must be taken to ensure that its outer shell remains intact.Country of origin
The country of origin of the storage tank.
In evaluating this feature, two points must be taken into account. Firstly, the country of origin is often indicated not by the place of actual production, but by the homeland of the brand under which the heat accumulator is presented on the market. Secondly, the actual quality of the product will depend on the integrity of the manufacturing company. So when choosing, you should focus not so much on the country of origin, but on the reputation of a particular brand. And you should pay attention to The country of origin only if you fundamentally want (or do not want) to support a manufacturer from a certain country.
