The importance of storage tanks

The importance of accumulation tanks when heating in boilers with manual fuel supply - lump wood and wood briquettes

Until recently, when it was not common to use accumulation tanks in the case of hot water boilers for wood and wood briquettes for central heating, the boiler was operated at a lower output than its nominal output for most of the heating season. Such operation results in a number of negative phenomena such as a decrease in heating efficiency, tarring of the boiler, releasing a large amount of harmful emissions into the air, etc. All this then leads to an unnecessary increase in heating costs, environmental degradation, more laborious cleaning of the boiler, as well as a shortening of its service life. The main reason for such boiler operation is that with a correctly designed and installed nominal output of the boiler, in a period when the external temperature is higher than that corresponding to the thermal zone in which the heated object is located, in order to prevent overheating /excess heat generation/ of the object, the user most often reduces the output heating temperature of the boiler below the optimal limit. Due to the chemical composition of the fuel, the optimal operating temperature of the boiler at the outlet is 75-85ºC, the return water temperature is min. 60-65ºC and the optimal fuel combustion temperature is 1000-1200ºC. Operating the boiler below these temperatures will achieve the desired effect of reducing excess heat and not heating the household in the short term, but at the same time all the negative phenomena listed above occur. It is important to realize that during the heating season there are only a few days or weeks when the external temperatures are at the border of the given thermal zone, i.e. when all the heat produced during boiler operation at its nominal output is actually used and consumed. Under these conditions, it is very common in practice that the boiler is operated in a temperature regime of 50-60ºC at the outlet and 30-40ºC at the return water, which is very inefficient and significantly harmful to the environment. When calculating the nominal output of a boiler, design standards mainly take into account the thermal zone in which the heated object is located, its size, degree of insulation, nature of use of the object, etc. According to these criteria, the required installed nominal output of the boiler is then calculated. This should be such that the object can be reliably heated at the lowest external temperatures of the given thermal zone. Most often, this temperature in our climate ranges from -11 to -18ºC. In reality, however, such an outdoor temperature is only approximately 1/3 of the heating season, despite the fact that outdoor temperatures can drop to -20 or even -30ºC for a short time.

The ideal solution to eliminate this problem with different outdoor temperatures is to install storage tanks in the heating system. They store and accumulate the resulting excess heat, which is then used for heating. The boiler can thus be operated during the heating season at its rated output regardless of the outdoor temperature. This modern heating comfort solution, depending on the installed boiler output and the volume of the storage tank, will ensure ecological heating, significantly save heating costs and, what is also important, will allow you to achieve thermal comfort even in severe frosts not only for the whole night, but also throughout the day, if no one is at home. The minimum recommended volume of the storage tank is 55 liters/kW. However, to increase comfort, it is advisable to install an 80 liters/kW storage tank, or even more, if space conditions allow. The acquisition costs for larger storage tanks are negligible compared to the comfort and heating efficiency gained. In such a case, it is also possible to choose a boiler with a reserve of nominal power, which will shorten the time for charging and accumulating hot water in the storage tanks.

In a heating system with a gasification boiler with a lambda probe and sufficient storage volume, heating with wood and wood briquettes becomes not only an extremely efficient form of heating, but also sufficiently comfortable. Our company offers such a solution with PYROGAS gasification boilers, which are equipped with a lambda probe, servomotors for primary and secondary air, a robust refractory concrete combustion chamber ensuring the combustion process at temperatures of 1200ºC with an intelligent fully automatic electronic control system.

More information about these boilers and storage tanks can be found on our website under the heading PRODUCTS. PYROGAS boilers are designed with a 2-5kW nominal power reserve, which ensures thermal comfort and storage comfort even in the coldest weather.

Including an accumulation tank in the heating system optimizes boiler operation, extends the boiler's service life, increases combustion efficiency, and reduces fuel consumption.
Over the life of the boiler, the investment costs for the accumulation tank will be repaid by significant savings in fuel costs and boiler maintenance.