Connection To The Accumulation Tanks - ATTACK SLX20 Instructions For Use Manual

5.4.8 CONNECTION TO THE ACCUMULATION TANKS

System of the connection is based on warming the accumulation tanks, where is the accumu-
lated warmth from accumulation tanks gradually drained according to the requirements of
heated space. During the bioler operation at full output are accumulation tanks warmed at 80–
90 °C. Heating with accumulation tanks in connection with ATTACK SLX boiler brings several
advantages. Main advantages are higher efficiency, lower fuel consumption, prolonged lifetime
of the boiler, more frequent operation, minimal creation of acids and condensates, higher com-
fort, lower risk of boiler overheating and fuel saving.
Recommended volume of the accumulation tank for ATTACK SLX 25 boiler is 2000 l (for other
outputs see technical parameters). Boiler is able to produce 180 kWh of energy at one loading of
the hard wood to the feeding chamber (it is ca. 7 hours of operation at full 25 kW output). It cor-
respond to charge of 2 000 l accumulation tank from 20 °C to 90 °C if there is no energy offtake
(that is why is necessary to keep in mind by choosing the size of accumulation tank, that boiler
must be operated according to the size of accumulation tank. It means that, if you have 2000 l
tank, load the wood chamber fully. If you have 1000 l tank, load the chamber halfway – if there is
no energy offtake from the accumulation tank). If the accumulation tank is charged (bottom
temperature of the accumulation tank achieves 70 °C) and boiler achieved set boiler tempera-
ture, do not load the wood to the boiler. If you would load the wood to the boiler in this state,
wood would not be combusted (boiler has already achieved set temperature and fan has turned
off). It would get dry and condensates would create in the feeding chamber, what lowers boiler
lifetime. It is necessary to fill the wood at the time when the accumulation tank is almost dis-
charged.
Example 1:
Outside temperature of the environment is −5 °C and heat loss of the object is 10 kW by this
temperature. Boiler has 25 kW at the full output operation. Accumulation tank with volume
2000 l is discharged (its upper and bottom temperature is 20 °C). The heating system (to cover
heat loss) drains 10 kW output from accumulation tank and boiler has 25 kW output, accumula-
tion tank will be heated by the output of 15 kW – difference between them. 15 kW output makes
energy of 105 kWh by full loading of the chamber with hard wood and time of the operation ca.
7 hours. Energy of 105 kWh warms accumulation tank from 20 °C to 65 °C. It means, that this is
the safe economic operation without putting the boiler out of operation or draining excessive
warmth to the waste (boiler was cooled by the aftercooling circuit). Boiler is able to cover the
heat loss for up to 15 hours at one wood loading.
Example 2:
Outside temperature of the environment is +3 °C and heat loss of the object is 5 kW by this tem-
perature. Boiler has 25 kW at the full output operation. Accumulation tank with volume 2000 l is
discharged (its upper and bottom temperature is 20 °C). The heating system (to cover heat loss)
drains 5 kW output from accumulation tank and boiler has 25 kW output, accumulation tank will
be heated by the output of 20 kW – difference between them. 20 kW output makes energy of
140 kWh by full loading of the chamber with hard wood and time of the operation ca. 7 hours.
Energy of 140 kWh warms accumulation tank from 20 °C to 80 °C. It means, that this is the safe
economic operation without putting the boiler out of operation or draining excessive warmth to
the waste. If the heat loss of the object would be constant all the time – 5 kW, charged accumu-
lation tank would be able to cover heat loss for about 28 h, what is together with operation time
up to 35 hours without need of wood loading.
That is why it is necessary to keep in mind, that boiler should be loaded only with amount of
wood necessary for charging the accumulation tank, because pointless overheating might lead
to putting the boiler out of the operation or removing excessive warmth to the waste. This is
uneconomical and requires activation of the safety element – aftercooling loop.
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