Standard ATTACK AK buffer tank Verified quality of ATTACK products

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ATTACK AK / AS standard buffer tank

Heat storage for boilers and heating systems.

The ATTACK AK tank stores excess heat from a heat source and releases it to the system as needed. The AS version adds one heat exchanger for connecting a solar system. Actual model capacities range from 204 to 4,940 litres.

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Category: Buffer tanks

204–4 940 lActual capacity
100 mmRemovable insulation
AS SolarSolar-system connection
Robot-weldedHigh-precision welding

Heat storage

Use excess energy later

The AK tank stores energy from a heat source. When paired with a solid-fuel boiler, it enables operation at rated output; the manufacturer associates this mode with lower fuel consumption and reduced tar and acid formation.
Cutaway view of a house with a heating system and buffer tank

Lower fuel consumption with a biomass boiler

Use less fuel at full output and optimal efficiency.

Combining a boiler with a buffer tank allows it to operate at its rated output. This reduces the formation of tar and acids during combustion and helps extend the service life of the boiler and chimney.
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Connection diagram details

AK/AS connections and dimensions

Numbers 1 to 8 mark connections on both the AK and AS drawings; number 9 marks sensor positions on the AK drawing on the left. AS and RS are the solar heat-exchanger connections. D1 is the diameter without insulation, D2 is the diameter with insulation, and R is the tank height when tilted, without insulation. Select a marker for details.

Connection diagram for standard ATTACK AK and AS buffer tanks

Komponent 1 / 12

Boiler flow connection

Connection 1 is the boiler flow connection. It measures 1½″.

Komponent 2 / 12

Unused connection

Connection 2 is available for use and measures 1½″.

Komponent 3 / 12

Unused connection

Connection 3 is available for use and measures 1½″.

Komponent 4 / 12

Heating-circuit return

Connection 4 is the heating-circuit return. It measures 1½″.

Komponent 5 / 12

Radiator-circuit flow

Connection 5 is the heating-circuit flow for radiators. It measures 1½″.

Komponent 6 / 12

Underfloor-heating circuit flow

Connection 6 is the heating-circuit flow for underfloor heating. It measures 1½″.

Komponent 7 / 12

Gas, oil, or pellet boiler return

Connection 7 is the return for a gas, oil, or pellet boiler. It measures 1½″.

Komponent 8 / 12

Wood-boiler return

Connection 8 is the wood-boiler return. It measures 1½″.

Komponent 9 / 12

Solar-system or heating sensor connection

Position 9 is for a solar-system or heating sensor. The connection measures ½″; the diagram shows it at several heights.

Komponent AS / 12

Solar-system flow connection

The AS connection is the solar-system flow on a tank with a heat exchanger. It measures 1″.

Komponent RS / 12

Solar-system return connection

The RS connection is the solar-system return on a tank with a heat exchanger. It measures 1″.

Komponent D1 / 12

Tank diameter without insulation

D1 indicates the tank diameter without the insulation layer. The dimension depends on the tank model; see the technical data for each model.

Detailed specifications

Technical data

Actual capacity differs from the nominal model designation. When planning the installation, also consider the diameter, height, weight, and space required for transport and installation.

ParameterUnitAK 200 KAK 300 KAK 400 KAK 500 KAK 800 KAK 1000 KAK 1500 KAK 2000 KAK 2500 KAK 3000 KAK 4000 KAK 5000 KAS 500 KAS 800 KAS 1000 KAS 1500 K
Position 1–5mm9251,1101,1201,4051,5451,7351,7551,9552,0052,2052,3852,2851,4051,5451,7351,755
Position 2–6mm7057908151,0131,1351,2551,3451,4091,4651,6001,7301,6801,0131,1351,2551,345
Position 3–7mm4554605156217257758208629159851,0651,065621725775820
Position 4–8mm205210210230315295375315375375405455230315295375
RS positionmm————————————230315295375
AS positionmm————————————710725860895
L – maximum length of electric heating elementmm5506007007008408401,0501,1501,2501,3001,4501,6507008408401,050
Diameter without insulationmm5005506506507907901,0001,1001,2001,2501,4001,6006507907901,000
Diameter with 100 mm insulationmm7007508508509909901,2001,3001,4001,4501,6001,8008509909901,200
Heightmm1,1401,3501,3801,6601,8402,0302,0952,3102,3872,5962,8192,7701,6601,8402,0302,095
Height with 100 mm insulationmm1,1901,4001,4301,7101,8902,0802,1452,3602,4372,6462,8692,8201,7101,8902,0802,145
R – tilting dimension without insulationmm1,1571,3681,4021,6781,8642,0522,1422,3532,4382,6432,8722,8451,6781,8642,0522,142
Maximum operating pressure of tankbar3333333333333333
Maximum operating temperature of tank°C95959595959595959595959595959595
Solar heat-exchanger aream²————————————1.82.433.6
Solar heat-exchanger volumel————————————11.915.919.823.7
Maximum operating pressure of solar heat exchangerbar————————————10101010
Maximum operating temperature of solar heat exchanger°C————————————105105105105
Tank volumel2042894054887329151,4491,9802,4352,9153,8194,9404747138911,420
Weightkg46607381109118201235271363475578118157172265

Product materials

Download documents

ATTACK buffer tank operating manual PDF · English ATTACK boiler hydraulic connection diagrams PDF · Slovak ATTACK AS energy labels PDF · English ATTACK AK energy labels PDF · English ATTACK buffer tank certificate ZSV 0607 PDF · Slovak Hydraulic connection diagrams for biomass boilers PDF Technical data PDF

Customer support

Design and installation support

ATTACK service partners provide prompt support throughout the year. Contact an expert for help designing the connections and choosing a suitable capacity.

Service support

Need help choosing?

Choose a tank capacity to suit your system

The right capacity depends on the heat source, heating circuits, and the space available for transport and installation.

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