ATTACK AK 100 Storage Tank (white insulation)

Product detailed description

Why the accumulation tank determines heating efficiency

ATTACK Accumulation Tank AK 100 (white insulation) is a steel accumulation (buffer) tank with a volume of 100 litres, designed for storing hot heating water from any heat source - a wood gasification boiler, heat pump, electric boiler, gas boiler or solar collectors. It is a tank without a built-in heat exchanger (sometimes also referred to as a "hydraulic separator" or "buffer tank"), which serves purely for storing heating water - heating of domestic hot water (DHW) with this type of tank is solved externally, for example via a storage water heater or a flow module.

The greatest benefit of an accumulation tank is seen when combined with a solid fuel gasification boiler, such as ATTACK DPX or ATTACK SLX. These boilers achieve the highest efficiency and cleanest combustion precisely when burning at full, rated output - i.e. when they burn a full load of wood "in one go" without throttling the air supply. Without an accumulation tank, the boiler would often have to work in a throttled mode (to avoid overheating the system), which leads to worse combustion, higher creosote formation, and lower lifespan of the boiler and chimney. With the ATTACK Accumulation Tank AK 100 (white insulation), the boiler burns the fuel at full output at once and the excess heat is stored in the water reserve in the tank - from there it is gradually drawn by the heating system according to the household's current needs, even several hours after the boiler has burned out.

The same principle also works with an electric boiler or heat pump: the 100 l tank allows the heat source to operate in longer, less frequent cycles instead of constantly switching on and off in short intervals, which extends the lifespan of the compressor/heating elements and reduces energy consumption. With smaller volumes, such as this tank, AK accumulation tanks are most often used as a supplementary buffer element in systems with an electric boiler, heat pump, or as a hydraulic separator/manifold in smaller residential and family boiler rooms, where there is no space for a large-volume tank, but it is still necessary to separate the flow circuits of the source and the heating system.

Key features of the AK100K tank

• Volume of 100 litres - designed to provide a sufficient heat reserve between individual heating cycles at a recommended heat source output of 4 - 5 kW.
• Soft, removable polyester insulation with a thickness of 100 mm - significantly reduces heat loss to the surroundings during long-term storage of hot water, while being easily removable for inspection or servicing of the tank and its ports.
• Outer insulation cover made of leatherette (PVC fabric) in white - resistant to abrasion and easy to maintain, visually acting as part of the boiler room interior, not as a "technical" element.
• 4 connection ports distributed around the perimeter of the shell and on the top/bottom of the tank, allowing connection of the heat source, heating circuits, an additional electric heating element (auxiliary heating), venting, draining and temperature sensors.
• Steel shell with an internal corrosion-resistant surface treatment, designed for a max. operating pressure of 3 bar and max. temperature of 95 °C - a safe margin compared to common operating temperatures of heating water (60-80 °C).
• Suitable for vertical position thanks to feet/stand, which at this volume facilitates precise temperature layering (stratification) - warmer water naturally stays at the top, cooler at the bottom, increasing the usability of the accumulated heat.
• Possibility of additional installation of an electric heating element (e.g. ATTACK TH100, TH102, TH103 or TH107) directly into one of the tank's ports - suitable as a backup or supplementary heat source outside the heating season or in case of a main source failure.
• Without a built-in heat exchanger - the tank is intended purely for accumulating heating water; if you also need DHW preparation via a built-in heat exchanger, check our range of AS/HR/HRS/TUV/TUVS tanks with a heat exchanger.

Technical parameters

Note: the dimensions and weight of the empty tank are approximate estimates corresponding to the given volume; we recommend verifying the exact dimensions before installation (e.g. in case of limited boiler room space or narrow doors/staircase) directly with the seller before ordering.

How to correctly choose the volume of the accumulation tank

The most commonly recommended rule when selecting an accumulation tank for a solid fuel gasification boiler is: allow approximately 20 to 25 litres of accumulation volume for each 1 kW of the boiler's rated output. This rule is based on the fact that the boiler burns a full load of fuel at full output in approximately 1.5 to 3 hours, and the heat from this load needs to be stored somewhere until the heating system gradually consumes it. With a tank volume of 100 litres, this means it is suitable for a heat source with an output of approximately 4 to 5 kW.

If, for example, you have a wood gasification boiler with an output in this range (from the ATTACK range, these are for example some models of the DPX or SLX series - both Standard and Profi versions), the tank ATTACK Accumulation Tank AK 100 (white insulation) is appropriately sized for your system. For a higher-output boiler, or if you plan to combine multiple heat sources (e.g. a wood boiler + heat pump, or a boiler + solar collectors), we recommend choosing a larger volume, or possibly connecting multiple tanks in a cascade - so that the accumulation volume corresponds to the sum of the outputs of the connected sources.

At a volume of 100 l, it also holds true that the larger the tank, the longer it can supply heat even after the boiler has completely burned out - in a well-designed and sufficiently sized system, it is common for a family house to be heated for 12 to 24 hours from a single boiler loading and a single accumulation tank, depending on the outdoor temperature, the house's heat losses and the heating system's temperature gradient (lower temperatures, e.g. with underfloor heating, allow a larger part of the stored heat to be used than high-temperature radiator systems).

It should also not be forgotten that an accumulation tank is worthwhile even in combination with automatic heat sources, such as an electric boiler or heat pump - although these sources can modulate output more smoothly than a solid fuel boiler, they still benefit from the tank by reducing the number of switching cycles, which extends the lifespan of the compressor, circulation pumps and electronics.

Connection, installation and auxiliary heating options

The ATTACK Accumulation Tank AK 100 (white insulation) is typically connected as a hydraulically separated buffer element between the heat source and the heating system (radiators, underfloor heating, fan-coil units, etc.) - the heat source charges the tank via one pair of ports, the heating system draws heat via the other pair, thereby hydraulically separating both circuits and making the system operate more stably even with fluctuating flow on the source side. The remaining ports (there are 4 in total on this tank) serve for example for fitting a temperature sensor, air vent valve, safety valve, or for connecting an additional electric heating element.

The option to fit an electric heating element is a practical solution for periods when you do not want to heat with solid fuel (e.g. outside the main heating season) or as a backup in case of a main source failure. Our range includes electric heating elements ATTACK TH100 (2.5 kW), TH102 (4.5 kW), TH103 (6 kW) and TH107 (2 kW), all with their own thermostat and G6/4" thread - compatible with the ports of this accumulation tank. We recommend selecting the element's output to match the tank volume and the desired auxiliary heating speed.

When installing the ATTACK Accumulation Tank AK 100 (white insulation), allow for sufficient handling space in the boiler room - given a diameter with insulation of approximately 650 mm and a height of approximately 780 mm (both values are approximate, see above), it is necessary to verify in advance the passability of doors, staircases and the room itself. We also recommend leaving a free space of at least 300-500 mm around the tank on the side with the connection ports, to ensure comfortable access during servicing, seal replacement or checking/refilling sensors.

We recommend filling the tank only with treated heating water in accordance with the applicable standard (e.g. EN 14868 or the boiler manufacturer's recommendation) - hard water with a high mineral content accelerates the formation of limescale on the internal walls and shortens the lifespan of the entire system, including the boiler and circulation pumps.

Connection with other heating system components

The ATTACK Accumulation Tank AK 100 (white insulation) is just one link in the heating chain. Customers most often combine it with the wood gasification boiler ATTACK DPX or ATTACK SLX (both Standard and Profi versions, output range approximately 15-35 kW), whereby the boiler output should correspond to the recommended range of 4-5 kW mentioned above. When combined with a heat pump or electric boiler, the tank serves as a hydraulic separator and heat store, reducing the number of switching cycles of the source. If you also need to prepare domestic hot water, since this particular tank is a version without a heat exchanger, we recommend supplementing the system with a separate DHW storage water heater (e.g. from the ATTACK Z range - Z100, Z125, Z160, Z200 and others, available in our range), or choosing one of the AS/HR/HRS/TUV/TUVS series models instead of this tank, which have a heat exchanger built directly into the tank.

Maintenance and inspection of the tank during operation

The ATTACK Accumulation Tank AK 100 (white insulation) requires minimal but regular maintenance. We recommend checking once a year (for example before the start of the heating season) the tightness of all 4 connection ports, the condition of the air vent valve and the safety valve of the heating circuit, as well as the overall condition of the outer insulation cover - the leatherette cover in white is resistant to normal abrasion, but in the event of mechanical damage (e.g. during moving or handling in the boiler room), we recommend repairing the damaged area in time to avoid unnecessary heat losses.

Since this is a tank without a built-in heat exchanger, the inside of the tank comes into contact only with treated heating water, not with drinking water - the risk of limescale build-up is thus significantly lower than with DHW storage tanks, but we still recommend visually inspecting the inside of the tank through an inspection opening once every few years (for example during a system shutdown), if the model is equipped with one, or at least monitoring the quality and colour of the heating water when desludging the system. Cloudy or rusty water may indicate the need for water treatment or a check for corrosion in the system.

During a long-term shutdown (e.g. outside the heating season), it is not necessary to drain the tank - on the contrary, leaving water in the system protects the inner surface from corrosion caused by exposure to air. If you plan to take the tank completely out of operation for a longer period, consult a qualified installer about the appropriate preservation procedure.

Frequently Asked Questions

Do I need to buy a heat exchanger for this tank as well?

No, this AK100K model cannot be additionally fitted with a built-in heat exchanger - it serves purely for accumulating heating water. If you need to prepare domestic hot water via a heat exchanger in a single tank, choose from our AS, HR, HRS, TUV or TUVS range.

How large a boiler can I connect to this tank?

With a volume of 100 litres, we recommend a heat source with an output of approximately 4 to 5 kW, according to the rule of 20-25 litres of accumulation per 1 kW of output. With a more powerful source, it is better to choose a larger volume or connect several tanks in a cascade.

Can the tank also be used with a heat pump or electric boiler?

Yes, the AK100K accumulation tank works equally well with a heat pump, electric boiler, gas boiler or solar collectors - in each case it reduces the number of switching cycles of the source and balances the differences between heat production and consumption.

Is insulation included in the delivery?

Yes, the tank is supplied including soft, removable polyester insulation with a thickness of 100 mm and an outer cover made of leatherette in white.

Can I fit an electric heating element into the tank for auxiliary heating?

Yes, the tank has 4 connection ports, one of which can be used to install an electric heating element, such as ATTACK TH100, TH102, TH103 or TH107 with a G6/4" thread.

What is the maximum operating pressure and temperature of the tank?

The tank is designed for a maximum operating pressure of 3 bar and a maximum operating temperature of 95 °C, which provides a safe margin over common heating water operating temperatures of 60-80 °C.

What are the exact dimensions and weight of the tank?

Approximately, the diameter with insulation is about 650 mm, the height is about 780 mm and the weight of the empty tank is about 22 kg. These are estimated values corresponding to a volume of 100 l - we recommend verifying the exact dimensions with the seller before installation in confined spaces.

What is the warranty period for the accumulation tank?

We provide a 24-month warranty on ATTACK accumulation tanks from commissioning, but no more than 30 months from the date of shipment from the factory.

Warranty and final recommendation

The manufacturer ATTACK s.r.o. provides a standard warranty of 24 months from commissioning on the ATTACK Accumulation Tank AK 100 (white insulation), but no more than 30 months from the date of shipment from the manufacturing plant. To maintain the warranty, we recommend connecting and commissioning the tank in accordance with the installation manual and applicable standards for heating technology, using treated heating water, and regularly checking the condition of the insulation and the tightness of the connection ports. We are happy to advise on choosing the right tank volume by phone or email - just state the type and output of your heat source and we will recommend the most suitable model from the ATTACK range.