ATTACK AK 50 Storage Tank (white insulation)

Product detailed description

Why the buffer tank determines heating efficiency

The ATTACK Buffer Tank AK 50 (white insulation) is a steel accumulation (buffer) tank with a volume of 50 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 - domestic hot water (DHW) heating with this type of tank is handled externally, for example through a storage water heater or a flow module.

The biggest benefit of a buffer tank is seen when combined with a solid fuel gasification boiler, such as the ATTACK DPX or ATTACK SLX. These boilers achieve the highest efficiency and cleanest combustion precisely when burning at full, rated output - that is, when they burn a whole load of wood "in one go" without throttling the air supply. Without a buffer tank, the boiler would often have to operate in a throttled mode (to avoid overheating the system), which leads to poorer combustion, higher tar formation and shorter boiler and chimney lifespan. With the ATTACK Buffer Tank AK 50 (white insulation), the boiler burns the fuel at full output at once and the excess heat is stored as a reserve of water in the tank - from there the heating system gradually draws it 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: a 50 l tank allows the heat source to operate in longer, less frequent cycles instead of constantly switching on and off for short intervals, which extends the lifespan of the compressor/heating elements and reduces energy consumption. With smaller volumes, such as this tank, AK buffer tanks are most often used as a supplementary buffering element in systems with an electric boiler, heat pump, or as a hydraulic separator/manifold in smaller apartment and family house boiler rooms, where there is no space for a large-volume tank, but the flow circuits of the source and heating system still need to be separated.

Key features of the AK50K tank

• Volume of 50 litres - designed to provide a sufficient heat reserve between heating cycles at the recommended heat source output of 2 - 2.5 kW.
• Soft, removable polyester insulation 100 mm thick - significantly reduces heat loss to the surroundings during long-term storage of hot water, while being easy to unfasten for inspection or servicing of the tank and fittings.
• Outer leatherette cover (PVC fabric) in white - resistant to abrasion and easy to maintain, visually blending in as part of the boiler room interior rather than looking like a "technical" element.
• 4 connection ports distributed around the shell and on the top/bottom of the tank, allowing connection of the heat source, heating circuits, a supplementary electric heating element (booster heating), venting, draining and temperature sensors.
• Steel shell with an internal corrosion-resistant surface treatment, rated for a max. operating pressure of 3 bar and a max. temperature of 95 °C - a safe margin above typical heating water operating temperatures (60-80 °C).
• Suitable for vertical installation thanks to feet/a stand, which at this volume makes precise temperature stratification easier - warmer water naturally stays on top, cooler water at the bottom, increasing the usable share of the accumulated heat.
• Option to additionally install an electric heating element (e.g. ATTACK TH100, TH102, TH103 or TH107) directly into one of the tank ports - suitable as a backup or supplementary heat source outside the heating season or in case of main source failure.
• Without a built-in heat exchanger - the tank is designed purely for accumulating heating water; if you also need to prepare DHW via a built-in heat exchanger, check out our range of AS/HR/HRS/TUV/TUVS tanks with 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 with the seller before ordering, especially before installation (e.g. if the boiler room space, doorways or staircase are limited).

How to correctly choose the buffer tank volume

The most common rule of thumb when choosing a buffer tank for a solid fuel gasification boiler is: allow approximately 20 to 25 litres of buffer volume per 1 kW of rated boiler output. This rule is based on the fact that the boiler burns one 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 50-litre tank, this means it is suitable for a heat source with an output of approximately 2 to 2.5 kW.

If, for example, you have a wood gasification boiler with an output in this range (from the ATTACK range, these include some models from the DPX or SLX series - both Standard and Profi versions), the ATTACK Buffer Tank AK 50 (white insulation) is appropriately sized for your system. For higher boiler output, or if you plan to combine several heat sources (e.g. a wood boiler + heat pump, or a boiler + solar collectors), we recommend choosing a larger volume, or connecting several tanks in a cascade - so that the buffer volume matches the sum of the outputs of the connected sources.

With a 50 l volume, 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 large system, it is common for a family house to be heated for 12 to 24 hours from a single boiler load and one buffer tank, depending on the outdoor temperature, the heat losses of the house and the temperature gradient of the heating system (lower temperatures, e.g. with underfloor heating, allow a larger share of the stored heat to be used than high-temperature radiator systems).

It's also worth remembering that a buffer tank is worthwhile 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 saves the lifespan of the compressor, circulation pumps and electronics.

Connection, installation and booster heating options

The ATTACK Buffer Tank AK 50 (white insulation) is typically connected as a hydraulically separated buffering 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, while the heating system draws heat via the other pair, hydraulically separating both circuits so the system runs 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 a supplementary electric heating element.

The option to fit an electric heating element is a practical solution for periods when you don't want to heat with solid fuel (e.g. outside the main heating season) or as a backup in case the main source fails. Our range includes the 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 buffer tank. We recommend choosing the element's output to match the tank volume and the desired heating speed.

When installing the ATTACK Buffer Tank AK 50 (white insulation), make sure there is sufficient handling space in the boiler room - given a diameter with insulation of approximately 580 mm and a height of approximately 650 mm (both values approximate, see above), it is necessary to check in advance the clearance of doors, staircase and the room itself. We also recommend leaving free space of at least 300-500 mm around the tank on the side with the connection ports, to ensure comfortable access for servicing, gasket replacement or checking/topping up sensors.

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

Connection with other heating system components

The ATTACK Buffer Tank AK 50 (white insulation) is only one link in the heating chain. Customers most often combine it with a wood gasification boiler ATTACK DPX or ATTACK SLX (both Standard and Profi versions, output ranges of approximately 15-35 kW), where the boiler output should match the recommended range of 2-2.5 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 adding a separate DHW storage water heater to the system (e.g. from the ATTACK Z series - Z100, Z125, Z160, Z200 and others, available in our range), or choosing one of the models from the AS/HR/HRS/TUV/TUVS series instead of this tank, which have a heat exchanger built directly into the tank.

Maintenance and inspection of the tank during operation

The ATTACK Buffer Tank AK 50 (white insulation) requires minimal but regular maintenance. We recommend checking once a year (e.g. before the start of the heating season) the tightness of all 4 connection ports, the condition of the air vent valve and the heating circuit safety valve, as well as the overall condition of the outer insulation cover - the leatherette cover in white is resistant to normal wear, but in case of mechanical damage (e.g. during moving or handling in the boiler room), we recommend repairing the damaged spot promptly to avoid unnecessary heat losses.

Since this is a tank without a built-in heat exchanger, the inside of the tank only comes into contact with treated heating water, not 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 once every few years (e.g. during a system shutdown) through the inspection opening, if the model is fitted 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), there is no need to drain the tank - on the contrary, leaving the water in the system protects the inner surface from corrosion caused by air exposure. 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 separately for this tank?

No, this AK50K 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 series.

How large a boiler can I connect to this tank?

For a volume of 50 litres, we recommend a heat source with an output of approximately 2 to 2.5 kW, according to the rule of 20-25 litres of buffer volume per 1 kW of output. For a higher-output 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 AK50K buffer tank works equally well with a heat pump, electric boiler, gas boiler or solar collectors - in every case it reduces the number of switching cycles of the source and balances the difference between heat production and consumption.

Is insulation included in the delivery?

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

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

Yes, the tank has 4 connection ports, one of which can be used to fit an electric heating element, for example 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 rated for a maximum operating pressure of 3 bar and a maximum operating temperature of 95 °C, providing a safe margin above typical 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 580 mm, the height is about 650 mm, and the weight of the empty tank is about 15 kg. These are estimated values corresponding to a volume of 50 l - we recommend verifying the exact dimensions with the seller before installation in confined spaces.

What is the warranty period for the buffer tank?

We provide a 24-month warranty from commissioning for ATTACK buffer tanks, but no more than 30 months from the date of dispatch from the factory.

Warranty and final recommendation

The manufacturer ATTACK s.r.o. provides a standard warranty of 24 months from commissioning for the ATTACK Buffer Tank AK 50 (white insulation), but no more than 30 months from the date of dispatch from the factory. To maintain the warranty, we recommend connecting and commissioning the tank in accordance with the installation manual and applicable heating technology standards, using treated heating water and regularly checking the condition of the insulation and the tightness of the connection ports. We are also happy to advise on choosing the right tank volume by phone or email - just let us know the type and output of your heat source and we will recommend the most suitable model from the ATTACK range.