ATTACK Z 160 OKC Wall-mounted Tank

Product detailed description

The ATTACK Wall-mounted Storage Tank Z 160 OKC is an indirectly heated wall-mounted domestic hot water (DHW) storage tank with a volume of 160 litres, with a standard heat exchange area, designed to be hung on the wall next to a wall-mounted or floor-standing ATTACK gas boiler. The tank does not contain its own heat source - the water inside is heated indirectly, by means of heating water from the boiler, which circulates through an internal steel heat exchanger.

The wall-mounted OKC design saves floor space in the boiler room or utility room, since the tank hangs on the wall on the same bracket or next to the boiler. It is therefore a suitable choice especially for apartments, smaller houses and spaces where there is not enough room for a floor-standing (free-standing) tank.

Key features

• Inner tank made of steel sheet with a high-quality enamelled (glazed) surface resistant to corrosion and limescale build-up
• Magnesium protective anode against electrochemical corrosion of the tank - extends the life of the storage tank and is easily replaceable during servicing
• Hardened PUR foam thermal insulation covered with an outer casing, which minimises heat losses during hot water storage
• Internal steel heating exchanger (coil) with a heat exchange area of 1.0 m² for indirect water heating from the boiler
• Suitable for connection to floor-standing ATTACK gas boilers (EKO COMBI, PLQ COMBI, KLQ COMBI, E COMBI, EZ COMBI series) as well as other heat sources with a correctly sized heat exchanger
• Opening / pocket for a thermometer or thermostatic probe to control heating
• Outlet for an optional electric heating element (purchased separately) for additional heating outside the heating season, when the boiler is not running
• Drain valve for easy draining and maintenance of the tank
• Robust construction with enamelling tested according to European standards for potable water tanks
• Manufactured under the ATTACK brand - a proven Slovak manufacturer of heating technology

Type and design

The basic wall-mounted design Z 160 OKC is equipped with a standard single-circuit heat exchanger, sufficient for a typical household of 2-4 people with a boiler of adequate output. If the household has higher peak hot water demand, we recommend considering the sister model labelled "160/1m²" with a larger heat exchange area.

Structurally, this is a wall-mounted (hanging) storage tank - it is fixed to the wall using a supplied or separately sold wall bracket, usually in close proximity to the boiler, so that the connecting pipes are as short as possible and heat losses in the distribution are minimal.

Technical specification

Note: dimensions and weight are approximate estimates based on the volume and design type of the tank; exact values can be found in the manufacturer's technical data sheet or requested when ordering.

How indirect domestic hot water heating works

The ATTACK Wall-mounted Storage Tank Z 160 OKC is not a heat source - it has no burner or electric heating cartridge of its own (that is only an optional accessory). The heating principle is as follows: heating water heated in the ATTACK gas boiler flows via a circulation pump into an internal steel heat exchanger (coil) submerged in the tank. Through the wall of the exchanger, it transfers heat to the domestic water, which fills the internal volume of the 160-litre tank. The domestic water and heating water never physically meet - they are separated by the wall of the heat exchanger, so there is no mixing or contamination of the potable water by the heating medium (which may contain corrosion inhibitors and other additives).

Heating is controlled by the boiler's control system in cooperation with a temperature sensor (surface-mounted or immersed in the tank's pocket) and usually a three-way switching valve, which, when there is a demand for DHW, redirects the flow of heating water from the radiator circuit to the tank's heat exchanger. This gives domestic hot water preparation priority over space heating, and the household has hot water available practically immediately after the circulation pump starts.

The advantage of this solution over instantaneous heating (a combi boiler without a storage tank) is that the tank stores a supply of already heated water - it is therefore possible to draw a larger amount of hot water at once (for example, filling a bathtub) without the output limitation that instantaneous heating in a boiler has.

How to choose the right storage tank for your boiler

When choosing the volume of a Z series storage tank (100, 125 or 160 litres), it is recommended to base the decision primarily on the number of people in the household and hot water usage habits:

• 100 litres - suitable for 1-3 people, an apartment or smaller family house with standard consumption (showering, kitchen, bathroom without a bathtub or with occasional filling)
• 125 litres - suitable for 3-4 people, a typical family house, a combination of shower and bathtub
• 160 litres - suitable for 4-5 or more people, households with higher demand for simultaneous draw-off (for example, more bathrooms)

This particular model, the ATTACK Wall-mounted Storage Tank Z 160 OKC, has a volume of 160 litres with a heat exchange area of 1.0 m². The larger the heat exchange area, the faster the tank can "recharge" the hot water consumed at the same boiler output - when choosing between a standard and an "enlarged" heat exchanger (where both are manufactured, e.g. the OKC 125/160 series), also consider the output of your boiler: for boilers with higher output (25-30 kW), it is worth opting for the variant with a larger heat exchanger, so that its output can actually be used for fast DHW heating as well.

The storage tank itself does not generate heat - it must be connected to a suitable source, usually a floor-standing cast-iron ATTACK gas boiler (EKO COMBI, PLQ COMBI, KLQ COMBI, E COMBI or EZ COMBI series), which has provision for connecting an external DHW storage tank via a three-way valve. These boilers themselves prepare DHW only instantaneously or not at all, and it is precisely the external Z series storage tank that adds the hot water storage function to them. When combined with a heat pump or solar system, we recommend choosing specialised models from the HP or SOL series (other products in our range), which have a heat exchanger sized for lower heat carrier temperatures.

Installation and connection

The wall-mounted storage tank is fixed to a load-bearing wall using a supplied or separately purchased mounting bracket, usually in close proximity to the boiler. The wall must be able to bear the weight of the filled tank (empty weight approx. 37 kg + approx. 160 kg of water), so for plasterboard or other non-load-bearing partitions, a suitable fastening system must be used, or the tank should be placed on a load-bearing masonry wall.

The cold and hot water connections and the heat exchanger circuit are connected according to the manufacturer's diagram, usually directly to the boiler or via a manifold. We recommend installing shut-off valves, a safety valve on the cold water inlet, and a check valve. Installation should be entrusted to a qualified plumber/heating engineer, who will also connect the control system (temperature sensor, three-way valve) in cooperation with the boiler's control unit.

Maintenance and servicing

To ensure the longest possible service life of the ATTACK Wall-mounted Storage Tank Z 160 OKC, we recommend following a regular service cycle:

• Checking the magnesium anode at least once a year (more often with harder water) - a worn anode must be replaced in time, otherwise it loses its protective function and corrosion of the tank from the inside accelerates
• Descaling/draining the tank via the drain valve once every 1-2 years, especially in areas with harder water, where limescale and sludge accumulate at the bottom of the tank
• Checking the safety valve on the cold water supply - regularly turning it to verify its function and the patency of the drip pipe
• Checking the tightness of connections and the heat exchanger at each annual boiler service inspection
• With hard water, consider installing a water softening or dosing device, which significantly extends the life of both the heat exchanger and the tank

Regular maintenance is also a condition for warranty acceptance in the event of a fault caused by corrosion or limescale deposits.

Safety, standards and legislation

The ATTACK Wall-mounted Storage Tank Z 160 OKC is a pressure vessel that must be installed and operated in accordance with applicable technical standards and regulations, in particular STN EN 12897 (indirectly heated water heaters) and related regulations for pressure equipment. Correct installation always includes a properly sized safety valve on the cold water inlet, which protects the tank against excessive overpressure during heating - its discharge/drip pipe must be led freely into a space with a slope and must not be closed off or blocked in any way.

We also recommend installing an expansion vessel on the cold water side (especially if there is a check valve or pressure-reducing valve on the inlet that prevents water from flowing back into the water mains during heating and thermal expansion). Without an expansion vessel, the safety valve may open repeatedly, leading to unnecessary water loss.

Installation, connection to the boiler's heating circuit, and initial commissioning should always be entrusted to a qualified person authorised to install gas and heating equipment. Only professionally performed installation and a regular annual service inspection (together with the boiler inspection) are also a prerequisite for warranty acceptance in the event of a claim. The 160-litre storage tank is intended exclusively for heating potable (domestic) water in the internal distribution systems of buildings, not for other technological purposes.

Position in the ATTACK product range

The ATTACK Wall-mounted Storage Tank Z 160 OKC belongs to the Z series - indirectly heated DHW storage tanks from ATTACK, which, in addition to this model, also includes other volumes (100, 125, 160, 200 litres), designs (floor-standing OKH NTR/HV, wall-mounted OKC, horizontal wall-mounted OKCV) and special variants (e.g. with an additional 2.2 kW electric heating element built into the tank body, a solar version SOL with two heat exchangers, or the HP version designed for heat pumps). Thanks to the wide range of variants, it is possible to find a storage tank tailored exactly to the layout of your boiler room and the needs of your household.

This model is recommended primarily in combination with floor-standing cast-iron ATTACK gas boilers of the EKO COMBI, PLQ COMBI, KLQ COMBI, E COMBI and EZ COMBI series, which have provision for connecting an external DHW storage tank, since the boiler itself does not include a DHW storage tank.

Frequently asked questions

Do I need a boiler in addition to the 160 l storage tank, or does it work on its own?

The ATTACK Wall-mounted Storage Tank Z 160 OKC is an indirectly heated type - it does not generate heat on its own. It must always be connected to a heat source, most often a floor-standing ATTACK gas boiler with provision for an external DHW storage tank (via a three-way valve), or another suitable source with a sufficiently sized output.

Can the storage tank also be connected to a heat pump or solar collectors?

Yes, in principle it can, however we recommend rather the specialised models of the HP series (for heat pumps, with a large-area exchanger for a low-temperature source) or SOL (with an additional solar heat exchanger), which are directly sized for these sources. This model of the Z series is primarily intended for a classic gas boiler.

How long does hot water stay warm in the tank without heating?

Thanks to the high-quality PUR insulation, standby losses are low, but the exact time depends on the room temperature and the difference compared to the water temperature. In general, under normal conditions the tank keeps water at a usable temperature for a period of several hours up to overnight; for longer standby periods without the boiler running, it is advisable to add the optional electric heating element.

Is it possible to add electric heating?

Yes, the tank has a provision (pocket/outlet) for an electric heating element with a thermostat, which is purchased separately (for example, output of 2-6 kW depending on the model). This allows DHW heating even outside the heating season, when the boiler is switched off.

What is the warranty on the storage tank?

We provide a 5-year warranty on the insulated tank, and 24 months on other parts (e.g. anode, seals, accessories) from the date of dispatch, provided the installation conditions and regular maintenance (especially checking and replacing the anode) are observed.

How often does the magnesium anode need to be replaced?

We recommend checking the anode at least once a year during the boiler service inspection. With more aggressive or harder water, more frequent checks and an earlier replacement date may be necessary - a worn anode loses its anti-corrosion function.

What is the difference between the 100, 125 and 160 litre volumes?

The difference is mainly in capacity - a larger volume means more accumulated hot water available at once (e.g. when filling a bathtub while showering simultaneously), but also larger physical dimensions and weight. The choice depends on the number of people in the household and water usage habits.

Can a standard wall bear the weight of the filled storage tank?

The filled tank weighs a total (empty weight + 160 l of water) of roughly 197 kg, so it must be anchored to a load-bearing masonry wall with suitable anchors, or a separate stand can be used. The wall-mounted storage tank must not be installed on thin non-load-bearing partitions (e.g. plasterboard) without additional reinforcement.

Warranty and service

For ATTACK brand products, we provide a warranty of 5 years on the insulated tank of the storage tank (provided that the installation conditions and regular maintenance, including checking and replacing the magnesium anode, are observed) and 24 months on other parts and accessories from the date of dispatch from production. Service and spare parts (e.g. anodes, seals, accessories) are available in Slovakia. If you have any questions about selection, installation or claims, do not hesitate to contact us - we will be happy to advise you on choosing a suitable boiler or control system for this storage tank as well.