ATTACK 12 EKO COMBI - stationary gas cast-iron boiler 12 kW

Product detailed description

ATTACK COMBI - stationary cast iron gas boiler

Stationary gas boilers with a cast iron heat exchanger are among the most durable and longest-proven heating solutions on the market. Cast iron as an exchanger material is highly resistant to corrosion and thermal shock and tolerates less gentle operating conditions (frequent switching, fluctuations in return water temperature) better than thin-walled steel or aluminium exchangers. Thanks to this, cast iron boilers have long enjoyed a reputation as robust and reliable devices suitable not only for ordinary family houses, but also for larger buildings, operations, workshops, small businesses, or multi-generational homes with higher heat consumption.

Another advantage of the cast iron body is easy maintenance and serviceability - the cast iron exchanger is usually made up of individual sections (segments), which means that if one of them is damaged, only the affected section can be replaced instead of the entire exchanger. In the long run, this can mean lower servicing costs compared to one-piece exchangers. The stationary design (a boiler standing on the floor, not wall-mounted) also simplifies installation for higher outputs and makes it easier to connect to a naturally draught chimney, which is commonly used in both older and newer boiler rooms.

The model you are currently viewing belongs to the ATTACK EKO COMBI range and is designed for a nominal heat output of 12 kW. It is a stationary gas boiler in COMBI design - in the context of this cast iron ATTACK range, this means that the boiler itself does not have its own (built-in) domestic hot water (DHW) preparation. To heat hot water, the boiler must therefore be supplemented with an external indirect DHW storage tank (e.g. from the ATTACK Z-series - see the "How to connect" section below). This type of solution (boiler + separate storage tank) is common and proven especially where there is a demand for greater comfort of hot water draw-off at several points simultaneously, as storage water heaters can cover even a temporarily higher DHW consumption better than instantaneous heating.

The ATTACK EKO COMBI range is the basic, entry-level line of cast iron stationary ATTACK boilers. It is intended for customers looking for a simple, reliable and affordable heating solution for a family house or smaller operation without unnecessary extra features. EKO COMBI builds on the proven design of a cast iron exchanger and basic automation, making it one of the most accessible stationary cast iron gas boilers in the ATTACK range. It is a choice for those who expect primarily functionality, long-term operational stability and low acquisition costs, and are willing to trade advanced comfort features for a lower price.

Why a cast iron exchanger and not a steel or aluminium one?

When choosing a stationary gas boiler, customers often ask why they should opt for a cast iron exchanger when cheaper steel or lighter aluminium solutions are also available on the market. The answer is mainly related to the long-term durability of the material. Cast iron has higher thermal inertia than thin-walled steel, which in practice means a calmer, less "nervous" combustion process and less stress on the material during sudden changes in return water temperature (for example when a cold system starts up after a longer shutdown). At the same time, cast iron is naturally more resistant to condensation corrosion, which can gradually damage thin-walled steel exchangers if operated in an unsuitable regime (long-term low return water temperature).

Another practical argument is the already mentioned sectional (segmented) design. A cast iron exchanger is not made of a single piece but of several sections stacked on top of each other and joined by sealing gaskets. If one section were to become damaged over the years of operation (which is unlikely even with cast iron, but theoretically possible, for example due to mechanical damage or extreme neglect of maintenance), a service technician can replace only the affected section without having to replace the entire boiler body. With one-piece steel or aluminium exchangers, this option generally does not exist, and damage to the exchanger means replacing the entire boiler or at least the entire exchanger block.

The disadvantage of cast iron is higher weight (see the indicative figure in the technical parameters table below) and a somewhat slower thermal response when starting up from cold - however, for a stationary boiler intended for long-term, mostly continuous operation (not frequent on/off cycling as with a cottage used a few times a year), these are rather marginal disadvantages compared to the benefit of a long service life and easier repairability.

Who is this boiler suitable for

The ATTACK EKO COMBI stationary cast iron boiler with an output of 12 kW is a suitable choice especially where a boiler room is available (it is not designed to be wall-mounted like standard wall-hung combi boilers) and where a naturally draught chimney is available or planned. Typically this includes:

• Family houses with their own boiler room or utility room, where a long service life and easy serviceability of the equipment matter
• Larger buildings and multi-generational houses with higher heat consumption, where the robustness of the cast iron body is appreciated
• Smaller operations, workshops, guesthouses or cottages with year-round or almost year-round operation, where investment in a higher-quality body pays off through a longer service life
• Renovations where an older cast iron boiler is being replaced and an existing chimney and gas supply sized for the given output are available

On the other hand, if you are looking for a compact wall-mounted solution for an apartment or a smaller housing unit, or a boiler with its own fast hot water preparation without the need to install a separate storage tank, a cast iron stationary COMBI boiler is probably not the best choice - in that case, we recommend consulting us about a more suitable alternative from ATTACK's wall-hung condensing boilers.

Key features

• Stationary (floor-standing) design with a cast iron heat exchanger - high resistance to corrosion and thermal shock
• Nominal heat output of 12 kW, fuel: natural gas (LPG version on request/according to specific order specifications)
• COMBI design = boiler without its own DHW preparation, intended to work together with an external indirect storage tank (e.g. ATTACK Z-series)
• Sectional (segmented) cast iron exchanger - in case of damage, allows replacement of a single section instead of the entire body
• Connection to a naturally draught chimney (atmospheric combustion)
• Robust construction suitable also for larger buildings and operations with higher heating output requirements
• Basic, proven equipment without unnecessary extras - emphasis on simplicity and low acquisition price
• The delivery includes the boiler body itself, including the burner and basic control system - external DHW storage tank, circulation pump, expansion vessel, chimney accessories and room thermostat are not included in the basic price unless explicitly stated

Technical parameters

Note: dimensions and weight are indicative estimates based on the output category and typical design of cast iron sectional boilers of this class - we recommend verifying the exact value for a specific unit in the manufacturer's current technical data sheet or directly with us before ordering, especially if you are planning precise construction preparation of the room or niche for the boiler.

How to connect: boiler + external DHW storage tank

Since this is a COMBI design without its own domestic hot water preparation, this boiler must be connected together with a separate (external) indirect DHW storage tank. For this purpose, ATTACK offers the so-called Z-series of storage tanks (e.g. Z100PLUS, Z125PLUS, Z100NTR, Z125NTRA, Z160NTRA, Z125OKC, Z160OKC, Z200OKC and other versions including wall-mounted horizontal OKCV variants) - these storage tanks are sold as a separate product and are not included in the boiler's delivery or price.

For this output range (up to approx. 18 kW), a smaller storage tank volume from the ATTACK Z-series is usually sufficient, e.g. ATTACK Z 100 PLUS OKH NTR/HV, Z 100 OKC/NTR/HV or the wall-mounted version Z 125 OKC - the choice between a 100 and 125 l volume mainly depends on the number of people in the household and how many hot water draw-off points (bathroom, kitchen, etc.) will be used simultaneously.

In short, the connection principle is as follows: the boiler heats the heating (heat transfer) water, which circulates both to the heating system (radiators, underfloor heating) and through the exchanger (coil) in the DHW storage tank, where it transfers heat to the domestic water. Switching between the heating circuit and heating the storage tank is usually handled by a three-way valve (in the ATTACK range, e.g. models OT02 or OT44), controlled either by the boiler's electronics or by a separate room thermostat/controller. The exact connection (pipe routing, placement of pumps, safety and mixing valves) depends on the specific layout of the boiler room and on whether it is a simple two-pipe system or a more complex system with several heating circuits - we recommend having the final connection designed and carried out by an authorized heating/gas specialist who will also take into account locally applicable standards and regulations for connecting a gas appliance.

When ordering the boiler and the storage tank, we are happy to help you choose a suitable combination of boiler output and storage tank volume according to the number of people in the household and the number of simultaneously used hot water draw-off points - please do not hesitate to contact us before purchasing if you are unsure about the correct choice.

Maintenance and servicing in practice

As with any gas appliance, a regular service inspection (usually once a year, carried out by an authorized service technician) of the ATTACK stationary cast iron boiler is not only a condition for maintaining the warranty, but above all a prerequisite for safe and economical operation. For cast iron boilers, servicing usually includes checking and, if necessary, cleaning the exchanger and burner of soot and dust, checking the tightness of the joints between individual sections, checking the chimney draught and the flue gas path, and verifying correct combustion settings.

Compared to modern condensing boilers, maintaining an atmospheric cast iron boiler is generally simpler and cheaper - for example, there is no need to take care of a condensate siphon or an exchanger sensitive to low return water temperature. On the other hand, keep in mind that atmospheric cast iron boilers of this design do not achieve the efficiency of the most modern condensing solutions, which is a common and fair trade-off between higher initial robustness/simplicity and the highest possible energy efficiency. If the lowest possible gas consumption at any cost is a decisive criterion for you, we are happy to discuss alternatives from ATTACK's condensing range with you as well.

Frequently asked questions

1. Is domestic hot water (DHW) heating included in the price of this boiler?
No. This is a COMBI design without its own DHW preparation - the boiler only heats the heating water. To heat domestic hot water, an external indirect storage tank must be added (e.g. from the ATTACK Z-series), which is ordered and paid for separately.

2. Which DHW storage tank is suitable for a 12 kW boiler?
For this output range (up to approx. 18 kW), a smaller storage tank volume from the ATTACK Z-series is usually sufficient, e.g. ATTACK Z 100 PLUS OKH NTR/HV, Z 100 OKC/NTR/HV or the wall-mounted version Z 125 OKC - the choice between a 100 and 125 l volume mainly depends on the number of people in the household and how many hot water draw-off points (bathroom, kitchen, etc.) will be used simultaneously.

3. How does the EKO COMBI range differ from the other ranges in ATTACK's cast iron COMBI offering (EKO, PLQ, KLQ, E, EZ)?
In short: it is the basic, entry-level range in ATTACK's cast iron boiler offering - simpler equipment, lower acquisition price, suitable for customers who prioritize functionality and price over additional comfort.

4. What type of fuel is the boiler designed for, and can it be converted to another fuel?
In its basic version, the boiler is designed for natural gas. An LPG (propane-butane) version is available on request/according to specific order specifications - we recommend stating this requirement when ordering or inquiring with our sales team in advance.

5. What is the warranty on this boiler?
ATTACK stationary gas boilers are covered by a warranty of 30 months from commissioning, but no more than 36 months from the date of dispatch from the manufacturer's warehouse. An extended 5-year warranty applies to the cast iron exchanger body. The exact warranty terms are governed by the warranty certificate supplied with the specific unit, and the prescribed commissioning conditions must be met (usually by a professional service technician).

6. Can the boiler be connected to an existing naturally draught chimney?
Yes, this is an atmospheric boiler designed to be connected to a naturally draught chimney. The suitability of a specific chimney (diameter, height, material) must be assessed individually, ideally during a site visit or in cooperation with a chimney sweep/inspection technician, especially if the boiler is being connected to an older brick chimney.

7. Can the boiler be connected to a system with several heating circuits (e.g. radiators + underfloor heating)?
Yes, combining several circuits with different heating water temperatures is common - however, this requires adding a mixing circuit with its own pump and control (in the ATTACK range, e.g. sets DPP25007/DPP25008 or ESBE versions DPP25020-DPP25022). We recommend discussing the connection design with a heating engineer or directly with our team.

8. Can the boiler be ordered without a DHW storage tank, just the body itself?
Yes - this product represents the boiler body itself. The DHW storage tank, circulation pump, chimney accessories, three-way valve and room thermostat/controller are ordered as separate items according to the needs of the specific installation - we are happy to prepare a complete list of accessories tailored to your project.

9. What is the difference between this atmospheric cast iron boiler and a modern condensing boiler?
An atmospheric cast iron boiler operates with a higher flue gas temperature and does not use condensation of water vapour from the flue gases to gain additional heat, so its efficiency does not reach the values of modern condensing boilers. In exchange, it offers a simpler construction, lower sensitivity to the temperature of the return heating water, and generally simpler, cheaper maintenance without the need to deal with condensate drainage. The choice between a cast iron atmospheric and a condensing solution is always a trade-off between initial robustness/simplicity and the highest achievable efficiency - we are happy to help you weigh both directions according to your priorities.

10. Where can I order the boiler and how does delivery work?
You can order the boiler directly through the atria.sk e-shop. When ordering, we also recommend considering a suitable DHW storage tank from the Z-series and any additional accessories (chimney parts, three-way valve, circulation pump, room thermostat) so that you have a complete solution ready for installation. If you have any doubts when choosing the boiler + storage tank + accessories combination, please contact us before ordering - we are happy to advise so that you don't order something you won't ultimately need, or, on the contrary, so that nothing essential is missing.

Warranty and service

ATTACK EKO COMBI stationary cast iron gas boilers are covered by a standard warranty of 30 months from commissioning, but no more than 36 months from the date of dispatch from the manufacturer's warehouse (whichever period occurs first). The manufacturer provides an extended 5-year warranty on the cast iron exchanger body itself. To claim the full warranty period, the commissioning conditions set by the manufacturer must be met (usually by a professional service technician authorized for this activity), and a proper service book/warranty certificate must be kept. If you have any questions about the warranty, servicing, or choosing suitable accessories (DHW storage tank, circulation pump, chimney parts, controls), please do not hesitate to contact us - we are happy to help you choose and order a complete solution tailored to your needs.