ATTACK 15 E COMBI - stationary gas cast iron boiler 12-15 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 long-proven heating solutions on the market. Cast iron as an exchanger material is highly resistant to corrosion and thermal shock, and it handles less gentle operating conditions (frequent cycling, fluctuating return water temperature) better than thin-walled steel or aluminium exchangers. As a result, cast-iron boilers have long enjoyed a reputation as robust and reliable appliances suitable not only for ordinary family houses but also for larger buildings, facilities, workshops, small businesses, or multi-generational houses with higher heat demand.

Another advantage of the cast-iron body is easy maintenance and serviceability - a cast-iron exchanger typically consists of individual sections (segments), so if one of them is damaged, only that particular 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 floor-standing boiler, not wall-mounted) also simplifies installation at higher outputs and makes it easier to connect to a natural-draught chimney, which is commonly used in both older and newer boiler rooms.

The model you are currently viewing belongs to the ATTACK E COMBI range and is rated for a nominal heat output of 12-15 kW. It is a stationary gas boiler in COMBI design - within this cast-iron ATTACK range, this means that the boiler itself does not have its own (built-in) domestic hot water (DHW) preparation. Heating domestic hot water therefore requires adding an external indirect-fired DHW cylinder (e.g. from the ATTACK Z-series - see the "How to connect" section below). This type of solution (boiler + separate cylinder) is common and proven especially where higher comfort of hot water draw-off at several points simultaneously is required, since cylinder-type heaters can cover even a temporarily higher DHW demand better than instantaneous heating.

The ATTACK E COMBI range follows on from KLQ COMBI and, within the ATTACK cast-iron lineup, represents an even higher equipment class. E COMBI boilers are intended for customers who, besides functional reliability, also require higher operating comfort. The exact technical differences compared to the KLQ COMBI range (e.g. the specific burner type, control details) are not available in full detail in our source data - if you need to know exactly how E COMBI differs from KLQ COMBI at your specific output level, we will gladly verify this before purchase and help you choose based on the manufacturer's current technical documentation.

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 lower material stress during sudden changes in return water temperature (for example, when starting up a cold system 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 under an unsuitable operating 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 connected with sealing gaskets. If one section were to become damaged over years of operation (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 whole boiler or at least the entire exchanger block.

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

Who is this boiler suitable for

The ATTACK E COMBI stationary cast-iron boiler with an output of 12-15 kW is a suitable choice especially where a boiler room is available (it is not designed for wall mounting like common combi wall-hung boilers) and where a natural-draught chimney is available or planned. This typically includes:

• Family houses with their own boiler room or utility room, where long service life and easy serviceability of the appliance matter
• Larger buildings and multi-generational houses with higher heat demand, where the robustness of the cast-iron body is appreciated
• Smaller facilities, workshops, guesthouses, or cottages with year-round or nearly year-round operation, where the investment in a higher-quality body pays off over 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 small utility core, or a boiler with its own fast hot water preparation without the need for a separate cylinder, a stationary cast-iron COMBI boiler is probably not the most suitable choice - in that case, we recommend consulting us about a more suitable alternative from the ATTACK wall-hung condensing boiler range.

Key features

• Stationary (floor-standing) design with a cast-iron heat exchanger - high resistance to corrosion and thermal shock
• Nominal heat output 12-15 kW, natural gas fuel (LPG version available on request/according to specific order specification)
• COMBI design = boiler without its own DHW preparation, intended to work with an external indirect-fired cylinder (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 natural-draught chimney (atmospheric combustion)
• Robust construction suitable even for larger buildings and facilities with higher heating output requirements
• Increased operating comfort within the ATTACK cast-iron range
• The delivery includes the boiler body itself, including the burner and basic control - the external DHW cylinder, circulation pump, expansion vessel, chimney accessories, and room thermostat are not included in the base price unless explicitly stated

Technical parameters

Note: dimensions and weight are given as an approximate estimate based on the output category and the usual construction 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 recess for the boiler.

How to connect: boiler + external DHW cylinder

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

For this output level (up to approx. 18 kW), a smaller cylinder volume from the ATTACK Z-series is generally 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 depends mainly on the number of people in the household and how many hot water draw-off points (bathroom, kitchen, etc.) will be used simultaneously.

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

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

Maintenance and servicing in practice

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

Compared to modern condensing boilers, maintaining a cast-iron atmospheric boiler is generally simpler and cheaper - for example, there is no need to worry about a condensate trap 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 reach the efficiency of the most modern condensing solutions, which is a common and fair trade-off between greater initial robustness/simplicity and the highest possible energy efficiency. If the lowest possible gas consumption at all costs is a decisive criterion for you, we are happy to discuss alternatives from the ATTACK condensing range 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-fired cylinder (e.g. from the ATTACK Z-series) must be added, which is ordered and paid for separately.

2. What DHW cylinder is suitable for a boiler with an output of 12-15 kW?
For this output level (up to approx. 18 kW), a smaller cylinder volume from the ATTACK Z-series is generally 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 depends mainly 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 E COMBI range differ from other ranges in the ATTACK COMBI cast-iron lineup (EKO, PLQ, KLQ, E, EZ)?
In short: the E COMBI range is positioned above KLQ COMBI in the ATTACK lineup, with increased operating comfort. We are happy to verify and clarify the exact technical differences compared to KLQ COMBI at this output level upon request.

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 the specific order specification - we recommend stating this requirement when ordering or checking with our sales team in advance.

5. What is the warranty on this boiler?
ATTACK stationary gas boilers are covered by a 30-month warranty 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 conditions are governed by the warranty certificate attached to the specific unit, and the prescribed commissioning conditions must be met (generally by a professional service technician).

6. Can the boiler be connected to an existing natural-draught chimney?
Yes, this is an atmospheric boiler designed for connection to a natural-draught chimney. The suitability of a specific chimney (diameter, height, material) needs to 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 masonry chimney.

7. Can the boiler be connected to a system with multiple heating circuits (e.g. radiators + underfloor heating)?
Yes, combining multiple circuits with different heating water temperatures is common - however, it 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 cylinder, just the body itself?
Yes - this product represents the boiler body itself. The DHW cylinder, 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 the accessories needed, 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 utilise the condensation of water vapour from the flue gases for additional heat gain, so its efficiency does not reach the values of modern condensing boilers. In exchange, it offers a simpler construction, lower sensitivity to the return heating water temperature, 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 online shop. When ordering, we recommend also considering ordering a suitable DHW cylinder from the Z-series and any other necessary accessories (chimney parts, three-way valve, circulation pump, room thermostat) at the same time, so you have a complete solution ready for installation. If you have any doubts about choosing the right combination of boiler + cylinder + accessories, do not hesitate to contact us before ordering - we are happy to advise so that you don't order something you won't ultimately need, or conversely, so that nothing essential is missing.

Warranty and service

ATTACK E 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 ends 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 (generally by a professional service technician authorised for this activity), and a proper service booklet/warranty certificate must be kept. If you have any questions about the warranty, servicing, or choosing suitable accessories (DHW cylinder, circulation pump, chimney parts, controls), do not hesitate to contact us - we are happy to help you choose and order a complete solution tailored to your needs.