ATTACK 15 KLQ 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 withstands a less gentle operating regime (frequent switching, fluctuating 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, facilities, workshops, small businesses or multi-generational homes with higher heat consumption.

Another advantage of the cast-iron body is easy maintenance and serviceability - a cast-iron exchanger usually consists 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 service 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 KLQ COMBI range and is rated for a nominal heat output of 12-15 kW. It is a stationary gas boiler in the COMBI version - in the context of this cast-iron range, this means that the boiler itself does not have its own (built-in) domestic hot water (DHW) preparation. To heat domestic hot water, the boiler therefore needs to be supplemented with an external indirectly heated 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 greater comfort of hot water draw-off at several points simultaneously is required, since storage tank heaters can cover even temporarily higher DHW consumption better than instantaneous heating.

The ATTACK KLQ COMBI range represents a higher equipment standard within the cast-iron range. Boilers in this range are designed for customers who expect more comfortable, quieter and more stable operation from a stationary gas boiler than with the basic EKO or PLQ ranges. In practice, this means higher-quality workmanship, more sophisticated combustion control and generally a somewhat higher degree of automation of operation. KLQ COMBI is a suitable compromise between price and usable value for more demanding households as well as smaller facilities.

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

When choosing a stationary gas boiler, customers often ask why they should choose a cast-iron exchanger when cheaper steel or lighter aluminium solutions are also available on the market. The answer is primarily related to the long-term durability of the material. Cast iron has higher thermal inertia than thin-walled steel, which in practice means calmer, less "nervous" combustion and less 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 sectional (segmented) construction already mentioned. A cast-iron exchanger is not made of a single piece but of several sections stacked on top of each other, connected by sealing gaskets. If one section were to be 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 usually 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 its higher weight (see the approximate value in the technical parameters table below) and a somewhat slower thermal response when starting from a cold state - however, for a stationary boiler intended for long-term, predominantly continuous operation (not frequent switching on/off as with a cottage used only 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 KLQ 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 intended for wall mounting like common 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 long service life and easy serviceability of the equipment matter
• Larger buildings and multi-generational homes with higher heat consumption, where the robustness of the cast-iron body is appreciated
• Smaller facilities, workshops, guesthouses or cottages with year-round or near 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 piping 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 core, or a boiler with its own fast DHW preparation without the need for a separate storage tank, a cast-iron stationary COMBI boiler is probably not the most suitable 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 12-15 kW, natural gas fuel (LPG version on request/according to specific order specification)
• COMBI version = boiler without its own DHW preparation, designed to work with an external indirectly heated storage tank (e.g. ATTACK Z-series)
• Sectional (segmented) cast-iron exchanger - allows replacement of a single section instead of the entire body if damaged
• Connection to a naturally draught chimney (atmospheric combustion)
• Robust construction suitable also for larger buildings and facilities with higher heating output requirements
• Higher standard of workmanship and control compared to the basic EKO/PLQ ranges
• The delivery includes the boiler body itself, including the burner and basic control - the 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 given as an approximate estimate based on the output category and the common construction of sectional cast-iron boilers of this class - we recommend verifying the exact value for a specific unit in the manufacturer's current technical datasheet or directly with us before ordering, especially if you are planning exact construction preparation of the room or niche for the boiler.

How to connect: boiler + external DHW storage tank

Since this is a COMBI version without its own domestic hot water preparation, this boiler needs to be connected together with a separate (external) indirectly heated DHW storage tank. In the ATTACK range, the so-called Z-series of storage tanks is intended for this purpose (e.g. Z100PLUS, Z125PLUS, Z100NTR, Z125NTRA, Z160NTRA, Z125OKC, Z160OKC, Z200OKC and other versions including OKCV wall-mounted horizontal variants) - we sell these storage tanks 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 storage tank volume is usually sufficient from the ATTACK Z-series range, 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 volume of 100 vs. 125 l 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 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 hot water. Switching between the heating circuit and heating the storage tank is usually ensured 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 (piping route, placement of pumps, safety and mixing fittings) 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 authorised heating/gas professional who will also take into account locally applicable standards and regulations for connecting a gas appliance.

When ordering the boiler and storage tank, we will gladly 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 hot water draw-off points used simultaneously - do not hesitate to contact us before purchasing if you are not sure about the right choice.

Maintenance and service in practice

As with any gas appliance, a regular service inspection of the ATTACK stationary cast-iron boiler (usually once a year, carried out by an authorised service technician) 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 flue gas path, and verifying correct combustion settings.

Compared to modern condensing boilers, maintaining an atmospheric cast-iron boiler is usually simpler and cheaper - for example, there is no need to take care of 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 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 the decisive criterion for you, we will gladly discuss alternatives from ATTACK's condensing range with you.

Frequently asked questions

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

2. Which DHW storage tank is suitable for a boiler with an output of 12-15 kW?
For this output level (up to approx. 18 kW), a smaller storage tank volume is usually sufficient from the ATTACK Z-series range, 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 volume of 100 vs. 125 l 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. What distinguishes the KLQ COMBI range from other ranges in ATTACK's cast-iron COMBI offering (EKO, PLQ, KLQ, E, EZ)?
In brief: it represents a higher equipment standard within the cast-iron range - higher-quality workmanship and more sophisticated control compared to the basic EKO and PLQ ranges.

4. What type of fuel is the boiler designed for, and can it be converted to another fuel?
In the 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 contacting our sales team in advance.

5. What warranty applies to 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 conditions are governed by the warranty certificate enclosed with the specific unit, and the prescribed commissioning conditions must be followed (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 for connection to a naturally draught chimney. The suitability of a specific chimney (diameter, height, material) needs to be assessed individually, ideally during an on-site inspection 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 will gladly prepare a complete list of the accessories needed for 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 return, it offers a simpler construction, lower sensitivity to the return heating water temperature and usually 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 will gladly 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 storage tank from the Z-series and any other accessories (chimney parts, three-way valve, circulation pump, room thermostat) at the same time, so that you have a complete solution ready for installation. If you are unsure about the right combination of boiler + storage tank + accessories, do not hesitate to contact us before ordering - we will gladly advise you so that you don't order something you won't end up needing, or conversely, so that nothing essential is missing.

Warranty and service

ATTACK KLQ COMBI stationary cast-iron gas boilers are covered by a standard warranty of 30 months from commissioning of the boiler, 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 qualified service technician authorised for this activity), and a proper service booklet/warranty certificate must be kept. If you have any questions about the warranty, service or choosing suitable accessories (DHW storage tank, circulation pump, chimney parts, controls), do not hesitate to contact us - we will gladly help you choose and order a complete tailored solution.