ATTACK 30 SLX PROFI - wood gasification boiler

Product detailed description

ATTACK 30 SLX PROFI – wood gasification boiler with 30 kW output

ATTACK 30 SLX PROFI is a modern gasification (pyrolysis) wood boiler with a nominal output of 30 kW, designed for heating family houses, cottages, businesses, and smaller industrial buildings where quality firewood is available. The SLX Profi boiler range combines the proven cast iron and steel construction of the ATTACK brand with controlled two-stage combustion technology, thanks to which it achieves significantly higher efficiency and lower emissions than classic wood boilers with bottom or top burning. The ATTACK SLX Profi range is designed with an emphasis on a larger loading chamber volume and a longer interval between individual fuel loads, which you will appreciate especially when heating larger buildings or if you prefer less frequent refuelling. The larger combustion chamber also allows longer logs to be loaded, simplifying fuel preparation.

The 30 SLX PROFI boiler belongs to energy class A+ and meets the current emission requirements (ecodesign) for solid fuel boilers in the European Union. Due to the gasification principle, the firewood in the boiler does not burn all at once, but gradually – first it undergoes gasification (pyrolysis) in the upper loading chamber under insufficient air supply, and then the resulting combustible gas (a mixture of CO, H2, and hydrocarbons), together with the supplied secondary air, burns completely in the ceramic combustion nozzle and the lower combustion chamber at temperatures exceeding 900 °C. The result is a longer burning time per load of wood, higher efficiency (typically above 88 %), and considerably lower firewood consumption per kilowatt-hour of heat produced compared to a classic boiler.

How wood gasification works and why it is more efficient

A common bottom-burning wood boiler burns fuel all at once with insufficiently controlled air supply, producing large amounts of unburned combustion products (tar, soot, CO) that escape through the chimney and clog the flue. The ATTACK 30 SLX PROFI gasification boiler, on the other hand, divides combustion into two separate phases taking place in two chambers, one above the other. In the upper loading chamber, wood gasifies at high temperature and with insufficient oxygen (it is not directly burned there), while the resulting combustible wood gas is pushed by the combustion air fan through a ceramic (firebrick) nozzle into the lower combustion chamber. There the gas mixes with secondary air and burns completely at a very high temperature. This process brings three main advantages: significantly higher combustion efficiency, minimal tar and soot formation (less cleaning, longer flue and chimney life), and the possibility of smooth output regulation according to current heat demand, since the fan regulates the intensity of combustion instead of manual chimney damper adjustment.

Key features of the ATTACK 30 SLX PROFI boiler

• Wood gasification combustion with two-stage burning and high efficiency above 88 %, energy class A+.
• Large loading chamber with a volume of approximately 120 l allowing a larger amount of wood to be loaded and a longer interval between refuelling.
• Turbulators in the heat exchanger – rotary turbulators increase flue gas turbulence in the heat exchange surface, improve heat transfer to the heating water, and reduce the temperature of flue gases going into the chimney, thereby increasing boiler efficiency.
• Mechanical cleaning of the heat exchanger using an external lever/handle – the operator simply removes ash and soot deposits from the heat exchange surfaces with a few movements of the lever, without having to disassemble the boiler.
• Robust cast iron/steel construction of the boiler body with increased wall thickness resistant to operational wear and thermal stress.
• Ceramic combustion nozzle and combustion chamber lining made of quality firebrick resistant to the high temperatures generated when burning wood gas.
• Combustion air fan with output regulation ensuring the optimal air-to-fuel ratio under varying boiler load.
• Electronic control with display and option of weather-compensated control
• Large service door for convenient access to the combustion chamber, nozzle, and heat exchanger for cleaning and maintenance.
• Safety heat exchanger / option to connect a cooling circuit against boiler overheating (we recommend adding a thermal safety valve in accordance with applicable legislation).
• Ready for conversion to automatic operation using the SL20968 kit for burning pellets (COMBI Pellet), giving the boiler the option of fully automatic refuelling.
• Low emissions and compliance with ecodesign requirements for solid fuel boilers applicable in the EU.

Technical parameters of the ATTACK 30 SLX PROFI

Differences between the Standard and Profi ranges

The 30 SLX PROFI boiler is equipped with the Profi range, which, compared to the basic Standard version, brings an electronic control unit with a clear display, more precise control of combustion air via a motorized damper, and the option to connect a room thermostat or weather-compensated control based on outdoor temperature. Thanks to this, the boiler automatically adjusts its output to the current heat demand of the house, saving wood and extending the interval between refuelling. The Profi version also has thicker insulation of the boiler body, which reduces heat losses into the boiler room and increases operating comfort, especially during year-round operation.

Installation and commissioning

ATTACK SLX gasification boilers operate with a high flue gas temperature in the combustion chamber and are therefore sensitive to so-called low-temperature corrosion, which occurs if water that is too cold returns to the boiler (below approx. 60 °C). During long-term operation with a low return water temperature, acidic combustion products condense on the walls of the heat exchanger, significantly shortening the lifespan of the boiler body. We therefore always recommend installing a mixing (three-way) circuit with a thermostatic head – for example ATTACK / Oventrop or ESBE LTC361 – in the heating system, which maintains the return water temperature to the boiler at a minimum of 60 °C until the boiler reaches operating temperature. This mixing circuit is also a condition for the extended warranty on the boiler body to apply (see the Warranty section below).

Due to the nature of gasification combustion (the boiler works best at an output close to nominal), we strongly recommend adding a buffer tank to the heating system (e.g. the ATTACK AK or AS range with a suitable volume according to the boiler output and the heated building's area). A buffer tank allows the loaded batch of wood to be burned at once at optimal output, and the heat to be "stored" for later use, from which it is gradually drawn into the heating circuit throughout the day. Without a buffer tank, the boiler's output is frequently dampened, which increases tar formation, reduces efficiency, and shortens the lifespan of the boiler and flue. Always have the installation, flue connection, connection to the electrical network, and first commissioning carried out by an authorized heating engineer/service technician in accordance with the project documentation, applicable legislation (in particular technical standards and boiler room regulations), and the manufacturer's installation manual. The first commissioning should be carried out by an authorized ATTACK service technician, which is also one of the conditions for warranty claims.

Fuel and its preparation

The recommended fuel for the ATTACK 30 SLX PROFI boiler is dry firewood (preferably hardwood – beech, oak, hornbeam) with a moisture content of up to 20 %. The moisture content of the wood significantly affects both the boiler's output and its lifespan – wet or freshly cut wood (moisture content 40 % or more) considerably reduces the calorific value, causes incomplete gasification, increased tar and soot formation, and can even lead to the fire going out. Therefore, store wood for at least 1–2 heating seasons under a well-ventilated shelter. The length of the logs should correspond to the dimensions of the boiler's loading chamber (usually up to approx. 50 cm), with a log thickness of approx. 8–15 cm for even and smooth gasification.

Option of conversion to automatic operation – COMBI Pellet

If you are considering more convenient, automatic operation without the need for daily wood refuelling in the future, the ATTACK 30 SLX PROFI boiler can be additionally converted to burn wood pellets using the SL20968 kit with a pellet burner with an output of 30 kW. This conversion kit is intended for ATTACK 20-35 SLX Profi boilers and includes a burner, a pellet hopper, and the necessary control electronics, including connection to the existing boiler control. When ordering the conversion kit, the serial number of the specific boiler to which the kit will be fitted must be provided, so that the service technician can verify compatibility and prepare the correct components. After conversion, the boiler operates as a fully automatic pellet heat source, while the original wood-burning function can, depending on the version, be retained as a backup (combined wood/pellet operation).

Maintenance and cleaning

Regular maintenance is key to maintaining the high efficiency and long lifespan of the ATTACK 30 SLX PROFI boiler. We recommend emptying the ash pan and the space under the grate according to the intensity of heating, usually several times a week. Perform mechanical cleaning of the heat exchanger using the external lever according to the operating manual, ideally once a day during intensive seasonal operation – this will extend the interval between major service cleanings and maintain the boiler's declared efficiency. At least once a year (before the start of the heating season), we recommend having a comprehensive service inspection of the boiler carried out, including checking the door seal, the condition of the ceramic nozzle, the combustion chamber lining, and the functionality of the fan and control system.

Frequently Asked Questions

Is a buffer tank needed for the ATTACK 30 SLX PROFI boiler?
It is not a legal requirement, but it is strongly recommended. A gasification boiler works most efficiently at an output close to the nominal 30 kW, so a buffer tank allows a batch of wood to be burned at once under optimal conditions and the heat to be stored for later use. Without it, output dampening occurs, increasing tar formation and reducing boiler lifespan.

What is the recommended moisture content of the wood?
The recommended moisture content of firewood is up to 20 %, which usually corresponds to wood dried for at least 1–2 years under a shelter. Wetter wood reduces efficiency and increases the risk of clogging the heat exchanger and chimney.

What is low-temperature corrosion and how can it be avoided?
This is damage to the boiler body caused by the condensation of acidic combustion products at too low a return water temperature. It is addressed by installing a mixing (three-way) circuit that maintains the temperature of the water returning to the boiler at a minimum of 60 °C.

Can the 30 SLX PROFI boiler be converted to pellets later?
Yes, using the SL20968 conversion kit designed for 20-35 SLX Profi boilers, which adds a pellet burner and the necessary control electronics for fully automatic operation.

What is the difference between the Standard and Profi ranges?
Compared to the Standard version, the Profi range offers more precise electronic control with a display, the option of weather-compensated control based on outdoor temperature, and usually thicker insulation of the boiler body, providing higher operating comfort and slightly lower fuel consumption during long-term operation.

Who is allowed to carry out the first commissioning of the boiler?
The first commissioning, connection to the flue and electrical network should always be carried out by an authorized heating engineer or an authorized ATTACK service technician, in accordance with the installation manual and applicable legislation. This is also a condition for the warranty to be valid.

What flue diameter does the boiler require?
The ATTACK 30 SLX PROFI boiler is standardly equipped with a 200 mm chimney connection; however, the exact chimney draught and diameter need to be assessed individually according to the height and type of chimney (we recommend consulting a chimney sweep or designer).

Why choose the ATTACK 30 SLX PROFI

ATTACK is a Slovak boiler manufacturer with a long tradition and an extensive service network throughout Slovakia, which is a great advantage when heating with solid fuel – spare parts (ceramic nozzles, seals, fans, control units) are readily available and service is not dependent on imports from abroad. The 30 SLX PROFI boiler is designed to last for decades of operation if the recommended conditions are followed (protection against low-temperature corrosion, quality dry wood, regular maintenance). The combination of cast iron and steel components, ceramic lining of the combustion chamber, and a well-thought-out mechanical heat exchanger cleaning system are among the proven solutions, tested over the years in practice, appreciated by both installation companies and end customers in everyday operation.

When choosing the output of the 30 SLX PROFI boiler, be guided primarily by the heat loss of the heated building calculated according to the applicable standard (STN EN 12831), not just by the approximate floor area of the house. An undersized boiler cannot cover the heat loss on the coldest days, while a significantly oversized boiler operates more often at partial output, which reduces efficiency and increases tar formation in solid fuel boilers. If in doubt about the correct choice of output, we recommend consulting a heating designer or directly an ATTACK sales representative.

Emissions and environmentally friendly operation

Thanks to two-stage controlled combustion and a high operating temperature in the combustion chamber, the ATTACK 30 SLX PROFI boiler achieves significantly lower emissions of particulate matter, CO, and organic compounds compared to classic bottom-burning wood boilers. The boiler meets the requirements of the ecodesign regulation (Directive 2009/125/EC and related implementing regulations) for solid fuel boilers placed on the market in the EU. Lower emissions also mean fewer deposits in the chimney and flue, reducing the risk of soot fires in the chimney and extending the interval needed between chimney sweep cleanings.

Warranty

The manufacturer provides a standard warranty of 36 months from the date of commissioning of the boiler for ATTACK SLX wood gasification boilers, but no more than 42 months from the date of dispatch of the boiler from the factory. When protection against low-temperature corrosion is installed (a mixing circuit maintaining a return temperature of at least 60 °C), an extended 7-year warranty on the boiler body can be claimed. For the warranty to be valid, the first commissioning must be carried out by an authorized ATTACK service technician and the prescribed method of operation must be observed (in particular fuel moisture content and protection against low-temperature corrosion). Exact warranty conditions can be found in the warranty certificate supplied with the boiler.