ATTACK 25 DPX PROFI - wood gasification boiler

Product detailed description

ATTACK 25 DPX PROFI – wood gasification boiler with 25 kW output

ATTACK 25 DPX PROFI is a modern gasification (pyrolysis) wood boiler with a nominal output of 25 kW, designed for heating family houses, cottages, businesses and smaller industrial buildings where quality firewood is available. The DPX 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 DPX range is a compact gasification boiler intended for standard family houses and smaller operations where emphasis is placed on a balanced price, simple operation and reliability of proven cast-iron and steel construction.

The 25 DPX PROFI boiler belongs to energy class A+ and meets current emission requirements (ecodesign) placed on solid fuel boilers in the European Union. Due to the gasification principle, the firewood in the boiler is not burned all at once, but gradually – first, it gasifies (pyrolyzes) in the upper loading chamber under insufficient air supply, and the resulting combustible gas (a mixture of CO, H2 and hydrocarbons), together with supplied secondary air, is then perfectly burned in the ceramic combustion nozzle and 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 wood consumption per unit of heat produced compared to a classic boiler.

How wood gasification works and why it is more efficient

A common wood boiler with bottom burning burns fuel all at once with insufficiently controlled air supply, producing a large amount of unburned combustion products (tar, soot, CO), which escape through the chimney and clog the flue. The ATTACK 25 DPX PROFI gasification boiler, on the other hand, splits combustion into two separate phases taking place in two chambers, one above the other. In the upper loading chamber, wood gasifies at high temperature under insufficient oxygen (it does not burn directly), and the resulting combustible wood gas is pushed by the combustion air fan through a ceramic (fireclay) 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 benefits: significantly higher combustion efficiency, minimal formation of tar and soot (less cleaning, longer lifespan of the flue and chimney) and the possibility of smooth output regulation according to the current heat demand, since the fan regulates the intensity of combustion instead of manual chimney damping.

Key features of the ATTACK 25 DPX 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 80 l allowing a larger amount of wood to be loaded and a longer interval between refuelling.
• Turbulators in the heat exchanger – rotary turbulators increase the turbulence of flue gases in the heat exchange area, improve heat transfer to the heating water and reduce the temperature of the flue gases leaving into the chimney, thereby increasing the boiler's efficiency.
• Mechanical cleaning of the heat exchanger using an external lever/handle – the operator simply knocks the ash and soot deposits off the heat exchange surfaces with a few movements of the lever without having to dismantle 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 high-quality fireclay resistant to high temperatures generated during wood gas combustion.
• Combustion air fan with output regulation ensuring an optimal ratio of air and fuel under different boiler loads.
• Electronic control with display and possibility of weather-compensated control
• Large service door for convenient access to the combustion chamber, nozzle and heat exchanger during 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 current Slovak legislation).
• Ready for conversion to automatic operation using the DPD30900 kit for pellet combustion (COMBI Pellet), giving the boiler fully automatic fuel feeding capability.
• Low emissions and compliance with ecodesign requirements for solid fuel boilers valid in the EU.

Technical parameters of ATTACK 25 DPX PROFI

Differences between the Standard and Profi series

The 25 DPX PROFI boiler is equipped with the Profi series, which, compared to the basic Standard version, adds an electronic control unit with a clear display, more precise control of combustion air using a motorized damper, and the option to connect a room thermostat or weather-compensated control based on outdoor temperature. As a result, 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 on the boiler body, which reduces heat loss into the boiler room and increases operating comfort, especially during year-round operation.

Installation and commissioning

ATTACK DPX gasification boilers operate with high flue gas temperature in the combustion chamber and are therefore sensitive to so-called low-temperature corrosion, which occurs if the heating water returning to the boiler is too cold (lower than approx. 60 °C). During long-term operation with a low return water temperature, acidic combustion products condense on the walls of the heat exchanger, which significantly shortens the lifespan of the boiler body. Therefore, we always recommend installing a mixing (three-way) circuit with a thermostatic head in the heating system – for example ATTACK / Oventrop or ESBE LTC361 – which keeps the temperature of the return water to the boiler at a minimum of 60 °C until the boiler warms up to its operating temperature. This mixing circuit is also a condition for recognition of the extended warranty on the boiler body (see the Warranty chapter below).

Due to the nature of gasification combustion (the boiler works best at output close to nominal), we strongly recommend supplementing the heating system with a buffer tank (e.g. the ATTACK AK or AS series with a suitable volume according to the boiler output and the heated 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, which is gradually drawn from during the day into the heating circuit. Without a buffer tank, the boiler's output is frequently dampened, which increases tar formation, reduces efficiency and shortens the lifespan of both the boiler and the flue. Installation, connection to the flue, connection to the electrical network and initial commissioning should always be carried out by an authorized heating engineer/service technician in accordance with the project documentation, current legislation (especially STN standards and regulations on boiler rooms) and the manufacturer's installation manual. Initial 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 25 DPX PROFI boiler is dry firewood (preferably hard deciduous wood – beech, oak, hornbeam) with a moisture content of up to 20 %. The moisture content of the wood fundamentally affects both the output and lifespan of the boiler – wet or freshly cut wood (moisture content of 40 % and more) significantly reduces the calorific value, causes incomplete gasification, increased formation of tar and soot, and can even cause the fire to go out. Therefore, wood should be stored 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), the thickness of the logs approx. 8–15 cm for even and smooth gasification.

Option of conversion to automatic operation – COMBI Pellet

If you are considering a more comfortable, automatic operation in the future without the need for daily refuelling of wood, the ATTACK 25 DPX PROFI boiler can be additionally converted to burn wood pellets using the DPD30900 kit with a 30 kW pellet burner. This conversion kit is intended for ATTACK 25-35 DPX Standard/Profi boilers and includes a burner, pellet hopper and the necessary control electronics including connection to the boiler's existing controls. When ordering a conversion kit, it is necessary to report the serial number of the specific boiler to which the kit will be fitted, so that the service technician can verify compatibility and prepare the correct components. After conversion, the boiler works 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 high efficiency and a long lifespan of the ATTACK 25 DPX PROFI boiler. We recommend emptying the ash tray and the space under the grate according to the intensity of heating, usually several times a week. Mechanical cleaning of the heat exchanger using the external lever should be performed according to the operating manual, ideally once a day during intensive seasonal operation – this will extend the interval between major service cleaning 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 controls.

Frequently Asked Questions

Is a buffer tank necessary for the ATTACK 25 DPX PROFI boiler?
It is not a legal requirement, but it is strongly recommended. A gasification boiler works most efficiently at output close to the nominal 25 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, along with increased tar formation and a shorter lifespan of the boiler.

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 condensation of acidic combustion products at too low a return water temperature. It is solved by installing a mixing (three-way) circuit, which keeps the temperature of the water returning to the boiler at a minimum of 60 °C.

Can the 25 DPX PROFI boiler later be converted to pellets?
Yes, using the DPD30900 conversion kit designed for 25-35 DPX Standard/Profi boilers, which adds a pellet burner and the necessary control electronics for fully automatic operation to the boiler.

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

Who is allowed to carry out initial commissioning of the boiler?
Initial commissioning, connection to the flue and the 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 current legislation. This is also a condition for the validity of the warranty.

What flue diameter does the boiler require?
The ATTACK 25 DPX PROFI boiler is standardly equipped with a chimney connection with a diameter of 150 mm; however, the exact chimney draft and chimney diameter must be assessed individually according to the height and type of chimney (we recommend consulting a chimney sweep or designer).

Why choose the ATTACK 25 DPX 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 commonly available and service is not dependent on imports from abroad. The 25 DPX PROFI boiler is designed to last decades of operation when the recommended conditions are met (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 thoughtful mechanical cleaning of the heat exchanger is 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 25 DPX PROFI boiler, be guided primarily by the heat loss of the heated building calculated according to the current standard (STN EN 12831), not just approximately according to the area of the house. An undersized boiler cannot cover the heat loss on the coldest days, while, on the other hand, a significantly oversized boiler works more often at partial output, which, in the case of solid fuel boilers, reduces efficiency and increases tar formation. In case of doubts 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 25 DPX PROFI boiler achieves significantly lower emissions of solid pollutants, CO and organic compounds compared to classic wood boilers with bottom burning. The boiler meets the requirements of the ecodesign regulation (Directive 2009/125/EC and related implementing regulations) placed on solid fuel boilers placed on the market in the EU. Lower emissions also mean fewer deposits in the chimney and flue, which reduces the risk of a soot fire in the chimney and extends the interval needed between cleanings by a chimney sweep.

Warranty

For ATTACK DPX wood gasification boilers, the manufacturer provides a standard warranty of 36 months from the date of commissioning the boiler, but no more than 42 months from the date of dispatch of the boiler from the factory. If protection against low-temperature corrosion is installed (a mixing circuit maintaining a return temperature of at least 60 °C), it is possible to claim an extended 7-year warranty on the boiler body. For the warranty to be valid, it is necessary for the initial commissioning to be carried out by an authorized ATTACK service technician and for the prescribed method of operation to be followed (especially fuel moisture and protection against low-temperature corrosion). You can find the exact warranty terms in the warranty card supplied with the boiler.