ATTACK 35 DPX PROFI - wood gasification boiler

Product detailed description

ATTACK 35 DPX PROFI – wood gasification boiler with an output of 35 kW

ATTACK 35 DPX PROFI is a modern gasification (pyrolysis) wood boiler with a rated output of 35 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 combustion. The ATTACK DPX range is a compact gasification boiler designed for common family houses and smaller businesses, where emphasis is placed on a balanced price, ease of use and reliability of the proven cast-iron and steel construction.

The 35 DPX PROFI boiler belongs to energy class A+ and meets the 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 is gasified (pyrolysed) 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 completely burned in the ceramic combustion nozzle and lower combustion chamber at temperatures exceeding 900 °C. The result is a longer burn time per wood load, higher efficiency (typically above 88 %) and considerably lower wood consumption per kilowatt-hour of heat produced compared to a classic boiler.

How wood gasification works and why it is more efficient

A common wood boiler with bottom combustion burns fuel all at once with insufficiently controlled air supply, which produces a large amount of unburned combustion products (tar, soot, CO) that escape through the chimney and clog the flue. The ATTACK 35 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 is gasified at high temperature and insufficient oxygen (it is not directly burned), while the resulting combustible wood gas is forced 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 benefits: significantly higher combustion efficiency, minimal tar and soot formation (less cleaning, longer flue and chimney lifespan) and the possibility of smoothly regulating output according to current heat demand, since the fan regulates the intensity of combustion instead of manual chimney damper adjustment.

Key features of the ATTACK 35 DPX PROFI boiler

• Wood gasification combustion with two-stage combustion and high efficiency above 88 %, energy class A+.
• Large loading chamber with a volume of approximately 100 l allowing a larger amount of wood to be loaded and a longer interval between refuelling.
• Turbulators in the heat exchanger – rotating turbulators increase flue gas turbulence in the heat transfer area, improve heat transfer to the heating water and lower the temperature of flue gases leaving for the chimney, thereby increasing boiler efficiency.
• Mechanical cleaning of the heat exchanger using an external lever/handle – the operator simply moves the lever a few times to knock ash and soot deposits off the heat transfer surfaces 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 at different boiler loads.
• Electronic control with display and the 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 of connecting a cooling circuit against boiler overheating (we recommend adding a thermal safety valve in accordance with valid Slovak legislation).
• Ready for conversion to automatic operation using the DPD30900 kit for burning pellets (COMBI Pellet), which gives the boiler the option of fully automatic feeding.
• Low emissions and compliance with ecodesign requirements for solid fuel boilers valid in the EU.

Technical parameters of ATTACK 35 DPX PROFI

Differences between the Standard and Profi ranges

The 35 DPX PROFI boiler is equipped with the Profi range, which, compared to the basic Standard version, provides an electronic control unit with a clear display, more precise combustion air control via a motorised damper, and the option of connecting a room thermostat or weather-compensated control based on outdoor temperature. This allows the boiler to automatically adjust 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 DPX 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 heating water that is too cold (below approx. 60 °C) returns to the boiler. During long-term operation with a low return water temperature, acidic combustion products condense on the heat exchanger walls, which significantly shortens the lifespan of the boiler body. We therefore 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 heats up to operating temperature. This mixing circuit is also a condition for granting the extended warranty on the boiler body (see the Warranty chapter below).

Given the nature of gasification combustion (the boiler works best at an output close to its rated output), we strongly recommend supplementing the heating system with an accumulation tank (e.g. the ATTACK AK or AS range with a suitable volume according to boiler output and the heated area of the building). An accumulation tank allows a loaded batch of wood to be burned all at once at optimal output, and the heat to be "stored" for later use, being gradually drawn off into the heating circuit throughout the day. Without an accumulation tank, the boiler output is frequently throttled, which increases tar formation, reduces efficiency and shortens the lifespan of both the boiler and the flue. Always have the installation, connection to the flue, connection to the electrical network and initial commissioning carried out by an authorised heating technician/service technician in accordance with the project documentation, valid legislation (in particular relevant standards and boiler room regulations) and the manufacturer's installation manual. Initial commissioning should be carried out by an authorised ATTACK service technician, which is also one of the conditions for warranty claims.

Fuel and its preparation

The recommended fuel for the ATTACK 35 DPX PROFI boiler is dry firewood (preferably hard deciduous wood – beech, oak, hornbeam) with a moisture content of up to 20 %. Wood moisture fundamentally affects both the boiler's output and lifespan – wet or freshly cut wood (moisture content of 40 % or more) significantly reduces heating value, causes incomplete gasification, increased tar and soot formation, and can even lead to the fire going out. Wood should therefore be stored for at least 1–2 heating seasons under a well-ventilated shelter. The length of 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 a more convenient, automatic operation in the future without the need for daily wood refuelling, the ATTACK 35 DPX PROFI boiler can be additionally converted to burning 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 a 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 high efficiency and a long lifespan of the ATTACK 35 DPX PROFI boiler. We recommend emptying the ash pan and the space under the grate according to heating intensity, 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 extends the interval between major service cleanings and maintains 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 an accumulation tank required for the ATTACK 35 DPX PROFI boiler?
It is not a legal requirement, but it is strongly recommended. The gasification boiler works most efficiently at an output close to its rated 35 kW, so an accumulation tank allows a batch of wood to be burned all at once under optimal conditions and the heat to be stored for later use. Without it, output throttling occurs, along with increased tar formation and a shorter boiler lifespan.

What is the recommended wood moisture content?
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 the heat exchanger and chimney becoming clogged.

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 solved by installing a mixing (three-way) circuit that keeps the temperature of the water returning to the boiler at a minimum of 60 °C.

Can the 35 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 to the boiler for fully automatic operation.

What is the difference between the Standard and Profi ranges?
Compared to the Standard version, the Profi range provides 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, resulting in greater operating comfort and slightly lower fuel consumption during long-term operation.

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

What flue diameter does the boiler require?
The ATTACK 35 DPX PROFI boiler is standardly equipped with a chimney connection with a diameter of 180 mm; however, the exact chimney draught and 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 35 DPX PROFI

The ATTACK brand is a Slovak boiler manufacturer with a long-standing tradition and an extensive service network throughout Slovakia, which is a great advantage for solid fuel heating – spare parts (ceramic nozzles, seals, fans, control units) are readily available and service is not dependent on imports from abroad. The 35 DPX PROFI boiler is designed to last for decades of operation provided the recommended conditions are met (protection against low-temperature corrosion, quality dry wood, regular maintenance). The combination of cast-iron and steel components, ceramic combustion chamber lining and well-designed mechanical heat exchanger cleaning 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 35 DPX PROFI boiler, be guided primarily by the heat loss of the heated building calculated according to the valid standard (EN 12831), not just approximately based on the floor area of the house. An undersized boiler cannot cover the heat loss on the coldest days, while a significantly oversized boiler works more often at partial output, which, in the case of solid fuel boilers, reduces efficiency and increases tar formation. If in doubt about the correct output choice, 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 35 DPX PROFI boiler achieves significantly lower emissions of solid pollutants, CO and organic compounds compared to classic wood boilers with bottom combustion. The boiler meets the requirements of the Ecodesign Directive (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 soot fires in the chimney and extends the interval needed between chimney sweep cleanings.

Warranty

The manufacturer provides a standard warranty of 36 months from the date of commissioning for ATTACK DPX wood gasification boilers, but no more than 42 months from the date the boiler was dispatched from the factory. If protection against low-temperature corrosion is installed (a mixing circuit keeping the return temperature at a minimum of 60 °C), an extended 7-year warranty on the boiler body can be applied. For the warranty to be valid, initial commissioning must be carried out by an authorised 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.