ATTACK SLX COMBI PELLET wood and pellet boiler

30 years of development and production

ATTACK SLX COMBI PELLET combination boiler

Logs or automatic pellet firing.

The ATTACK SLX COMBI PELLET combines an SLX wood-gasification boiler with an automatic pellet burner. Its large 200-litre chamber is designed for logs; in pellet mode, the burner automatically feeds and ignites the fuel, then cleans itself.

Wood output

20 kW
25 kW
30 kW
35 kW

Fuel

Logs
Wood pellets

Control system

PROFI

Emission class

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Category: Combination boilers

20–35 kWnominal output on wood

up to 92%efficiency stated on the product page

Easy changeof fuel

Automaticburner operation

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Getting to know the boiler

Choose a topic to learn more about the ATTACK SLX COMBI PELLET boiler, its installation and everyday operation.

Family homes in a snowy winter landscape

For your home

Suitable for different types of home

A solid-fuel boiler with high output and efficiency can suit different types of home. If you meet the criteria, you may also be eligible for support from the Green for Households programme.

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ATTACK SLX COMBI PELLET boiler with a buffer tank and pellet hopper

Installation

Connecting the boiler

A correct flue connection is essential. When choosing a boiler, consider the building, boiler output, chimney and the full heating system.

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Practical advice for your ATTACK wood boiler

Helpful advice

Practical boiler advice

Learn how to light the boiler quickly and efficiently, why tar forms and how to clean it correctly.

How to light the boiler How to clean the boiler Why tar forms

ATTACK biomass boilers eligible for the grant programme

Household support

Green for Households grant programme

Get a modern appliance for your home with a grant of up to €1,500. Request a quote and we will help with the process, including your grant application.

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Flexible heating

Choose logs or pellets

The large SLX chamber is designed for logs. In automatic mode, the Pellet Burner Automatic feeds and ignites pellets, cleans the grate and removes ash into a container. A sliding burner bracket and blanking plate make it possible to change fuels.

ATTACK SLX COMBI PELLET boiler with a buffer tank

ATTACK SLX COMBI PELLET technical features

How the SLX COMBI PELLET works

Explore the main boiler components and compare log-fired and automatic pellet operation.

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Zmena paliva

Logs or automatic pellet firing

When burning logs, a blanking plate closes the burner opening. In pellet mode, the burner handles fuel feeding and ignition.

Burning logs in the loading chamber of the ATTACK SLX COMBI PELLET boiler

Prikladanie dreva

Komora s objemom 200 litrov

The 200-litre chamber accepts logs up to 650 mm long.

Cutaway view of the ATTACK pellet burner during operation

Pellet combustion

The burner automatically ignites and controls combustion

In pellet mode, the automatic burner feeds the fuel, ignites it electrically and controls combustion.

ATTACK pellet burner with its ash tray extended and emptied

Burner maintenance

The burner cleans itself after combustion

After combustion, an automatic cycle removes ash into the container.

Dry jacket on the ATTACK SLX COMBI PELLET boiler

Chamber protection

Dry jacket reduces tar buildup

The thermal barrier limits condensation and tar deposits on the loading-chamber walls.

Flue-gas extraction

Faster flue-gas removal when loading

The extraction channel helps clear flue gases from the chamber before the loading door is opened.

Controls

PROFI control

Designed for everyday heating, the PID controller continuously adjusts fan speed, controls two pumps and supports systems with a buffer tank.

ATTACK SLX COMBI PELLET boiler options

A practical solution for upgrading your boiler room

Technical features presented as practical benefits for design, installation and everyday operation.

Pellet burner

ATTACK Pellet Burner Automatic

Convenient heating with minimal attention: the burner automatically feeds and electrically ignites the pellets. Set the output from 8 to 30 kW in 2 kW increments; add a room thermostat for even more convenient control.

Buffer tank

For higher output, we recommend adding a buffer tank and ATTACK Oventrop mixing assembly to the boiler.

Pellet hopper

A 500 l pellet hopper is also available for the boiler. An external fabric pellet hopper, or big bag, can also be used. The large hopper keeps the boiler burning for longer between refills.

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Flue connection adjustment

Adapt the flue pipe to the layout of the boiler room. A correctly designed connection helps ensure safe and efficient flue-gas removal.

Detailed specifications

Technical data

The Slovak product table lists a nominal pellet output of 40 kW for the 35SLXCP; the operating manual lists 30 kW. The advertised efficiency of up to 92% reflects rounding of the technical table, which lists a maximum of 91.8% for wood. Check the documentation for the exact model when designing the system.

Parameter	Unit	20SLXCP	25SLXCP	30SLXCP	35SLXCP
Nominal output — wood	kW	20	25	30	35
Nominal output — pellets	kW	30	30	30	40
Output range — wood	kW	10–20	12.5–25	15–30	17.5–35
Output range — pellets	kW	8–30	8–30	8–30	8–30
Heat exchanger surface area	m²	2.95	2.95	2.95	2.95
Loading chamber volume	l	200	200	200	200
Rozmer plniaceho otvoru	mm	235 × 445	235 × 445	235 × 445	235 × 445
Required chimney draught	Pa	23	23	23	23
Maximum water operating pressure	kPa	250	250	250	250
Water-side pressure drop (ΔT 10 K)	kPa	1.9	2.1	2.4	2.7
Water-side pressure drop (ΔT 20 K)	kPa	0.8	0.9	1.2	1.6
Boiler weight	kg	610	610	610	610
Flue outlet diameter	mm	150	150	150	150
Boiler height	mm	1 472	1 472	1 472	1 472
Boiler width	mm	703	703	703	703
Boiler depth with burner	mm	1 650	1 650	1 650	1 650
Boiler depth with the upper-door cover	mm	1 350	1 350	1 350	1 350
Flue outlet height — D	mm	985	985	985	985
Fan height — E	mm	751	751	751	751
Chamber depth	mm	690	690	690	690
Electrical component protection rating	IP	20	20	20	20
Electrical input — wood	W	42	42	42	42
Electrical input during pellet ignition	W	600	600	600	600
Electrical input — pellets	W	96	160	160	190
Standby electrical input	W	<5	<5	<5	<5
Boiler efficiency — wood	%	91.8	91.6	90.3	90.3
Boiler efficiency — pellets	%	90.8	90.5	90.2	90.6
Boiler class — wood	—	5	5	5	5
Boiler class — pellets	—	5	5	5	5
Flue-gas temperature at nominal output — wood	°C	165	170	185	170
Flue-gas temperature at nominal output — pellets	°C	145	152	168	148
Flue-gas temperature at minimum output — pellets	°C	109	116	129	110
Flue-gas mass flow at nominal output	kg/s	0.018	0.02	0.022	0.025
Flue-gas mass flow at minimum output	kg/s	0.005	0.007	0.009	0.012
Maximum noise level	dB	65	65	65	65
Specified fuel — wood	—	Dry wood, calorific value 15–17 MJ/kg, moisture content 12–20%, diameter 80–150 mm	Dry wood, calorific value 15–17 MJ/kg, moisture content 12–20%, diameter 80–150 mm	Dry wood, calorific value 15–17 MJ/kg, moisture content 12–20%, diameter 80–150 mm	Dry wood, calorific value 15–17 MJ/kg, moisture content 12–20%, diameter 80–150 mm
Specified fuel — pellets	—	Wood pellets, Ø 6 mm, 35 mm long, moisture content up to 12%; DIN 51 731–HP 5, DIN Plus or EN 14961-2–A1	Wood pellets, Ø 6 mm, 35 mm long, moisture content up to 12%; DIN 51 731–HP 5, DIN Plus or EN 14961-2–A1	Wood pellets, Ø 6 mm, 35 mm long, moisture content up to 12%; DIN 51 731–HP 5, DIN Plus or EN 14961-2–A1	Wood pellets, Ø 6 mm, 35 mm long, moisture content up to 12%; DIN 51 731–HP 5, DIN Plus or EN 14961-2–A1
Average fuel consumption — wood	kg/h	6.5	7.8	9.1	10.4
Average fuel consumption — pellets	kg/h	2.4–6.9	2.4–6.9	2.4–6.9	2.4–6.9
Wood consumption per season	—	1 kW = 1 m³	1 kW = 1 m³	1 kW = 1 m³	1 kW = 1 m³
Maximum log length	mm	650	650	650	650
Burn time at nominal output	h	8	7.2	6.5	5.8
Objem vody v kotle	l	117	117	117	117
Minimum buffer tank volume	l	1 500	2 000	2 200	2 500
Supply voltage	V/Hz	230/50	230/50	230/50	230/50
Minimum return-water temperature	°C	65	65	65	65
Rozsah nastavenia teploty vykurovacej vody	°C	65–90	65–90	65–90	65–90
Controller contact load capacity	V/A	230/2	230/2	230/2	230/2
Heating system connection	″	G 6/4″	G 6/4″	G 6/4″	G 6/4″