ATMOS D 20 PX

Product detailed description

The ATMOS D 20 PX is designed for installation in compact spaces such as small boiler rooms or utility areas in residential and light commercial buildings. It integrates all essential components—fuel tank, auger conveyor and burner—into a single unit, reducing space requirements and simplifying installation. The boiler is ideal for hydronic heating systems requiring a variable thermal output between 4.5 and 20 kW. It is commonly used in conjunction with buffer tanks and heat distribution systems such as underfloor heating or radiators. The design ensures consistent heat delivery with minimal manual intervention.

Due to its compact size and self-contained design, the D 20 PX is well suited for retrofitting into existing buildings with limited space. The boiler operates using high-quality 6–8 mm pellets with a calorific value of 16–19 MJ/kg, ensuring stable and clean combustion. The system is fully automated, including ignition and fuel dosing, making it suitable for unattended operation. The ceramic-lined combustion chamber enhances burn efficiency while the tube heat exchanger allows for routine cleaning without disassembly. The absence of a cooling circuit eliminates the risk of overheating during power outages, given the low fuel volume in the burner.

Technical parameters

The boiler’s thermal output range of 4.5–20 kW allows for flexible sizing based on building heat demand. A minimum 500 L buffer tank is required to ensure stable operation and reduce cycling. The 175 L fuel tank minimises the frequency of refills, while the 76 L water content supports thermal inertia. The 16 Pa chimney draft requirement ensures proper flue gas removal, and the 250 kPa maximum working pressure defines the hydraulic system’s pressure limits. These parameters are essential for determining system compatibility and correct installation.

Installation and connection

Installation should begin with verifying the available space and ensuring the room has adequate ventilation and access for maintenance. The boiler requires a minimum 500 L buffer tank connected via standard threaded fittings. Flue connections must meet the 16 Pa draft specification, typically achieved with a correctly sized chimney or flue pipe. Electrical connections include a dedicated 6.3 A fuse and a control panel with operational and safety thermostats. Ensure the fuel tank is positioned to allow the auger conveyor to operate freely without obstruction.

Common installation errors include undersized buffer tanks, incorrect chimney sizing and improper electrical wiring. Verify the boiler’s grounding and insulation, particularly in damp environments. The ceramic-lined combustion chamber and tube heat exchanger require careful alignment during installation to prevent mechanical stress. After installation, test the boiler’s ignition sequence and monitor the pressure gauge to confirm the system is operating within the specified 250 kPa limit.

Compatibility and accessories

The D 20 PX is compatible with standard hydronic heating systems, including radiators, underfloor heating and domestic hot water circuits. It requires a buffer tank of at least 500 L and is typically paired with a circulation pump and expansion vessel. The boiler comes equipped with two KTF20-5m sensors for temperature monitoring. Optional accessories include a pneumatic pellet transport system and a burner with pneumatic cleaning, both of which can enhance performance in larger installations. Related products include other models from the KOMPAKT series and auxiliary controls for advanced automation.

Technical background for designers

The D 20 PX operates on the principle of automated pellet combustion with electronic ignition and fuel dosing. Pellets are fed from the 175 L storage tank via an auger conveyor to the A25 pellet burner located in the front of the boiler. The lower combustion chamber is lined with ceramic blocks to optimise flame retention and improve combustion efficiency. The rear-mounted tube heat exchanger is equipped with segmented baffles to enhance heat transfer and facilitate coarse cleaning without dismantling components.

Constructed from 3–5 mm thick steel plates, the boiler body is insulated with mineral wool and sintered foam to reduce heat loss. The front panel includes a main switch, burner control, operational thermostat, safety thermostat and a 6.3 A fuse for electrical protection. The absence of a cooling circuit ensures safe operation during power failures, as the low fuel load in the burner prevents overheating. The system integrates easily into existing heating networks, provided the buffer tank and flue system meet the specified requirements.

Service and operation

Regular maintenance includes cleaning the combustion chamber and removing ash from the front access panel. The tube heat exchanger allows for operational cleaning without removing the tubes, reducing downtime. Check the chimney draft periodically to ensure it remains at 16 Pa. Inspect the auger conveyor for blockages and verify the fuel quality to maintain combustion efficiency. The control panel should be checked for error codes, and the safety thermostat tested annually to ensure proper function.

No specific service intervals are provided in the brief, but routine inspections and cleaning are recommended to maintain performance. Always follow the manufacturer’s guidelines when handling electrical components and flue systems. The ceramic-lined chamber and heat exchanger are durable but require careful handling to avoid damage during maintenance.

Frequently asked questions

Can the D 20 PX be connected to a domestic hot water system?
Yes, the boiler can be integrated into a hydronic system with a domestic hot water circuit, provided the buffer tank and circulation pump are correctly sized.

What type of pellets are recommended for the D 20 PX?
High-quality pellets with a diameter of 6–8 mm and a calorific value of 16–19 MJ/kg are specified for optimal combustion performance.

Is a buffer tank required for the D 20 PX?
A minimum 500 L buffer tank is required to stabilise the system and reduce cycling, ensuring efficient operation.

Can the boiler be upgraded with a pneumatic cleaning system?
Yes, the D 20 PX can be equipped with a burner featuring pneumatic cleaning, enhancing maintenance efficiency in larger installations.