Product Overview & Application
The Defro Firewood Plus 24 kW is a hand-fed natural draft boiler for split logs, designed for use as a central heat source in hot water heating systems. With a nominal output of 24 kW, the boiler is suitable for heating systems where a log boiler with a buffer tank is professionally integrated into a closed heating system.
The boiler is designed for operation with natural split logs and combines a robust boiler construction with controlled combustion air supply. The specific output selection should always be based on the actual heat demand of the building.
Technology & Equipment
The Firewood Plus 24 operates as a natural draft boiler with a hand-fed firebox, cast iron grate, steel insert in the combustion chamber, and multi-pass flue gas routing. Heat transfer occurs via a steel heat exchanger with vertical and horizontal convection channels.
Primary air is supplied through the air flap in the ash door and regulated by the electronic draft controller. Secondary air enters the combustion zone through side air inlets. The equipment includes, among other things, an analog boiler thermometer, turbulators, a safety heat exchanger, and cleaning tools.
Everyday Benefits
The separate arrangement of the loading door, ignition door, and ash door facilitates access to the combustion chamber, ash pan, and heat exchanger area. For cleaning and maintenance, the relevant boiler areas are accessible so that routine care tasks can be performed systematically.
Inspection windows on the boiler sides allow flame observation without unnecessarily opening the door. The thermal insulation of the boiler body reduces heat losses from the boiler surface and supports quiet system operation in the boiler room.
System Integration & Compatibility
The natural draft boiler is intended for closed hot water heating systems and must be operated with a suitable buffer tank. For safe and stable system operation, return temperature boosting, chimney connection, safety devices, and hydraulic integration must be coordinated with the overall system.
Planning and installation should be carried out by a qualified specialist company. Before installation, the flue gas system must be coordinated with the responsible chimney sweep, particularly regarding chimney draft, flue pipe routing, and cross-section.
Technical Specifications at a Glance
The following values summarize the key technical data of the Defro Firewood Plus 24 kW.
| Nominal Output | 24 kW |
| Fuel | Split logs, preferably birch, residual moisture 12–20% |
| Combustion Technology | Natural draft |
| Efficiency at Nominal Output | 92.3% |
| Energy Efficiency Class | A+ |
| Max. Flow Temperature | 90 °C |
| Max. Operating Pressure | 3.0 bar |
| Log Length | max. 400 mm |
| Boiler Class | Class 5 per EN 303-5:2012 |
| Draft Requirement | 20 Pa |
| Flue Gas Temperature at Nominal Output | 154 °C |
| Flue Pipe Connection | Ø 178 mm |
| Safety Heat Exchanger | Yes |
| Buffer Tank Recommended | Yes, min. 55 liters per kW |
| Connection Size | Flow and return female thread 1 ½ inch |
| Height | 1460 mm |
| Width | 655 mm |
| Depth | 1035 mm |
| Weight | approx. 429 kg |
| Voltage | 230 V |
| Frequency | 50 Hz |
| Power Consumption | max. 5 W |
Installation
The boiler must be installed in accordance with applicable regulations and manufacturer specifications. The boiler must be placed on a suitable, load-bearing, and non-combustible base and positioned to allow easy operation, cleaning, and maintenance.
For operation, a professionally dimensioned chimney, suitable return temperature boosting, and a buffer tank are required. The electrical connection of the draft controller must be carried out by an electrician or appropriately qualified personnel.
Notes
The boiler may only be operated with the fuels specified in the manufacturer's documentation. For operation with split logs, attention must be paid to suitable wood quality, appropriate residual moisture, and correct log length.
The output specification serves for technical classification and does not replace a heat load calculation. Maintenance, cleaning, water quality, return temperature, and chimney draft affect the operational safety and service life of the entire heating system.
Scope of Delivery
- Defro Firewood Plus 24 kW natural draft boiler
- Boiler operating manual
- Electronic draft controller
- Analog boiler thermometer
- Steel insert for the combustion chamber
- Primary air flap
- Cleaning tools
- Cast iron grate
- Turbulators
- Safety heat exchanger
