Product Overview & Application
The Defro Firewood Plus 15 kW is a natural draft boiler for split logs and serves as a heat generator for hot water heating systems with a buffer tank. It is of interest to operators looking for a manually fed wood boiler with classic split log combustion, electronic primary air control, and a solid boiler construction.
The boiler is designed for operation in closed heating systems and is fueled with untreated split logs. Its power class makes it suitable for smaller to medium-sized heating systems, though the specific design must always match the heating load, buffer tank, and existing flue system.
Technology & Equipment
The Firewood Plus 15 operates as a natural draft boiler with manual feeding and an electronic draft regulator. Primary air supply is controlled via the air flap, while secondary air is directed to combustion through side inlets. The construction uses convection channels and turbulators to transfer heat from the flue gases to the heating water.
Equipment includes an analog boiler thermometer, a cast iron combustion grate, a steel insert in the combustion chamber, turbulators, a safety heat exchanger, and cleaning tools. The combustion and heat exchanger areas are accessible through the doors for cleaning and maintenance.
Everyday Benefits
In daily operation, the electronic control supports the primary air supply, making operation easier compared to purely mechanically controlled split log boilers. The analog thermometer allows for simple monitoring of the boiler temperature directly on the unit.
The side viewing windows help monitor combustion without needing to open the firebox door. Cleaning accessibility via the boiler doors and the included cleaning tools support regular maintenance of the heat exchanger and combustion chamber.
System Integration & Compatibility
The Defro Firewood Plus 15 kW is designed for integration into closed hot water heating systems. For safe and stable operation, combining it with a buffer tank is a key part of system planning.
Hydraulic integration must be planned with appropriate return temperature boosting, safety fittings, a thermal drain safety device, and a correctly sized flue system. Before installation, coordination with a specialist company and a chimney sweep should be carried out to ensure the boiler, buffer tank, chimney, and heating system are technically compatible.
Technical Specifications at a Glance
The following technical data refers to the Defro Firewood Plus 15 kW variant.
| Rated Output | 15 kW |
| Fuel | Untreated split logs, residual moisture 12–20% |
| Combustion Technology | Natural draft |
| Efficiency | 92.4% |
| Energy Efficiency Class | A+ |
| Max. Flow Temperature | 90 °C |
| Max. Operating Pressure | 3.0 bar |
| Boiler Class | 5 according to EN 303-5:2012 |
| Draft Requirement | 18 Pa |
| Flue Gas Temperature | 142 °C |
| Flue Pipe Connection | Ø 159 mm |
| Safety Heat Exchanger | Included |
| Buffer Tank | Required |
| Height | 1350 mm |
| Width | 555 mm |
| Depth | 1035 mm |
| Weight | approx. 348 kg |
| Voltage | 230 V |
| Frequency | 50 Hz |
| Fuse Protection | 1.25 A |
| Power Consumption | max. 5 W |
| Phases | 1N |
Installation
The boiler must be installed in accordance with applicable regulations, manufacturer documentation, and the requirements of the heating system. The boiler must be placed on a suitable, load-bearing surface and requires sufficient clearances for operation, cleaning, and maintenance.
Hydraulically, the Firewood Plus 15 kW must be planned with a buffer tank, return temperature boosting, safety valve, expansion vessel, and thermal drain safety device. Connection to the chimney, heating system, and power supply should be carried out by qualified specialist companies.
Notes
Only untreated split logs with suitable residual moisture should be used for operation. Damp, treated, coated, or unsuitable fuel material can negatively affect operation, emissions, and the service life of the boiler.
Before commissioning, maintenance, and cleaning, the included manufacturer documentation must be observed. System planning must ensure that boiler output, buffer tank, return temperature, chimney draft, and heat demand are professionally matched.
Scope of Delivery
- Defro Firewood Plus 15 kW natural draft boiler
- Boiler operating manual
- Electronic draft regulator
- Analog boiler thermometer
- Steel insert for the combustion chamber
- Primary air flap
- Cleaning tool set
- Cast iron combustion grate
- Turbulator set
- Safety heat exchanger
