DEFRO DWS 17 kW solid fuel boiler hard coal boiler

The DEFRO DWS 17 kW is a manually fed solid fuel boiler for hard coal with bottom-down combustion. With an efficiency of up to 89.9%, it meets the requirements of Class 5 according to PN-EN 303-5 and is ideally suited for single-family homes. In combination with a buffer storage tank, it can be operated as a primary heating system or as a supplementary boiler.

Highlights/Advantages

⭐ High efficiency up to 89.9% – efficient use of fuel
⭐ Emission class 5 according to PN-EN 303-5 – meets strict environmental requirements
⭐ Robust construction with ceramic combustion chamber – durable and easy to maintain.
⭐ Suitable for open and closed systems according to DIN EN 12828
⭐ Ideally combined with a buffer storage tank – optimized, low-emission combustion.

Detailed description

Area of ​​application & Target audience

The DEFRO DWS 17 kW is a central heating boiler for hot water heating systems with a maximum flow temperature of 90 °C. It is suitable for single-family homes and smaller buildings with medium heat demand.

The product is suitable for use in both open and closed heating systems according to DIN EN 12828. A buffer storage tank is mandatory in closed systems.

Everyday benefits

The boiler operates on the principle of bottom combustion. The special ceramic material in the combustion chamber promotes clean afterburning of the exhaust gases. This reduces emissions and improves efficiency.

The large loading door allows for convenient manual feeding. The heat exchanger and combustion chamber are easily accessible via inspection openings, facilitating cleaning and maintenance.

Technology & equipment

The DEFRO DWS 17 kW is a manually fed solid fuel boiler for hard coal (type 31.2 – nut coal). Alternatively, lignite briquettes or logs can be used, however, emissions measurements are only taken with hard coal.

The boiler features:

• Cast iron grate

• Ceramic combustion chamber lining

• Fire draft regulator (mechanical)

• Analog temperature display

• Cleaning openings and turbulators

• Connection fitting for thermal relief valve

An integrated safety heat exchanger is not included. An external double thermal relief valve must be installed.

Efficiency & Environment

The measured efficiency is 89.6–89.9% at nominal output. This means the boiler meets the requirements of class 5 according to PN-EN 303-5.

Emission values ​​at 10% O₂:

• CO: 20.4 mg/m³

• OGC: 4.0 mg/m³

• Dust: 14.5 mg/m³

The boiler meets the requirements of the 1st Federal Immission Control Ordinance (1. BImSchV) when properly installed, adjusted and operated with suitable fuel.

compatibility & System integration

A buffer storage tank is essential for optimized operation. This stores excess heat energy and ensures low-emission full-load operation.

The hydraulic connection must be equipped with:

• Safety valve (max. 3 bar)

• Return temperature boost (minimum return temperature 65 °C)

• Thermal safety device

• Expansion vessel according to EN 12828

take place.

Technical data

Dimensions (17 kW):

• Width (A): 520 mm

• Depth (B): 594 mm

• Height (D): 1315 mm

Scope of delivery

• DEFRO DWS 17 kW boiler (encased and insulated)

• Cleaning tool

• Firebricks for combustion chamber

• Turbulators for heat exchangers

• Fire draft regulator

• Assembly and operating instructions

Accessories/Recommendation

For safe and efficient operation, we recommend:

• Buffer storage tank (suitable models under gemashop.de)

• Double thermal safety device (e.g. Caleffi)

• Boiler safety group

• Return flow boost valve

• Suitable flue pipes and draft regulators

Suitable components can be found in the heating technology accessories section at:
https://gemashop.de

Assembly & Safety instructions

Installation must be carried out exclusively by an approved specialist company.

Prior to commissioning, the approval of the responsible chimney sweep is required. The boiler may only be installed on a non-combustible surface. Minimum distances to combustible building components must be observed.

A thermal relief valve is mandatory. Operation without a buffer tank in closed systems is not permitted.

FAQ

1. Which fuels are permitted?
The main fuel is hard coal (type 31.2 – nut coal 20–25 mm). Lignite briquettes and firewood are technically possible, but not approved for emission measurements.

2. Does the boiler meet the requirements of the first...BImSchV?
Yes, with correct installation, adjustment and suitable fuel, it meets the requirements of class 5 according to PN-EN 303-5.

3. Is a buffer storage tank necessary?
Yes. The buffer storage tank is mandatory for proper operation and a warranty requirement in closed systems.

4. Is a return flow boost required?
Yes. The return temperature must not fall below 65 °C.

5. Is a safety heat exchanger integrated?
No. An external thermal safety device must be installed.

6. What is the efficiency?
The efficiency is 89.6–89.9% at rated power.

Conclusion

The DEFRO DWS 17 kW is a robust and efficient solid fuel boiler for use with hard coal. Combined with a buffer storage tank, it offers a reliable and standards-compliant heating solution for residential buildings. Order now and modernize your heating system with reliability.