DEFRO DWS 17 kW solid fuel boiler hard coal boiler

2025-04-16T12:25:46+02:00

Vendor: Defro
Type: Solid fuel boiler
Price: 1800.00

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

feature | Value
Manufacturer | DEFRO
Model | DWS 17
Product type | Manually fed solid fuel boiler
Nominal heat output | 17 kW
Energy efficiency class | B
Efficiency at rated power | 89.6–89.9%
Exhaust gas mass flow | 10.2 g/s
CO₂ emissions | 11%
Exhaust gas temperature | 149 °C
Permissible operating pressure | 2.5 bar
Maximum operating temperature | 85 °C
Minimum operating temperature | 75 °C
Minimum return temperature | 60 °C
boiler water content | 92 liters
Weight | 411 kg
Exhaust connection | Ø 159 mm
Flow/Return | 1½" internal thread
Required chimney negative pressure | 21 Pa
Burning time per filling | 2–4 h
fuel | Bituminous coal (Type 31.2 – Nut coal 20–25 mm)
Standards | PN-EN 303-5:2012, DIN EN 12828
CE marking | Yes

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.