Wood burning boiler BURNiT NWB PRIME 70, 70kW

Steel boiler with intelligent electronic controller and electric fan for forced air feed. Solid fuel boilers NWB PRIME range in nominal output from 20 to 110 kW to satisfy the heating demands of medium to large sized spaces. They are engineered for burning solid fuel - wood, wood briquettes class B and coal, and provide the option for fitting pellet, oil or gas-fired burners.

Manufacture

The boiler body is manufactured from high quality steel with 5mm thickness for the combustion chamber and 3mm thickness for the water mantle. The combustion chamber has a large heat exchanging surface and low chamber impedance. Large firebox door ensures easy loading even of large chunks of wood.

Controller ST-81

ST–81 temperature regulator is intended for controlling central heating boilers. It controls the water circulation pump, domestic hot water pump and the fan. Four optional modes of the pumps operation: house heating, boiler priority, parallel pumps, summer mode. The controller's casing is designed to be mounted to the boiler installation. Its functions are based on data from sensors. The electronic control unit regulates the burning process with the blower, based on the fuel used and the chimney draught, allowing for a wide range of operation.

Effectiveness

To increase the heat exchange, the combustion chamber's surface is ribbed and designed for a three-pass flue gas flow. The mantle completely envelops the firebox for maximized usage of the heat. The boiler's body is insulated from the external conditions by 50mm thick high temperature resisting wool.

Safety devices

For a safe and reliable operation of the boiler, a number of safety devices are installed

- Removable metallic ash grate protects the heat exchanging pipes and the chamber base from the flame

- Pressure relief valve 3 bar incl.in the delivery set

- Safety heat evacuator: a tap-water filled line passes through the uppermost part of the boiler body. In case of overheating it is triggered open by a thermostatic valve (not included) to evacuate the heat off the boiler.

Fuel

The central heating boiler can operate with natural untreated wood, but also with coal and compressed solid fuel such as briquettes. Maximum length of the wood logs is between 330mm and 500mm depending on the model. Fuel moisture should be 20% or lower.

In order to use the maximum caloricity of the fuel, the wood logs should be dried for a prolonged period of time. High moisture levels reduces caloricity and the output power of the boiler.

Versatility

This series of boilers is manufactured for burning solid fuel, with the option of adaptation to a different kind of fuel. This is possible by mounting a pellet, gas or an oil burner on the lower door opening. A flange is also needed to mount the burner (optional).

Schematic of the main features of a NWB PRIME wood boiler

 Legend:

1. Control unit
2. Casing
3. High efficiency thermal insulation
4. Safety heat evacuator
5. Three-pass flue gas flow
6. Mantle
7. Combustion chamber
8. Metal ash grate
9. Ash- and- soot container
10. Burner flange (optional)
11. Flue
12. Air feed fan
13. Air intake flap

This appliance complies with EN 303-5.